Complete MS3Pro Documentation

Complete MS3Pro Documentation
CONTENTS
CONTENTS
Contents
1 Introduction
1.1 Overview . . . . . . . . . . . . . . . . . .
1.1.1 Warning labels . . . . . . . . . . .
1.1.2 Technical support . . . . . . . . .
1.1.3 Copyrights . . . . . . . . . . . . .
1.2 MS3-Pro components . . . . . . . . . . .
1.2.1 MS3-Pro Engine Control Unit . . .
1.2.2 Wiring harness . . . . . . . . . . .
1.2.3 Tuning cables . . . . . . . . . . . .
1.3 MS3-Pro accessories . . . . . . . . . . .
1.3.1 Sensors . . . . . . . . . . . . . . .
1.3.2 QuadSpark . . . . . . . . . . . . .
1.3.3 Ignition coils . . . . . . . . . . . .
1.3.4 CAN-EGT thermocouple interface
1.3.5 MicroSquirt . . . . . . . . . . . . .
1.3.6 Part numbers . . . . . . . . . . . .
1.4 Tools . . . . . . . . . . . . . . . . . . . . .
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2 Installing software
2.1 TunerStudio . . . . . . . . . . . .
2.1.1 Start screen . . . . . . . .
2.1.2 Creating a project . . . .
2.1.3 TunerStudio main screen
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15
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3 MS3-Pro hardware
3.1 Overview . . . . . . . . . . . . . . . . . . .
3.2 Inputs . . . . . . . . . . . . . . . . . . . . .
3.2.1 Engine speed . . . . . . . . . . . . .
3.2.2 Temperature inputs . . . . . . . . . .
3.2.3 Throttle position . . . . . . . . . . .
3.2.4 O2 sensor input . . . . . . . . . . .
3.2.5 MAP sensor input . . . . . . . . . .
3.2.6 General purpose analog inputs . . .
3.2.7 Knock input . . . . . . . . . . . . . .
3.2.8 Digital I/O channels . . . . . . . . .
3.3 Outputs . . . . . . . . . . . . . . . . . . . .
3.3.1 Injector outputs . . . . . . . . . . . .
3.3.2 Ignition outputs . . . . . . . . . . . .
3.3.3 High current outputs . . . . . . . . .
3.3.4 PWM medium current outputs . . . .
3.3.5 Tach output . . . . . . . . . . . . . .
3.3.6 Stepper motor control output . . . .
3.4 Communications lines . . . . . . . . . . . .
3.4.1 RS232 . . . . . . . . . . . . . . . . .
3.4.2 USB . . . . . . . . . . . . . . . . . .
3.4.3 CANbus . . . . . . . . . . . . . . . .
3.5 Maintenance inside the case . . . . . . . .
3.5.1 Changing the fuses . . . . . . . . .
3.5.2 Replacing the SD card . . . . . . . .
3.5.3 Changing the real time clock battery
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DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
Page 2
CONTENTS
CONTENTS
3.5.4 Improving the waterproofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4 Wiring
4.1 ECU pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2 Wiring diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3 Engine position sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.0.1 Variable reluctor sensors . . . . . . . . . . . . . . . . . . . .
4.3.0.2 Hall effect and optical sensors . . . . . . . . . . . . . . . . .
4.3.0.3 Points triggering and points replacement devices . . . . . . .
4.3.0.4 Fuel only with an MSD box or similar . . . . . . . . . . . . .
4.4 Other sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.4.1 Temperature sensors . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.4.2 MAP sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.4.3 Throttle position sensor . . . . . . . . . . . . . . . . . . . . . . . . . .
4.4.4 Mass air flow sensors . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.4.4.1 Ford 5.0 Mustang 4 pin oval connector MAF . . . . . . . . .
4.4.4.2 Ford 5 pin rectangular connector MAF . . . . . . . . . . . . .
4.4.4.3 Nissan / Infiniti Q45 MAF . . . . . . . . . . . . . . . . . . . .
4.4.5 Oxygen sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.4.6 Knock sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.4.7 Speed and gear sensors . . . . . . . . . . . . . . . . . . . . . . . . .
4.4.8 Generic on/off switches . . . . . . . . . . . . . . . . . . . . . . . . . .
4.4.9 Other sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5 Fuel injectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6 Ignition outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6.0.1 QuadSpark ignition module . . . . . . . . . . . . . . . . . . .
4.6.0.2 IGN-1A coil with built in ignition module . . . . . . . . . . . .
4.6.0.3 LS series coils . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6.0.4 VW pencil coils . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6.0.5 MSD and other single channel capacitive discharge ignitions
4.6.0.6 Common firing orders . . . . . . . . . . . . . . . . . . . . . .
4.7 IAC valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7.1 Stepper IAC valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7.2 PWM IAC valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7.3 On/off IAC valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7.4 Thermal IAC valves . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7.5 DC servo IAC valves (currently not supported) . . . . . . . . . . . . .
4.8 Fuel pump relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.9 Tach output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.10 High current outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.11 PWM medium current outputs . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.12 Grounding notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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5 Setting up a basic configuration
5.1 Connecting the MS3-Pro to your laptop
5.2 Basic engine constants . . . . . . . . .
5.3 Ignition settings . . . . . . . . . . . . . .
5.3.1 Specific ignitions: Basic Trigger .
5.3.1.1 Input phasing . . . . . .
5.3.1.2 Ford TFI distributors . .
5.3.1.3 GM HEI . . . . . . . . .
5.3.2 Specific ignitions: Trigger Return
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DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
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Page 3
CONTENTS
CONTENTS
5.3.3 Specific (non) ignition: Fuel only . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.4 Specific ignition: Toothed wheel . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.4.1 Terminology notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.4.2 Wheel naming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.4.3 Specific settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.4.4 Existing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.4.5 Retrofit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.4.6 Missing tooth crank wheel . . . . . . . . . . . . . . . . . . . . . . . .
A note about VR sensors and missing tooth wheels . . . . . . . . . . . .
5.3.4.7 Missing tooth cam wheel . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.4.8 Missing tooth crank wheel and single tooth cam wheel . . . . . . . . .
5.3.4.9 Missing tooth crank wheel and polled (50/50 or half moon) cam wheel
5.3.4.10 Nippon Denso CAS . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.4.11 Non-missing tooth cam wheel with single-tooth cam . . . . . . . . . .
5.3.4.12 Non-missing tooth cam wheel with two opposite teeth on the cam . .
5.3.4.13 Non-missing tooth cam wheel with one cam tooth per cylinder . . . .
5.3.4.14 Non-missing tooth crank wheel with one cam tooth . . . . . . . . . . .
5.3.4.15 Other wheel arrangements . . . . . . . . . . . . . . . . . . . . . . . .
5.3.5 Specific ignitions: EDIS and EDIS Multispark . . . . . . . . . . . . . . . . . . .
5.3.5.1 Checking the timing . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.5.2 Cam sensor and EDIS . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.6 Specific ignitions: 420A/Neon . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.7 Specific ignitions: 36-2+2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.8 Specific ignitions: 36-2-2-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.9 Specific ignitions: Subaru 6/7 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.10 Specific ignitions: Miata 99-05 . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.11 Specific ignitions: 6G72 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.12 Specific ignitions: IAW Weber . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.13 Specific ignitions: CAS 4/1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.14 Specific ignitions: 4G63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.15 Specific ignitions: Twin trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.16 Specific ignitions: Chrysler 2.2 / 2.5 . . . . . . . . . . . . . . . . . . . . . . . .
5.3.17 Specific ignitions: Renix 44-2-2 . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.18 Specific ignitions: Suzuki Swift . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.19 Specific ignitions: Suzuki Vitara 2.0 . . . . . . . . . . . . . . . . . . . . . . . .
5.3.20 Specific ignitions: Daihatsu 3cyl . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.21 Specific ignitions: Daihatsu 4cyl . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.22 Specific ignitions: VTR1000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.23 Specific ignitions: Rover #1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.24 Specific ignitions: Rover #2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.25 Specific ignitions: Rover #3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.26 Specific ignitions: GM 7X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.27 Specific ignitions: QR25DE . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.28 Specific ignitions: Honda RC51 . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.29 Specific ignitions: Fiat 1.8 16V . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.30 Specific ignitions: Optispark . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.31 Specific ignitions: Nissan SR20 . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.32 Specific ignitions: Nissan RB25 . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.33 Specific ignitions: LS1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.34 Specific ignitions: YZF1000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.35 Specific ignitions: Honda Acura (V6) . . . . . . . . . . . . . . . . . . . . . . . .
5.3.36 Specific ignitions: VQ35DE . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
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CONTENTS
5.3.37 Specific ignitions: Jeep 2000 . . . .
5.3.38 Specific ignitions: Jeep 2002 . . . .
5.3.39 Specific ignitions: Zetec VTC . . . .
5.3.40 Specific ignitions: Flywheel tri-tach .
5.3.41 Specific ignitions: 2JZ VVTi . . . . .
5.3.42 Specific ignitions: Honda TSX / D17
5.3.43 Specific ignitions: Viper V10 . . . .
5.3.44 Specific ignition: Honda K24A2 . . .
5.3.45 Specific ignition: HD32-2 . . . . . .
5.3.46 Specific ignition: Miata 36-2 . . . . .
5.4 Idle valves . . . . . . . . . . . . . . . . . . .
5.4.1 On / Off settings . . . . . . . . . . .
5.4.2 Stepper valve settings . . . . . . . .
5.4.3 PWM idle valve settings . . . . . . .
5.5 Sensor calibration . . . . . . . . . . . . . .
CONTENTS
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6 Tuning the MS3-Pro
6.1 Getting started . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.1 Using output test mode . . . . . . . . . . . . . . . .
6.1.1.1 Injector test mode . . . . . . . . . . . . . .
6.1.1.2 Coil test mode . . . . . . . . . . . . . . . .
6.1.1.3 Idle valve testing . . . . . . . . . . . . . . .
Testing a stepper IAC valve . . . . . . . . . .
Testing a PWM IAC valve . . . . . . . . . . .
6.1.2 Checking RPM . . . . . . . . . . . . . . . . . . . . .
6.1.3 Setting cranking timing . . . . . . . . . . . . . . . . .
6.1.4 Starting the engine . . . . . . . . . . . . . . . . . . .
6.1.5 Setting running timing . . . . . . . . . . . . . . . . .
6.2 The basics of 3D tuning tables and load types . . . . . . . .
6.3 Tuning fuel . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.1 Dead time . . . . . . . . . . . . . . . . . . . . . . . .
6.3.1.1 Injector settings . . . . . . . . . . . . . . .
6.3.2 Small pulse widths . . . . . . . . . . . . . . . . . . .
6.3.3 AFR table . . . . . . . . . . . . . . . . . . . . . . . .
6.3.4 VE table . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.5 Basic acceleration enrichment (AE) tuning . . . . . .
6.3.5.1 Main accel enrich settings menu . . . . . .
6.3.5.2 Accelerator pump AE . . . . . . . . . . . .
6.3.5.3 Time Based AE . . . . . . . . . . . . . . .
6.3.5.4 Getting it dialed in . . . . . . . . . . . . . .
MAP based or TPS based AE? . . . . . . . .
Setting the TPSdot/MAPdot Threshold Levels
Tuning the tables . . . . . . . . . . . . . . . .
6.3.6 Startup / warmup fueling . . . . . . . . . . . . . . . .
6.3.6.1 Cranking / Startup settings . . . . . . . . .
6.3.6.2 Priming pulse . . . . . . . . . . . . . . . .
6.3.6.3 Afterstart (ASE) percentage . . . . . . . .
6.3.6.4 Afterstart (ASE) taper . . . . . . . . . . . .
6.3.6.5 Warmup enrichment . . . . . . . . . . . . .
6.3.6.6 Putting it all together . . . . . . . . . . . . .
6.4 Tuning spark . . . . . . . . . . . . . . . . . . . . . . . . . .
6.5 Getting a good idle . . . . . . . . . . . . . . . . . . . . . . .
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DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
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Page 5
CONTENTS
CONTENTS
6.5.0.7
6.5.0.8
6.5.0.9
Correct Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Correct Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Correct Airflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
7 Additional items: Beyond basic fuel and ignition control
7.1 Basic / Load Sections . . . . . . . . . . . . . . . . . . . . . .
7.1.1 General Settings . . . . . . . . . . . . . . . . . . . . .
7.1.1.1 Barometric settings . . . . . . . . . . . . . .
7.1.1.2 MAP sensor settings . . . . . . . . . . . . .
7.1.1.3 General Sensor Settings . . . . . . . . . . .
7.1.1.4 Load Parameters . . . . . . . . . . . . . . .
7.1.2 Rev Limiter . . . . . . . . . . . . . . . . . . . . . . . .
7.1.2.1 Hard rev limit . . . . . . . . . . . . . . . . . .
7.1.2.2 Coolant temp limiter . . . . . . . . . . . . . .
7.1.2.3 Spark retard . . . . . . . . . . . . . . . . . .
7.1.2.4 Spark cut . . . . . . . . . . . . . . . . . . . .
7.1.2.5 Fuel cut . . . . . . . . . . . . . . . . . . . . .
7.1.3 Shift light . . . . . . . . . . . . . . . . . . . . . . . . .
7.1.4 Tacho Output . . . . . . . . . . . . . . . . . . . . . . .
7.1.5 Fan control . . . . . . . . . . . . . . . . . . . . . . . .
7.1.6 Torque converter lockup . . . . . . . . . . . . . . . . .
7.1.7 Barometric correction . . . . . . . . . . . . . . . . . .
7.1.8 MAP sample settings . . . . . . . . . . . . . . . . . .
7.1.8.1 Event Average . . . . . . . . . . . . . . . . .
7.1.8.2 Timed Minimum . . . . . . . . . . . . . . . .
7.1.9 ITB load settings . . . . . . . . . . . . . . . . . . . . .
7.1.9.1 ITB load VE table . . . . . . . . . . . . . . .
7.1.9.2 ITB load TPS switch point curve . . . . . . .
7.1.9.3 ITB Load at TPS Switchpoint Curve . . . . .
7.1.9.4 Putting it all Together - Calculating ITB Load
7.1.9.5 ITB Load Calculation in Speed-Density Mode
7.1.9.6 ITB Load Calculation in Alpha-N Mode . . .
7.1.9.7 Tuning For Idle Air Control . . . . . . . . . .
7.1.10 MAF options . . . . . . . . . . . . . . . . . . . . . . .
7.1.10.1 More about frequency based MAFs . . . . .
7.1.11 MAF flow curve . . . . . . . . . . . . . . . . . . . . . .
7.1.11.1 MAF Load . . . . . . . . . . . . . . . . . . .
7.1.11.2 Tuning . . . . . . . . . . . . . . . . . . . . .
7.1.11.3 Using VE1 as a trim table . . . . . . . . . . .
7.1.12 MAF correction table (old) . . . . . . . . . . . . . . . .
7.1.13 MAF / MAT correction table . . . . . . . . . . . . . . .
7.1.14 Realtime Display . . . . . . . . . . . . . . . . . . . . .
7.1.15 Feature List Shiwing I/O Pins . . . . . . . . . . . . . .
7.1.16 I/O Pins Showing Useage . . . . . . . . . . . . . . . .
7.1.17 Expansion I/O Pins List / Usage . . . . . . . . . . . .
7.1.18 Gauge and setting limits . . . . . . . . . . . . . . . . .
7.2 Fuel Settings . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.2.1 Injector timing table . . . . . . . . . . . . . . . . . . .
7.2.2 Secondary injector timing table . . . . . . . . . . . . .
7.2.3 Staged injection . . . . . . . . . . . . . . . . . . . . .
7.2.3.1 Tuning Staged Injection . . . . . . . . . . . .
7.2.3.2 Tuning Table-based Staged Injection . . . . .
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CONTENTS
7.2.3.3 Tuning All other Staged Injection Modes
7.2.4 Fuel sensor settings (Flex) . . . . . . . . . . . .
7.2.5 AFR / EGO control . . . . . . . . . . . . . . . . .
7.2.5.1 Basic EGO settings . . . . . . . . . . .
7.2.5.2 EGO ports . . . . . . . . . . . . . . . .
7.2.5.3 AFR/EGO Sensor Mapping . . . . . . .
7.2.5.4 Tuning . . . . . . . . . . . . . . . . . .
Simple algorithm with narrowband sensor
Simple Algorithm with Wideband Sensor .
PID Algorithm with Narrowband Sensor .
PID Algorithm with Wideband Sensor . .
7.2.6 Narrowband EGO targets . . . . . . . . . . . . .
7.2.7 AFR safety system . . . . . . . . . . . . . . . . .
7.2.8 Cylinder trim tables . . . . . . . . . . . . . . . . .
7.2.9 Sequenced Batch Fire . . . . . . . . . . . . . . .
7.3 Ignition Settings . . . . . . . . . . . . . . . . . . . . . .
7.3.1 Dwell battery correction . . . . . . . . . . . . . .
7.3.2 Dwell vs RPM . . . . . . . . . . . . . . . . . . . .
7.3.3 Dwell Table . . . . . . . . . . . . . . . . . . . . .
7.3.4 Cold advance . . . . . . . . . . . . . . . . . . . .
7.3.5 MAT based timing retard . . . . . . . . . . . . . .
7.3.6 Noise filtering . . . . . . . . . . . . . . . . . . . .
7.3.6.1 Examples . . . . . . . . . . . . . . . . .
7.3.7 Knock sensor settings . . . . . . . . . . . . . . .
7.3.7.1 Knock sensor settings . . . . . . . . . .
7.3.7.2 Detection . . . . . . . . . . . . . . . . .
7.3.7.3 Retarding . . . . . . . . . . . . . . . . .
7.3.7.4 Recovery . . . . . . . . . . . . . . . . .
7.3.7.5 Knock input threshold . . . . . . . . . .
7.3.8 Knock sensor parameters . . . . . . . . . . . . .
7.3.9 Knock window settings . . . . . . . . . . . . . . .
7.3.10 Knock coolant scaling . . . . . . . . . . . . . . .
7.3.11 Rotary settings . . . . . . . . . . . . . . . . . . .
7.3.11.1 FC mode . . . . . . . . . . . . . . . . .
7.3.11.2 FD mode . . . . . . . . . . . . . . . . .
7.3.11.3 RX8 mode . . . . . . . . . . . . . . . .
7.3.11.4 3 rotor . . . . . . . . . . . . . . . . . . .
7.3.11.5 4 rotor . . . . . . . . . . . . . . . . . . .
7.3.12 Rotary split table . . . . . . . . . . . . . . . . . .
7.3.13 Cylinder trim tables . . . . . . . . . . . . . . . . .
7.4 Startup / Idle . . . . . . . . . . . . . . . . . . . . . . . .
7.4.1 Cranking / startup settings . . . . . . . . . . . . .
7.4.2 Cranking Taper Curve . . . . . . . . . . . . . . .
7.4.3 Priming Pulse 2 through Warmup Enrichment 2 .
7.4.4 Idle control . . . . . . . . . . . . . . . . . . . . .
7.4.4.1 On/Off Valve . . . . . . . . . . . . . . .
7.4.4.2 Stepper valve settings . . . . . . . . . .
7.4.4.3 PWM idle valve settings . . . . . . . . .
7.4.5 Idle Cranking Duty / Steps . . . . . . . . . . . . .
7.4.6 Idle Warmup Duty / Steps . . . . . . . . . . . . .
7.4.7 Closed loop idle settings . . . . . . . . . . . . . .
7.4.7.1 Tuning closed loop idle . . . . . . . . .
CONTENTS
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CONTENTS
7.4.8
7.4.9
7.4.10
7.4.11
7.4.12
Closed loop idle target curve . . . . . . . . . . . . .
Closed loop idle initial values . . . . . . . . . . . . .
PWM Idle voltage compensation . . . . . . . . . . .
Air conditioning idle up . . . . . . . . . . . . . . . . .
Idle advance settings . . . . . . . . . . . . . . . . .
7.4.12.1 Idle advance tuning . . . . . . . . . . . . .
7.4.12.2 Tuning Idle Advance Engagement Settings
7.4.12.3 Tuning Idle Advance Timing . . . . . . . .
7.4.13 Idle RPM timing correction curve . . . . . . . . . . .
7.4.14 Idle VE settings . . . . . . . . . . . . . . . . . . . . .
7.5 Accel Enrich . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.1 TPS WOT curve . . . . . . . . . . . . . . . . . . . .
7.5.2 Enhanced acceleration enrichment . . . . . . . . . .
7.5.2.1 Adheres to Walls Coefficient . . . . . . . .
7.5.2.2 EAE Sucked-from-walls coefficient . . . . .
7.5.2.3 EAE Adhere-to-walls RPM correction . . .
7.5.2.4 EAE Sucked-from-walls RPM correction . .
7.5.2.5 EAE Adhere-to-walls CLT correction . . . .
7.5.2.6 EAE Sucked-from-walls CLT correction . .
7.5.2.7 Tuning EAE . . . . . . . . . . . . . . . . .
7.5.3 X-Tau acceleration enrichment . . . . . . . . . . . .
7.5.3.1 Puddling Factors . . . . . . . . . . . . . . .
7.5.3.2 Time factors . . . . . . . . . . . . . . . . .
7.5.3.3 X (Puddling) Temp Correction Factors . . .
7.5.3.4 Tau (Time) temp corrections . . . . . . . .
7.5.3.5 MAP . . . . . . . . . . . . . . . . . . . . .
7.5.3.6 X-Tau tuning tips . . . . . . . . . . . . . . .
7.6 Boost / VVT . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.6.1 Boost control settings . . . . . . . . . . . . . . . . .
7.6.1.1 Boost control common settings . . . . . . .
7.6.1.2 Closed loop specific settings . . . . . . . .
7.6.1.3 Overboost Protection . . . . . . . . . . . .
7.6.1.4 Other Boost Control Settings . . . . . . . .
7.6.2 Boost control duty table . . . . . . . . . . . . . . . .
7.6.3 Boost control target table . . . . . . . . . . . . . . .
7.6.4 Boost control initial duty table . . . . . . . . . . . . .
7.6.5 Boost delay . . . . . . . . . . . . . . . . . . . . . . .
7.6.6 Boost control vs speed . . . . . . . . . . . . . . . .
7.6.7 Boost 2 control settings . . . . . . . . . . . . . . . .
7.6.8 Turbo anti-lag (ALS) . . . . . . . . . . . . . . . . . .
7.6.9 Turbo anti-lag tables . . . . . . . . . . . . . . . . . .
7.6.10 ALS roving idle fuel cut % . . . . . . . . . . . . . . .
7.6.11 VVT settings . . . . . . . . . . . . . . . . . . . . . .
7.6.12 VVT intake and exhaust tables . . . . . . . . . . . .
7.6.13 VVT on/off table . . . . . . . . . . . . . . . . . . . .
7.7 Table Choices . . . . . . . . . . . . . . . . . . . . . . . . . .
7.7.0.1 Example scenarios . . . . . . . . . . . . .
7.7.0.2 Fuel blending and switching types . . . . .
7.7.0.3 Fuel settings . . . . . . . . . . . . . . . . .
Single algorithm, single table . . . . . . . . .
Single algorithm with table switching . . . . .
Single algorithm with table blending . . . . .
CONTENTS
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CONTENTS
Dual table . . . . . . . . . . . . . . . . . . . . .
7.7.0.4 Spark / ignition blending and switching types
Single table . . . . . . . . . . . . . . . . . . . .
Single algorithm with table switching . . . . . .
Single algorithm with table blending . . . . . .
Combined tables - secondary additive table . .
Secondary algorithm blended table . . . . . . .
7.7.0.5 AFR blending and switching types . . . . . .
7.7.0.6 Boost table switching . . . . . . . . . . . . .
7.7.1 Table Switch / Dual Fuel . . . . . . . . . . . . . . . . .
7.7.2 Temperature Adjustment . . . . . . . . . . . . . . . . .
7.7.3 Pressure Adjustment . . . . . . . . . . . . . . . . . . .
7.7.4 Alt Injector Dead-time 2 . . . . . . . . . . . . . . . . .
7.7.5 Alt Injector small pulsewidths 2 . . . . . . . . . . . . .
7.7.6 Blend curve menus . . . . . . . . . . . . . . . . . . . .
7.8 Advanced Engine . . . . . . . . . . . . . . . . . . . . . . . . .
7.8.1 Speed and gear sensors . . . . . . . . . . . . . . . .
7.8.1.1 Analogue linear input . . . . . . . . . . . . .
7.8.1.2 Digital pulse input to MS3-Pro . . . . . . . .
Wheel mounted . . . . . . . . . . . . . . . . . .
Driveline mounted . . . . . . . . . . . . . . . .
7.8.1.3 Speed value from a remote CAN device . . .
7.8.1.4 Pulse data from a remote CAN device . . . .
7.8.1.5 Menu settings . . . . . . . . . . . . . . . . .
7.8.1.6 VSS dot smoothing . . . . . . . . . . . . . .
7.8.1.7 VSS output . . . . . . . . . . . . . . . . . . .
7.8.2 Shaft Speed Sensors . . . . . . . . . . . . . . . . . .
7.8.3 EGT / Thermocouple settings . . . . . . . . . . . . . .
7.8.4 Generic sensor inputs . . . . . . . . . . . . . . . . . .
7.8.4.1 Source . . . . . . . . . . . . . . . . . . . . .
7.8.4.2 Field Name . . . . . . . . . . . . . . . . . . .
7.8.4.3 Transformation . . . . . . . . . . . . . . . .
7.8.4.4 0V, 5V value . . . . . . . . . . . . . . . . . .
7.8.4.5 Lag . . . . . . . . . . . . . . . . . . . . . . .
7.8.4.6 CLT/MAT temp units . . . . . . . . . . . . . .
7.8.4.7 Allow Input Sharing . . . . . . . . . . . . . .
7.8.5 Accelerometer parameters . . . . . . . . . . . . . . .
7.8.5.1 Collecting calibration data . . . . . . . . . .
7.8.6 Traction control settings . . . . . . . . . . . . . . . . .
7.8.6.1 Traction control settings . . . . . . . . . . . .
7.8.7 Traction control - perfect run VSS . . . . . . . . . . . .
7.8.8 Traction control - perfect run RPM . . . . . . . . . . .
7.8.9 Traction control - External % slip input . . . . . . . . .
7.8.10 Traction control reactions . . . . . . . . . . . . . . . .
7.8.11 Launch / 2 step / 3 step / T-Brake . . . . . . . . . . . .
7.8.11.1 Basic launch control / flat shift settings . . .
7.8.11.2 Variable launch settings . . . . . . . . . . . .
7.8.11.3 Transbrake and throttle stop . . . . . . . . .
7.8.11.4 3 step / burnout limiter . . . . . . . . . . . . .
7.8.12 Timed retard after launch . . . . . . . . . . . . . . . .
7.8.13 Sequential shift cut . . . . . . . . . . . . . . . . . . . .
7.8.14 Nitrous system . . . . . . . . . . . . . . . . . . . . . .
CONTENTS
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Page 9
CONTENTS
7.8.14.1 Wet flow nitrous . . . . . . . . . .
7.8.14.2 Dry nitrous . . . . . . . . . . . . .
7.8.14.3 On/Off . . . . . . . . . . . . . . .
7.8.14.4 Progressive control . . . . . . . .
7.8.14.5 Multistage and progressive nitrous
7.8.14.6 Tuning considerations . . . . . . .
7.8.14.7 Nitrous settings . . . . . . . . . .
7.8.15 Nitrous - time based progressive . . . . . .
7.8.16 Nitrous - time based progressive . . . . . .
7.8.17 Water injection . . . . . . . . . . . . . . . .
7.8.18 High Power Time Enrichment . . . . . . . .
7.8.19 Oil Pressure . . . . . . . . . . . . . . . . .
7.8.20 Programmable on/off outputs . . . . . . . .
7.8.20.1 Output port pane . . . . . . . . . .
7.8.20.2 Port settings pane . . . . . . . . .
7.8.20.3 Conditions . . . . . . . . . . . . .
Output channel . . . . . . . . . . . .
>=< . . . . . . . . . . . . . . . . .
Threshold . . . . . . . . . . . . . . .
Hysteresis . . . . . . . . . . . . . . .
Additional condition . . . . . . . . .
7.8.21 Generic PWM outputs . . . . . . . . . . . .
7.8.22 Generic Closed Loop outputs . . . . . . . .
7.9 3D Tuning Maps . . . . . . . . . . . . . . . . . . .
7.10 CAN bus / Testmodes . . . . . . . . . . . . . . . .
7.10.1 CAN parameters . . . . . . . . . . . . . . .
7.10.1.1 Base data . . . . . . . . . . . . .
7.10.1.2 PWM polling . . . . . . . . . . . .
7.10.1.3 Digital I/O . . . . . . . . . . . . . .
7.10.1.4 PWM outputs . . . . . . . . . . . .
7.10.1.5 Analog (ADC) inputs over CAN . .
7.10.2 CAN broadcasting . . . . . . . . . . . . . .
7.10.3 CAN VSS, gear, EGO . . . . . . . . . . . .
7.10.4 Real time clock . . . . . . . . . . . . . . . .
7.10.5 Check Engine Light . . . . . . . . . . . . .
7.10.5.1 Check Engine codes . . . . . . .
7.10.6 Limp Mode . . . . . . . . . . . . . . . . . .
7.10.7 Fallback MAP table . . . . . . . . . . . . . .
7.10.8 Output test mode - Inj / spark . . . . . . . .
7.10.8.1 Fuel Pump . . . . . . . . . . . . .
7.10.8.2 Coils . . . . . . . . . . . . . . . .
7.10.8.3 Injectors . . . . . . . . . . . . . .
7.10.9 Output test mode - I/O . . . . . . . . . . . .
7.10.10Output test mode - idle valve . . . . . . . .
7.10.11Injector Sequence Testing . . . . . . . . . .
7.10.12Inj / Spk Disabling Test Mode . . . . . . . .
7.10.13Special options . . . . . . . . . . . . . . . .
CONTENTS
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DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
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Page 10
1 INTRODUCTION
8 Troubleshooting and Data Logging
8.1 Resets . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.2 Capturing data logs . . . . . . . . . . . . . . . . . . .
8.2.1 Data logging with a laptop . . . . . . . . . . . .
8.2.2 Data logging with the SD card . . . . . . . . .
8.2.3 Downloading SD data logs . . . . . . . . . . .
8.2.4 SD card error codes . . . . . . . . . . . . . . .
8.2.5 Data log bit fields . . . . . . . . . . . . . . . . .
8.2.5.1 CEL status . . . . . . . . . . . . . . .
8.2.5.2 Engine . . . . . . . . . . . . . . . . .
8.2.5.3 Port codes . . . . . . . . . . . . . . .
8.2.5.4 Status codes . . . . . . . . . . . . . .
8.3 Tooth / trigger logger and troubleshooting RPM issues
8.3.1 Lost sync numbers . . . . . . . . . . . . . . . .
8.3.2 Using the diagnostic logger . . . . . . . . . . .
8.3.3 Tooth logger . . . . . . . . . . . . . . . . . . .
8.3.4 Trigger logger . . . . . . . . . . . . . . . . . . .
8.3.5 Composite logger . . . . . . . . . . . . . . . .
8.3.6 Sync error logger . . . . . . . . . . . . . . . . .
8.3.7 Example logs . . . . . . . . . . . . . . . . . . .
8.4 Communication issues . . . . . . . . . . . . . . . . . .
8.4.1 USB driver software . . . . . . . . . . . . . . .
8.4.1.1 Windows drivers . . . . . . . . . . . .
8.4.1.2 Linux drivers . . . . . . . . . . . . . .
8.4.1.3 MacOS drivers . . . . . . . . . . . . .
8.4.2 Additional diagnostics . . . . . . . . . . . . . .
8.4.2.1 Portcheck . . . . . . . . . . . . . . . .
8.4.2.2 Loading firmware . . . . . . . . . . .
8.5 Loading or upgrading firmware . . . . . . . . . . . . .
8.5.1 Windows firmware loader . . . . . . . . . . . .
8.5.2 Linux firmware loader . . . . . . . . . . . . . .
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1 Introduction
1.1 Overview
Congratulations on your purchase of an MS3-Pro! The MS3-Pro is based on the proven MegaSquirtIII sequential ECU, but we have combined parts originally spread across five separate circuit boards
into a single, compact, weather resistant package. We’ve also made dozens of small tweaks to the
design to maximize reliability, improve noise resistance, and decrease power consumption.
This manual is based on the 1.3.1 and later firmware. Earlier documentation can be downloaded
at DIYAutoTune.com.
1.1.1 Warning labels
Everything comes with warning labels. Lets get these out of the way.
All parts are sold for OFF ROAD RACE-ONLY ground-vehicle use only, or vehicles that predate any
federal and state emissions control requirements. Aftermarket EFI/EMS systems are not for sale or
use on pollution controlled vehicles. Alteration of emission related components constitutes tampering
under the US EPA guidelines and can lead to substantial fines and penalties. Your state/district may
also have specific rules restricting your tampering with your vehicle’s emissions system. In short, as
DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
Page 11
1.2 MS3-Pro components
1 INTRODUCTION
stated before, our official policy has to be RACE or OFF-ROAD USE-ONLY in ground based vehicles
ONLY.
Race parts are inherently dangerous and may cause injury or damage if improperly modified or
altered before use. DIYAutoTune.com will not be held liable for and will not pay you for any injuries
or damage caused by misuse, modification, redesign, or alternation of any of our products. DIYAutoTune.com will not be held in any way responsible for any incidental or consequential damages
including direct or indirect labor, towing, lodging, garage, repair, medical, or legal expense in any
way attributable to the use of any item in our catalog or to the delay or inconvenience caused by the
necessity of replacing or repairing any such item.
1.1.2 Technical support
DIYAutoTune.com’s technical support team can be reached by email at [email protected]
If you are having difficulty with a particular issue, we recommend sending a data log of the problem
and a copy of your tune file with the email, as these are often helpful for resolving issues.
DIYAutoTune.com continuously maintains this manual; please use the contact address above if
you find any errors or sections that need to be cleared up.
1.1.3 Copyrights
This manual contains content copyright 2013-2015 Bruce Bowling, Al Grippo, James Murray, Ken
Culver, Jerry Hoffmann, and Matt Cramer. You may share this file in its unaltered form or print out
copies for your own personal use. For permission for other uses, contact DIYAutoTune.com support
at the link above.
1.2 MS3-Pro components
1.2.1 MS3-Pro Engine Control Unit
This ECU controls fuel, ignition, and many other engine functions. The internals are covered in detail
in section 3. Features 10 fuel outputs, 8 spark outputs, fuel pump control, one stepper motor driver,
and 6 different general purpose outputs.
1.2.2 Wiring harness
There are two separate components to the wiring harness, one with a white connector and one with
a gray connector. They plug into the matching colored connectors on the ECU. These connectors are
keyed so that they will not latch if you plug the wrong colored connectors in.
Wiring harnesses are available in 8’ (2.4 m) and 18” (50 cm) versions, as well as a connector
package for those who wish to build a harness completely from scratch.
1.2.3 Tuning cables
The MS3-Pro supports tuning via both USB and RS232. Both cables are included with a standard
wiring harness package; the connectors they plug into are inline style ones that are part of the wiring
harness, rather than separate connectors on the ECU. Replacement cables are available from DIYAutoTune.com.
DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
Page 12
1.3 MS3-Pro accessories
1 INTRODUCTION
1.3 MS3-Pro accessories
1.3.1 Sensors
The MS3-Pro can work with most OEM temperature, MAP, MAF, and throttle position sensors, as long
as you’re able to get the required information on the sensor’s output curve. This is covered in greater
detail in section 4, Wiring. But if you want a set of sensors that are known to work great with the MS3Pro, can be bought at a reasonable price, and are easy to find direct replacements, DIYAutoTune.com
carries GM temperature and MAP sensors.
1.3.2 QuadSpark
The MS3-Pro uses logic level spark outputs. These can be used with DIYAutoTune.com IGN-1A race
coils or OEM coils with integrated ignition modules, such as GM LS series coils, Toyota 1ZZ coil on
plug coils, or the pencil coils on VW / Audi 1.8 Turbo motors. They also work with most OEM ignition
modules. Some manufacturers, particularly Ford, Chrysler, and BMW, frequently build the ignition
module into their ECUs. If you have coils which do not have then ignition modules built in, and do
not have a separate ignition module, DIYAutoTune.com manufactures their own 4 channel ignition
module, the QuadSpark. This module can drive up to four ignition coils using Bosch BIP373 power
transistors.
1.3.3 Ignition coils
DIYAutoTune.com carries several ignition coils as well. The IGN-1A has a built in ignition module
and can be wired directly to the MS3-Pro. All other coils require the QuadSpark or other external
ignition module when used with MS3-Pro. Coils that DIYAutoTune.com offers include the IGN-1CD
for capacitive discharge ignitions, the IGN-4 four tower coil pack, the IGN-6 six tower coil pack, and
IGN-1FD coils for mounting directly to the spark plugs.
1.3.4 CAN-EGT thermocouple interface
Thermocouples put out a faint voltage that requires an amplifier circuit to get an accurate reading. The
CAN-EGT includes amplifiers for up to eight of these sensors, which can be used to measure exhaust
gas or cylinder head temperature. The CAN-EGT module then transmits the temperature data to the
MS3-Pro over a CAN network to avoid the inaccuracies of using a digital to analog conversion circuit.
The MS3-Pro can use this both for data logging and for safety shutdown features if the exhaust gas
temperatures go too high under load.
The CAN-EGT module can also gather data from the digital output on up to eight separate Innovate
Motorsports LC-1, LM-2, or MTX-L wideband controllers and transmit this information to the MS3-Pro.
Using this allows the MS3-Pro to run separate wideband O2 correction for all cylinders.
1.3.5 MicroSquirt
The MicroSquirt was originally intended as a fuel and ignition controller for powersports applications,
but its CAN network capabilities and easily reprogrammed firmware allow it to be configured for other
functions. Current release firmware allows it to be used as a transmission controller for applications
including GM 4L60E and 4L80E transmissions. The CAN bus allows you to view the MicroSquirt
transmission control data through TunerStudio as if the MS3-Pro and MicroSquirt are a single control
unit with a single point of tuning.
DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
Page 13
1.4 Tools
1 INTRODUCTION
1.3.6 Part numbers
Replacement parts
Component
DIYAutoTune.com part number
ECU
MS3Pro-ECU
Case O-ring seal
MS3Pro-Oring
8’ wiring harness
MS3Pro-Harn8
Harness connector package MS3Pro-AMPSEALS
Tuning cable (USB)
MS3TuneCable
Tuning cable (RS232)
MS3Pro-RS232Cable
Battery
BR-1225
Internal fuse
0454.500MR
SD card
SD-8G
Recommended accessories
Component
DIYAutoTune.com part number
Intake air temperature sensor with connector IATwPiggy
Coolant temperature sensor with connector
CLTIATwPiggy
QuadSpark four channel ignition module
QuadSpark
3 bar MAP sensor
GM3bar-map
Pigtail connector for MAP sensor
GM3bar_piggy
4 way stackable fuse block
Fuseblock-4
1.4 Tools
As a general rule, you’ll want to have the following tools and supplies on hand for a successful MS3Pro installation:
• Multimeter
• Laptop (the MS3-Pro software supports Windows, Linux, or Mac OS)
• Screwdrivers
• Soldering iron, solder, and heat shrink tubing (if joining wires by soldering) or crimp connectors
and crimp tool
• Wire cutters
• Wire stripping tool
• Timing light
• Wideband O2 sensor and controller (not needed for permanent installation, but useful for tuning)
• Electrical tape
• Vacuum tubing
DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
Page 14
2
INSTALLING SOFTWARE
2 Installing software
The MS3-Pro comes with a software installation CD that includes the following programs:
• TunerStudio. This is the main program you’ll use to connect to the MS3-Pro. It is used to
configure the MS3-Pro’s settings, tune the MS3-Pro, record data logs on the laptop, and retrieve
internal data logs.
• MegaLogViewer. This is an analysis program which can play back data logs and display the
data in both line graph and scatter plot format. It can also modify tune files based on information
recorded in data logs.
• Firmware loading utility. This is used to update firmware or for certain diagnostics.
Depending on your computer’s settings, the software may automatically install when you insert the
CD into your computer. If it does not, open the CD drive and double click the Setup.exe file on the
CD. Follow the installation prompts, and the software should install in just a couple minutes.
The tuning software can run on most versions of Windows, as well as Linux and Mac OS.
Both TunerStudio and MegaLogViewer have registered versions. To unlock the registered version, use the serial number code on your MS3-Pro. This appears on a label on the underside
of the box as well as on a tag on the back of the MS3-Pro. You will enter the serial number at
https://www.efianalytics.com/register/registerCoupon.jsp as a “Coupon code provided by dealer” to
obtain a registration key.
2.1 TunerStudio
2.1.1 Start screen
Once TunerStudio opens, you will be presented with the start screen as shown below.
DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
Page 15
2.1 TunerStudio
2
INSTALLING SOFTWARE
At this point, you’d normally use the screen to create a project or open one; this will set up TunerStudio with the configuration it needs to communicate with your ECU or allow you to view tune files
offline. You can create or open a new project under the file menu (1), or use this menu to open a new
tune for offline viewing. There are also command links to create a new project (2) or open a recent
project (3).
The Help and Support button brings up links to documentaion and support forums for the MS3-Pro
as well as other systems in the MegaSquirt line.
Note that if you open a tune file from this screen, it will go into a temporary project and TunerStudio
will not connect to the MS3-Pro until you create or open a project for connecting to the MS3-Pro.
2.1.2 Creating a project
Selecting “New Project” from the File menu opens a wizard to create a new project. It will bring up a
screen like the one below. At this point, you will want to have the MS3-Pro powered up (see section 4
for wiring details) and connected to the laptop with either the USB or RS232 cable. The MS3-Pro will
need to be powered through the 12 volt supply; it cannot be powered off the laptop.
DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
Page 16
2.1 TunerStudio
2
INSTALLING SOFTWARE
You can enter a name for the project in (1). Next, click the Detect button (2). TunerStudio will
detect what firmware is on your MS3-Pro. If it does not have a definition file, it will prompt you to
download one from the Internet, which TunerStudio will handle automatically for any standard release
version of the MS3-Pro firmware. You can also enter notes about this project in (3).
Clicking Next will bring up a screen where you can select project specific settings.
The exact settings shown will depend on your firmware. These settings are covered in more detail
in section 5.1.
Clicking Next will bring up a communications test screen.
DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
Page 17
2.1 TunerStudio
2
INSTALLING SOFTWARE
Driver options include:
1. RS232 serial. Use this for connecting to the MS3-Pro’s RS232 port without a USB adapter.
2. USB and wireless. This setting can be used with a Bluetooth adapter, the MS3-Pro’s internal USB port, or DIYAutoTune.com’s USB-2920 adapter on the MS3-Pro’s RS232 port. This
supports several connection types:
(a) RS232 Serial Interface. Use with USB adapters not sold through DIYAutoTune.com.
(b) FTDI - D2XX Driver. Use with the MS3-Pro’s internal USB port, DIYAutoTune.com’s USB2920 adapter, or other USB converters using a FTDI chipset.
(c) TCP/IP - Wifi Driver. Use with WiFi to serial adapters.
3. RS232 Alternate Blocking. This one was interoduced as an alternate mode for USB adapters
with a Prolific chipset, which can be troublesome with standard RS232 settings.
4. Aggressive Driver Reinitialize. Re-initializes the port every time you connect. Use if you have
a Bluetooth adapter that fails to reconnect. Most applications do not need this.
5. K-Line Driver. Not used with MS3-Pro.
Note that some of these options may be removed in future TunerStudio releases. Many of them were
developed as workarounds for specific issues, and future software upgrades may render several of
these unnecessary.
MS3-Pro normally runs at a 112500 baud rate.
After clicking Next, TunerStudio’s final project setup screen lets you select a gauge display.
DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
Page 18
2.1 TunerStudio
2
INSTALLING SOFTWARE
This display will show the gauges and indicators cycling through their range of readings. There are
several ready to run gauge options that you can select from the drop down menu at the top. Checking
the “other” box allows you to load custom dash files. You can edit any gauge cluster once the project is
opened, or load an alternate gauge cluster. Click “Finish” to confirm your gauge selection and launch
the new project.
2.1.3 TunerStudio main screen
Once you’ve made a project, TunerStudio will bring up its main screen.
DIYAutoTune.com MS3-Pro manual version 1.036, firmware 1.3.4, 6/10/2015
Page 19
2.1 TunerStudio
2
INSTALLING SOFTWARE
The screen is divided into several sections.
• The title bar at the top displays the current TunerStudio version, the project name, and when
connected to the MS3-Pro, the firmware version.
• The menu bar at the top deals mostly with TunerStudio functions, such as loading and saving
files. They also allow for calibrating the sensors.
• The large row of buttons bring up menus to access the settings in the ECU.
• The row of tabs below the buttons lets you select four different screens:
– Gauge Cluster: Displays basic information about the sensor readings, ECU calculations,
and status.
– Diagnostics & High Speed Loggers: These are used for various specialized troubleshooting
functions; see section 8 for more detail.
– Tune Analyze Live! Tune For You: This allows TunerStudio to recalculate new fuel tables
based on oxygen sensor feedback.
– Notes: A text editor for taking notes.
• You can change any gauge or indicator in the cluster by right-clicking on it and swapping it to a
different function.
• There is a second set of tabs at the bottom of the gauge cluster that allows you to set up multiple,
separate gauge clusters. Click on the rectangular icon to create a new cluster.
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3 MS3-Pro hardware
3.1 Overview
The MS3-Pro is a full standalone ECU with everything you need to run sequential fuel injection on up
to 12 cylinders. This ECU is based on the previous MegaSquirt-III design and runs similar code, but
we’ve miniaturized the system to fit into a smaller package, and put it in a waterproof enclosure with
high current, vibration resistant AMPSEAL connectors. Here are the MS3-Pro’s specifications.
Hardware features:
• Freescale MC9S12X 16 bit, 50 MHz asymmetrical dual core processor
• 10 saturated injector drivers
• 8 logic level ignition outputs
• 3 high current (5 amp) general purpose outputs - 2 can be reconfigured as additional injector
drivers
• 3 medium current (3 amp), high frequency general purpose outputs
• 1 stepper H-bridge driver
• Camshaft and crankshaft differential inputs - supports VR, Hall effect, and optical input
• 12 volt tach output
• Fuel pump output
• 8 analog inputs (5 dedicated sensor inputs, 3 general purpose)
• 5 general purpose on/off or frequency inputs
• 2 digital I/O logic inputs
• 2 knock inputs
• RS232, USB 2.0, and CAN communication
• Onboard SD card for internal data logging
• Internal ECU temperature sensor
• Real time clock
• Temperature range: -30 to +80 degrees C (-40 to +85 without battery for real time clock)
• Minimum supply voltage: 6 volts
• Maximum supply voltage: 22 volts before triggering overvoltage protection circuits
Software features:
• Supports speed density, alpha-N, or MAF based fuel and spark tables
• 1 microsecond injector pulse width resolution
• Tables for nonlinear injector behavior at small pulse widths
• Allows blending multiple load types, including specialized mode for independent throttle bodies
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• Supports a wide variety of OEM cam and crank position sensors
• Individual cylinder trim tables for fuel and ignition
• Accelerator pump or model based acceleration enrichment
• Closed or open loop idle speed control
• Closed or open loop boost control with gear or speed based tuning options
• On/off or closed loop continuously variable valve timing control - supports up to 4 channels
• On/off or progressive nitrous control
• Traction control
• Rally anti-lag
• Rotary support - can run up to 4 rotor engines with separate leading and trailing spark tables
• Staged injection
• Table switching
• 16 x 16 fuel and spark tables - can be reconfigured to function as 30 x 16 or 16 x 30 by switching
tables based on RPM or load
• 2 or 3 step rev limiter with no-lift shifting
• Wideband AFR target tables
• Flex fuel sensor input
• Allows repurposing injector or ignition outputs as general purpose outputs, or high current outputs as injector drivers for 12 cylinder sequential applications
• Real time barometric correction
• A/C and cooling fan control with idle compensation
• Safety shutdown based on AFR or EGT input
• Motorcycle shift cut
• 3 high current general purpose outputs
• 3 high frequency general purpose outputs
The MS3-Pro’s nylon case is somewhat unusual in a world of aluminum cased aftermarket ECUs. You
may be wondering how it can dissipate heat. Our strategy for heat management is simple: You don’t
need to dissipate heat if you don’t make heat in the first place. The MS3-Pro uses a power supply
optimized for high efficiency, and if you want to use circuits that generate large amounts of heat like
peak and hold injector drivers, they can be ordered as an external box. The plastic case is the same
grade of nylon used in many OEM ECUs and other underhood components.
Most of how to set these inputs up is covered in the wiring guide, but for those who want more
details on the circuits used in the MS3-Pro, here they are. (Most users can skip straight to Section 4
and start wiring the unit up, but for those who want to know the full details, here they are!)
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3.2 Inputs
3.2.1 Engine speed
The MS3-Pro uses a Maxim MAX9926 adaptive differential conditioner for engine RPM. This circuit
can accept input from variable reluctor, Hall effect, or optical sensors, and the input’s absolute maximum rating is 400 volts. The input circuit cannot be triggered off the negative terminal of an ignition
coil - this may damage the circuit. For fuel only installations, you will want to use a 12 volt tach signal,
like the one off an MSD ignition box.
Some spark modes, discussed in the ignition section of the manual, use the digital I/O channels
as well. These come into play for systems that either use very high frequency signals (such as the
Nissan or Optispark optical systems), require more than two sensors for engine position (such as the
Audi “tri-tach” system), or use more than one channel of variable valve timing.
3.2.2 Temperature inputs
The IAT and CLT inputs are designed to accept input from a negative temperature coefficient thermistor. Simply put, this is a sensor that is a type of resistor that changes resistance with temperature,
and the resistance goes down as the temperature goes up. The default settings are for the sort of
GM sensors that are something of an industry standard in the EFI world, but you can calibrate it for
other sensor types through TunerStudio. These incorporate a 2,490 bias resistor that connects the
sensor output to 5 volts. The sensor acts as a resistor to ground, reducing the voltage from 5 volts.
The higher the temperature, the more the sensor will pull the voltage down.
A third temperature input monitors ECU internal temperature. This sensor cannot detect individual
hot spots, but if you are installing this under the hood or in other applications where you are concerned
about exceeding its internal temperature limit, this will let you log and view how hot the MS3-Pro is
getting.
3.2.3 Throttle position
This input can accept signals in the 0 to 5 volt range and will work with almost any potentiometer type
TPS. If this is not used, you should connect this input to the sensor return.
3.2.4 O2 sensor input
This input is also 0 to 5 volts. It can be used with either narrow band O2 sensors or accept an analog
output from a wideband O2 sensor controller. It will not interface directly with a wideband O2 sensor,
but it is compatible with most external wideband controllers, including Innovate, AEM, Zeitronix, PLX,
and 14point7.
The three general purpose analog inputs may also be configured as additional O2 input channels
and work in the same way when set up as O2 inputs.
3.2.5 MAP sensor input
This input works with 0 to 5 volt MAP sensors, and can also be used with 0 to 5 volt mass air flow
sensors. The MS3-Pro does support frequency based MAP and MAF sensors, but not on this wire their signals need to be connected to a Digital I/O port.
3.2.6 General purpose analog inputs
These inputs can accept a 0 to 5 volt signal from a variety of sensors, which can be used for barometric
correction, O2 correction, an alternate load sensor (such as running a MAP and a MAF sensor at the
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same time), or simply for data logging additional sensors such as oil or fuel pressure.
3.2.7 Knock input
The MS3-Pro employs a Texas Instruments TPIC8101 knock sensor interface chip. This can use
either one or two knock sensors, and incorporates a built in, software adjustable bandpass filter. The
interface allows you to adjust the triggering threshold as a function of RPM and detect knock only at
specific crank angles so as to filter out noise occurring when the piston is in a position where it can’t
possibly be detonating. The MS3-Pro supports cylinder by cylinder knock detection and can identify
which cylinder is knocking by crank angle.
3.2.8 Digital I/O channels
There are several channels that support on/off inputs. The Digital Switched In wires can use an on/off
switch to ground. The Digital Switched 12V In line is triggered by 12 volts instead. There are also
three digital inputs capable of receiving high frequency signals, which can be used for speed inputs,
frequency based MAF or MAP sensors, or a number of other functions.
3.3 Outputs
3.3.1 Injector outputs
The injector outputs are limited to 5 amps per channel, with thermal shutdown protection. These can
drive one or two high impedance injectors on each output, but will not directly run low impedance
injectors. We recommend our eight channel Peak and Hold Injector Driver Board for use with low
impedance injectors. Unused injector outputs may be used for on/off outputs.
3.3.2 Ignition outputs
The MS3-Pro uses 5 volt, logic level ignition outputs with a high side driver circuit. These will drive
most factory ignition modules and coils with built in ignitors. For use with coils that lack built in ignition
modules, we recommend the QuadSpark external ignition module. Note that these outputs will not
trigger an MSD ignition box or a Ford TFI. The tach output (see below) can be reassigned to function
as a spark output when using these types of external ignition modules. Do not connect the MS3-Pro
ignition outputs directly to the negative terminal of an ignition coil; this can result in damage to the
MS3-Pro. Maximum current is 200 mA per ignition output channel, and pushing the output beyond
this amount of current can damage the output channel.
Unused ignition outputs may be used as on/off outputs, although their low current capacity means
we do not recommend using them for anything other than logic level devices or LED lights. Do not
use these outputs to drive relays directly or use them for anything that needs a ground for triggering.
3.3.3 High current outputs
These are ground switched outputs with a maximum current of 5 amps, just like the injector output
channels (in fact, it’s the same transistor type). These can be run in an on/off fashion or use pulse
width modulation. Flyback voltage spikes are clamped at 36 volts to help the valve close rapidly. They
typically work well with boost control solenoids and nitrous solenoids, which cycle fully off and fully
on.
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3.3.4 PWM medium current outputs
These are ground switched outputs, maximum current 3 amps. They are optimized for valves which
use pulse width modulation to hold them in an intermediate position instead of pulsing on and off.
Flyback spikes are clamped at battery voltage, which causes the valve to close more slowly. Common
valves that would use these outputs include idle air control valves and variable valve timing oil control
valves. They can also be used as an on/off signal. The fuel pump uses a similar circuit, although it
does not use PWM.
Note: Any device connected to these outputs must be set up so that it is powered off when the
ECU is shut down. Relays or solenoids connected to these outputs can back feed power into the MS3Pro if the relay coil or solenoid winding receives power with the key on. Wire any device connected to
these outputs to switched 12 volt power.
3.3.5 Tach output
This output can be used to produce a 12 volt square wave signal. It can also trigger certain ignition
modules such as an MSD 6AL or a Ford TFI, or be used as a general purpose on/off output. When
used as an on/off output, it can sink up to 1 amp.
3.3.6 Stepper motor control output
The MS3-Pro has one stepper control output, with a maximum current of 750 mA per channel. This
one is intended to drive a stepper idle air control valve. However, its outputs can also be used as
a tach signal or general purpose on/off outputs. When used as an on/off output, the device can be
treated as two separate paired low / high side drivers. The A output of either side is high when it
is turned on, while the B output will sink current to drive a relay or solenoid. Turning the output off
reverses the pattern if the other output is on. If both outputs are off, all four outputs will be floating
and neither sink nor source current.
3.4 Communications lines
3.4.1 RS232
RS232 is your old fashioned serial connection. This is brought out to a 4 piece Weather Pack connector in the harness, which connects to a cable that plugs into a 9 pin serial port on a laptop. RS232
is more noise resistant than USB, and if your laptop supports this, we recommend using it. Do not
attempt to plug the RS232 connection into any sort of 15 or 25 pin connector - these are usually for
VGA displays or joysticks. Some third party devices such as the Racepak data acquisition setup also
use the RS232 connection.
3.4.2 USB
The MS3-Pro features one USB output channel that allows it to communicate with a laptop.
3.4.3 CANbus
The CANbus wires are a communications network that allow the MS3-Pro to talk to other CAN enabled
modules. Note that not all CAN enabled devices will communicate with the MS3-Pro; CAN is a type of
hardware, and in addition to having the required hardware, the device you are attempting to connect
to the MS3-Pro must also be programmed to understand the type of messages the MS3-Pro sends.
Devices currently or soon on the market that can be connected to the MS3-Pro include:
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• MegaShift transmission controller and other devices in the MS-GPIO family
• DIYAutoTune.com CAN-EGT thermocouple interface
• JBPerf IO Extender
• AIMSport MXL and other display dashes
3.5 Maintenance inside the case
The MS3-Pro does not quite subscribe to the “no user serviceable parts inside” school of electronics
building. There are several items inside the MS3-Pro that are intended to be easy to service if the
need arises, although the battery should last for years and the other components will not need to be
replaced often.
3.5.1 Changing the fuses
The MS3-Pro uses two replaceable fuses. The F1 fuse protects the main input; if it blows, the entire
MS3-Pro will shut down. The F2 fuse protects just the TPS reference voltage output. If it fails, you
lose the reference voltage in the wiring harness, but all internal operation in the MS3-Pro will continue
as normal. If you have a fuse blow, please check to be sure there are no short circuits that may have
caused the problem.
To remove the fuses, use a needle nose pliers to pull the fuse out of its holder and press a new
fuse (available from DIYAutoTune.com) into its place.
3.5.2 Replacing the SD card
The SD card contains the MS3-Pro’s internal memory. This can be swapped out for a larger card if
needed. The card simply slides in until the retaining pin in the side of the SD holder moves out. You
do not need to push the card to eject it - simply pull it out. We use a blob of sensor-safe RTV to hold
the SD card in place against severe vibration.
3.5.3 Changing the real time clock battery
The MS3-Pro real time clock uses a lithium battery for maintaining its time and other data when the
ECU is powered down. The battery slips in with the positive (flat) side up. The MS3-Pro can use any
of the following batteries. Part numbers starting with BR can be used for -30 to +80 řC (-22 to 176 řF)
and should be used if mounting the MS3-Pro under the hood. If you do not anticipate exposing the
MS3-Pro to elevated temperatures, you may use the equivalent CR series batteries, which are rated
for use from -30 to + 60 řC (-22 to 140 řF).
• BR1216
• BR1220
• BR1225
• CR1216
• CR1220
• CR1225
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3.5.4 Improving the waterproofing
The case is O-ringed and can withstand immersion for 5 minutes, but is not intended for continuous
immersion out of the box. If you need more water protection - for underhood use, boats, or vehicles
that lack an enclosed passenger compartment - we recommend sealing the O-ring with a continuous
bead of sensor safe RTV silicone, and replacing the silicone every time the case is opened.
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4 Wiring
First, some general advice about wiring.
We use automotive grade, high temperature TXL wiring in our harness (it’s rated for up to 125řC),
but you should still do your best to keep it away from heat sources. Also take any potential sources of
mechanical damage into account - flip up headlight mechanisms, the side to side movements of the
engine on its mounts, etc.
Usually the biggest source of electrical noise isn’t RFI or other radio noise - it’s poor grounding or
having noise injected into the power wires by another device. The MS3-Pro needs to be grounded to
the engine block or cylinder head if at all possible; the battery negative terminal is often an acceptable
second choice. We do not recommend grounding the MS3-Pro to the chassis or sheet metal. You
may either crimp all ground wires to a single lug, or crimp the ground wires on the gray connector to
one lug and the single ground on the white one to a separate lug. The sensors need to be grounded
to the sensor return wire, which grounds them to the MS3-Pro. Grounding sensors to the engine or
body will create jitter from ground offsets.
You will also want to make sure the 12 volt power wire is clean. We recommend using one power
wire from the battery for the MS3-Pro EFI main relay, and a separate power wire to power the relay for
the injectors, fuel pump, and ignition system for maximum noise reduction. Fuel pumps and ignition
coils in particular tend to inject significant amounts of noise into their 12 volt supply wire. Also, putting
a capacitor (the points condenser out of an old fashioned points distributor will work) on the supply
line to the ignition coils can reduce the amount of noise they feed into the 12 volt supply.
You can start off a debate that goes on for hundreds of posts on an Internet forum over whether
it’s better to solder or crimp wires to join them. Either one can work very well if done right, and either
one can be unreliable if done poorly. It’s our experience that getting a good solder joint is more reliant
on good technique, which can still be done with cheap tooling, while a good crimp joint is more reliant
on good tooling. Either way, the joint needs to be sealed (such as with heat shrink tubing) to keep
out moisture and contaminants. Heat shrink tubing also provides some measure of protection against
vibration.
We designed the MS3-Pro’s power supply to run on a wide range of supply voltage. It can operate
on voltages as low as 6 volts to cover voltage dips during cranking, although if your voltage drops that
far, we’re not sure your battery is going to crank it over. The MS3-Pro has an input voltage limiting
circuit that clamps input voltage at 22 volts, and feeding it 22 volts for any sustained length of time will
blow the F1 input voltage protection fuse.
4.1 ECU pinout
The ECU uses two AMPSEAL connectors, where the pin numbers are molded into the connector
housing.
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4.1 ECU pinout
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White connector pinout
Pin
Function
Wire color
Stripe / shielding
1
High current out 1
Light green
None
2
High current out 2
Light green
Dark blue
3
Injector out J
White
Yellow
4
Injector out I
White
Gray
5
High current out 3
Light green
Red
6
CKP+
White
Shielded
7
Knock In 2
Orange
Red
8
5V+ VREF out
Gray
None
9
TPS in
Light blue
Shielded
10
MAT in
Orange
None
11
CLT in
Yellow
None
12
MAP in
Light blue
Dark green
13
Shield ground
Connects to shields
14
PWM / Idle Out 1
Light blue
None
15
CKPBlack
Shielded
16
Logic ground *
Black
None
17
RS232 ground **
Black
None
18
Sensor return
Black
White
19
Analog in 1
Light blue
Dark blue
20
Analog in 2
Light blue
Red
21
Analog in 3
Light blue
Purple
22
RS232 TX **
Black
Shielded
23
RS232 RX **
White
Shielded
24
Tach out
Light green
Purple
25
O2 in
Pink
None
26
CMP+
Yellow
Shielded
27
CMPRed
Shielded
28
Fuel pump relay out
Purple
None
29
PWM out 2
Light green
Pink
30
PWM out 3
Light green
Dark green
31
Knock in 1
Orange
Purple
32
Digital switched in 1
Gray
Orange
33
CAN L
Tan
Red
34
CAN H
Tan
None
35 12V+ switched power in
Red
None
* Both logic ground and power grounds must be connected to the engine block or cylinder head.
Do not leave the logic ground disconnected, as this may result in noise issues or improper operation.
** RS232 connections are brought to their own Weather Pack 4 pin connector and do not go into
the main harness.
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4.1 ECU pinout
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Gray connector pinout
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
Function
Injector out A
Injector out B
Ground
Injector out C
Ground
Injector out D
Ground
Injector out E
Ground
Injector out F
Injector out G
Injector out H
Spark out G
Spark out E
Spark out C
Spark out H
Digital frequency in 2
Ground
Digital switched 12V in
Digital switched in 2
Digital frequency in 3
USB power
USB ground
Spark out F
Spark out B
Spark out D
Spark out A
Digital frequency in 1
Digital switched in 3
Stepper IAC out 1B
Stepper IAC out 1A
Stepper IAC out 2A
Stepper IAC out 2B
USB DUSB D+
Wire color
White
White
Black
White
Black
White
Black
White
Black
White
White
White
Yellow
Yellow
Yellow
Yellow
Purple
Black
Gray
Gray
Purple
Red
Black
Yellow
Yellow
Yellow
Yellow
Purple
Gray
Blue
Blue
Green
Green
White
Green
Stripe / shielding
None
Orange
None
Light green
None
Pink
None
Red
None
Dark green
Dark blue
Purple
Dark blue
Red
Light green
Purple
Red
None
Dark blue
Red
Dark Blue
USB shield
USB shield
Dark green
Orange
Pink
No stripe
White
Purple
Red
White
White
Red
USB shield
USB shield
RS232 serial cable
The pin names are marked on the connector.
Weather Pack pin DB9 pin
A
5
B
9
C
2
D
3
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4.2 Wiring diagram
These show the basic connections - power, ground, fuel, ignition, idle control, and basic sensors.
Other inputs and outputs are covered in their respective sections.
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4.2 Wiring diagram
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4.3 Engine position sensors
The MS3’s CKP and CMP inputs use differential signal conditioners that can accept input from VR
(variable reluctor, also called a inductive pick-up or magnetic pick-up, although the latter is somewhat
confusing because Hall effect sensors are also magnetic), Hall effect, or optical sensors. We use
CKP (short for crankshaft position sensor) to mean the primary trigger. In most spark modes, this is
the signal the ECU relies on for most of its RPM and timing calculations. Although the abbreviation
implies the sensor should be on the crankshaft, in some cases, it’s actually in a distributor or on the
camshaft.
The CMP (camshaft position) signal is a secondary trigger. This is almost always on the camshaft
or distributor, although there are one or two setups that put this on the crank. The CMP sensor
generally provides supplemental information used to interpret the crank sensor readings, and its
accuracy is usually not as critical. Here are the rules we go by to identify which sensor is the CKP
and which is the CMP.
• If one sensor spins at crankshaft speed and the other spins at cam speed, the one that turns at
crank speed is the CKP and the one at cam speed is the CMP.
• On a GM Optispark and most Nissan optical cam sensors, the MS3-Pro normally uses a ring
with one slot per cylinder for primary engine operation. There is a ring of 360 slits that is used
for cranking and operation at very low RPM. Consequently, the one slot per cylinder sensor is
the CKP and the 360 slot ring is CMP. (Note that these use Digital Frequency In 2 for the CMP
sensor, as the regular CMP input is too heavily filtered to correctly handle this signal.)
• On almost all other setups with two sensors reading wheels spinning at cam speed, the sensor
that reads the wheel with the lowest number of teeth is CMP and the one with the most teeth is
CKP.
• Specific sensor setups that do not fall into any of these categories are covered in the ignition
set-up section of the manual.
Note that the conditioner circuit will invert the signal. We have left the settings unchanged because
a lot of other MegaSquirt installs use a conditioner that behaves in a similar way. So if you set the
ignition input capture to “rising edge”, that is the signal at the processor - it will actually be activated
when the signal coming in to the MS3-Pro transitions from high to low.
4.3.0.1 Variable reluctor sensors Variable reluctor (VR) sensors are similar to a guitar pick-up
coil. They have a magnet and a coil of wire which generates an A/C signal with a voltage that
increases with RPM. VR sensors do not have power wires as they generate their own voltage. On a
VR sensor, you will wire their two terminals to both of the CKP or CMP wires, as appropriate. Don’t
worry too much about getting it backwards - you can set the active edge in software.
The MS3-Pro package includes two 10K resistors sealed in red sealed tubing with yellow wire
leads. If you are using a VR sensor on a high tooth count wheel with missing teeth (Ford 36-1 and
Bosch 60-2 are two common examples) and lose sync as the RPM comes up, install one of the 10K
resistors in parallel with the sensor. This fixes the problem in most cases.
4.3.0.2 Hall effect and optical sensors Hall effect and optical sensors are a bit different. These
use a switching transistor and are powered from an external source (either 5 or 12 volts; if your sensor
can run on either, we recommend using 12 volts). Your typical sensor has three pins - the power wire
goes to a 12 or 5 volt feed, the ground wire goes to sensor ground, and the signal wire goes to CKP+
or CMP+ as appropriate. Do not use CMP- or CKP- with Hall effect or optical sensors. Leave
this wire disconnected and taped off.
Some sensors put out a square wave signal on their own, like the ones sold by DIYAutoTune.com.
Others switch from a ground output to a floating (undefined) output. The ones that behave this way
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4.4 Other sensors
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require running a 1K resistor from their power terminal to their signal terminal (called a pull-up resistor)
to work with MS3-Pro. If you’re not sure which sensor type you have, supply it with power and ground,
and check the voltage on its output wire when the sensor is both far away from any metal and touching
a piece of steel (note - do not use stainless steel for this test; some grades of stainless steel aren’t
magnetic.) If the output voltage stays at zero the whole time, you’ll need the pull up resistor; connect
the 1K resistor from the signal wire to the power wire. If it is at zero volts in one state and bounces up
to at least 5 volts in the other state, it doesn’t need a pull up resistor. The MS3-Pro package includes
two 1K resistors in blue sealed tubing with blue wire leads.
In some cases where a Hall effect sensor puts out 12 volts and the wiring harness has severe
noise issues, tying the CKP- or CMP- wires to the VREF output can reduce noise.
4.3.0.3 Points triggering and points replacement devices The MS3-Pro cannot trigger off the
negative terminal of an ignition coil directly. However, if you wish to lock out a points distributor
mechanism and let the MS3-Pro control the ignition, you can treat the points output as a Hall sensor
with a ground to floating output. You will need to connect a 1K resistor from a 12 volt source to the
points, and also wire the points to the CKP+ wire. Do not use the CKP- wire; tape it out of the way
safely.
Using a Pertronix Ignitor or equivalent is similar. With a Pertronix, connect the Ignitor’s red and
black wires with a 1K resistor, and leave the red wire connected to switched 12 volt power. Connect
the black wire to CKP+ and leave CKP- disconnected. Other modules may use different wire colors.
4.3.0.4 Fuel only with an MSD box or similar When MSD says that their orange and black wires
are the only wires that should be connected to the coil, they’re not kidding. You do not want to try
to get a tach signal from the coil by any means, including external adapter boxes. Instead, use the
ignition box’s tach output wire to the CKP+ instead if you are using a distributor advance mechanism
to control timing and just want the MS3-Pro to control fuel. Do not use the CKP- wire or the CMP+
and CMP- wires.
4.4 Other sensors
4.4.1 Temperature sensors
The MS3-Pro is designed to work with the type of sensor called a NTC thermistor. NTC stands for
negative temperature coefficient, and simply means that the resistance goes down as the temperature
goes up. This is how most automotive temperature sensors are set up, including the GM type sensors
available from DIYAutoTune.com. Normal automotive temperature sensors have two terminals. One
connects to the coolant temperature sensor or intake air temperature sensor input of the MS3-Pro.
The other one connects to the sensor ground wire. These sensors have no polarity and can be wired
either way.
There are two common variations on automotive temperature sensors. Closed element type sensors are resistant to water, oil, and other liquids. We recommend using this type for coolant. They
are not a good idea to use with air temperature, as they react slowly and are prone to absorbing heat
from the intake manifold. Open element sensors are better to use for air temperature. We recommend
mounting them upstream of the throttle body to avoid absorbing heat from the intake manifold, unless
you have a plastic intake manifold. If you are using a turbocharger or supercharger, the IAT sensor
must be mounted downstream of the compressor and intercooler (if used).
Sometimes you will find cars with one wire temperature sensors. We do not recommend using this
style as they are grounded through the engine block, and this will make for a noisy signal. A few cars
employ a three wire coolant temperature sensor. This sensor is typically two sensors in one housing
with a common ground.
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4.4.2 MAP sensors
Most MS3-Pro installations use a MAP sensor for load measurement. The MS3-Pro is designed to
use an external MAP sensor and can work with both frequency and voltage based MAP sensors. We
recommend GM MAP sensors, which are voltage based, because they are inexpensive and readily
available in several different maximum pressures. Be sure to select a MAP sensor that can read as
much pressure as you intend to run. On turbo cars, we recommend giving a slight amount of extra
room to allow the ECU to detect if the boost control has malfunctioned.
MAP sensor type Maximum boost level
1 bar
naturally aspirated
2 bar
14 psi
3 bar
29 psi
4 bar
44 psi
Install the MAP sensor with the hose fitting pointed downward, or at most, 30 degrees from vertical.
This will prevent oil or blow-by from accumulating in the sensor, which can damage its circuitry.
Here are what the pins on the GM MAP sensor do:
Pin Function
Connection
A
Ground
Sensor return
B
Sensor output
MAP in
C
Reference voltage 5V+ VREF Out
MAP sensors will have three pins unless they have some sort of additional sensor (usually a
temperature sensor) in the same package. The reference voltage connects to the MS3-Pro’s VREF
pin, and the ground pin to the sensor ground wire. For a voltage based MAP sensor, connect the
signal pin to the MS3-Pro’s MAP input wire. An additional MAP sensor may be used to measure
barometric pressure on one of the spare analog inputs. Frequency based MAP sensors such as
those used in Ford Mustangs must be wired to a Digital Frequency In wire instead of the MAP or
analog inputs. (You can also use the CMP+ wire for a frequency based MAP sensor, if you are not
using it for cam position.)
4.4.3 Throttle position sensor
The throttle position sensors used on most cars are potentiometer or variable resistance types, which
put out a voltage that increases as the throttle opens. The easiest way to check a TPS is to unplug it
and put an ohmmeter on its pins. Observe the resistance as the throttle opens and closes. Each pair
of pins will behave differently:
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The resistance between the VREF and ground pins will remain constant. The resistance between
the ground and signal pins will be low with the throttle closed and high with the throttle wide open.
The resistance between the VREF and signal pins will be high with the throttle closed and low with
the throttle wide open.
If your sensor behaves like this, it will be pretty straightforward to connect it to the MS3-Pro.
If the resistance jumps from infinite (or near infinite) to near zero, you have a switch type throttle
position sensor, or possibly a seriously defective potentiometer type TPS. These do not provide very
much information that MS3-Pro needs, as it can tell if you are at idle or full throttle by the MAP sensor
information. You can still use MAP based acceleration enrichment. If the TPS input is not used, this
wire should be connected to sensor ground.
4.4.4 Mass air flow sensors
Mass air flow (MAF) sensors provide a measurement of actual airflow through the intake system of an
engine. In its most basic form, the fuel required by the engine (in mass per second) is directly related
to the air flowing into the engine (in mass per second) so the MAF sensor should give a good basis
for the fuel equation. By comparison, Speed Density uses RPM, MAP, MAT and VE to estimate the
mass air flow. In practice, like any other sensor input the MAF has its own quirks and can suffer from
reversion effects (particularly on "cammy" engines) where the air flow gets measured twice.
MAF sensors have at least three wires: Ground, power supply, signal.
• The power supply is typically 12V and should be taken from a fused source from the main relay.
• Signal GND should connect to MegaSquirt sensor ground.
• If present, Power GND should connect to the engine block along with the other MegaSquirt
power grounds.
• With a voltage MAF, you may use the MAP signal wire or any of the three extra analog input
wires.
• With a frequency based MAF, you may use any of the Digital Frequency In inputs, or the CMP+
wire if you are not using it for cam position.
Here are some of the more commonly seen MAF pinouts.
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4.4.4.1 Ford 5.0 Mustang 4 pin oval connector MAF
Pin Function
Connection
A
Switched 12 volts
12 volt fused supply from main relay
B
Ground
To engine block
C
MAF signal ground MS3-Pro sensor return
D
MAF output signal
MS3-Pro MAP, Analog In 1, Analog In 2, or Analog In 3
4.4.4.2 Ford 5 pin rectangular connector MAF The rectangular connector MAF sensor has 5
pins denoted by A, C, D, and E, with the B pin missing:
Pin Function
Connection
A
Switched 12 volts
12 volt fused supply from main relay
C
Ground
To engine block
D
MAF signal ground MS3-Pro sensor return
E
MAF output signal
MS3-Pro MAP, Analog In 1, Analog In 2, or Analog In 3
4.4.4.3 Nissan / Infiniti Q45 MAF This is a popular MAF with many Japanese imports, although
its huge diameter (90 mm) and ability to handle large air flow volumes (by OEM MAF standards) would
work well on many smallblock domestic V8s as well. Note that the picture below uses non-stock wire
colors for clarity.
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4.4 Other sensors
Pin
B
D
E
Function
MAF output signal
Ground
Switched 12 volts
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OEM wire color
White
Black
Black / white
Connection
MS3-Pro MAP, Analog In 1, Analog In 2, or Analog In 3
MS3-Pro sensor return
12 volt fused supply from main relay
4.4.5 Oxygen sensors
The MS3-Pro can accept input from a narrow band O2 sensor directly; simply wire the narrow band
sensor signal to the O2 input wire on the MS3-Pro. Narrow band O2 sensors may have from one to
four wires. Here is what to do with the wires depending on the type.
• Single wire: The wire is the sensor signal and it grounds through the body.
• Two wires: One wire is the signal and the other connects to the sensor ground.
• Three wires: This is a heated sensor. In addition to the signal wire, there is a heater wire that
connects to a switched 12 volt source, and a ground wire which should be connected to the
engine block as the heater draws more current than we recommend applying to the sensor
ground wire.
• Four wires: These have a signal wire and a sensor ground wire which connects to the MS3-Pro
sensor ground wire. The two heater wires are normally the same color. One connects to a
switched 12 volt source and the other can be grounded to the engine block or chassis.
As a general rule, if the sensor has two wires that are the same color, these two wires are for the
heater, and may be hooked up either way. Bosch’s wire coloring system is the most common, and
looks like this:
Function
Color
Signal
Black
Sensor ground Gray
Heater
White
Heater
White
However, there are several other color schemes out there; if you run into a different set of colors,
consult a factory wiring diagram for your vehicle.
The MS3-Pro can also work with most aftermarket wideband oxygen sensor controllers. You will
need to install the controller according to the directions that came with it, and connect the controller’s
analog output wire to the MS3-Pro’s O2 input wire. If the wideband controller has a ground specifically
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for its analog output, it connects to the MS3-Pro sensor ground wire. Do not connect any wires labeled
“serial output”, “digital output” or similar to the MS3-Pro, or connect any other sort of wideband ground
to the MS3-Pro. Here is a list of what wire to use with common wideband controllers.
Controller
Analog output Analog ground
Innovate LC-1
Brown *
N/A
Innovate MTX-L
Yellow *
N/A
Innovate LM-2
Lime green*
Yellow*
AEM UEGO
White
N/A
Zeitronix ZT-2, ZT-3 White
Brown (ZT-2 only)
PLX SM-AFR
Gray
N/A
*Innovate systems have multiple analog outputs; this is the recommended default.
The above list is not intended to be a complete list of what wideband controllers will work with the
MS3-Pro; it will work with many other ones not listed. As long as the wideband has a 0-5 volt analog
output, and you can obtain the specifications for its output, you can make it work with the MS3-Pro.
Additional narrow band O2 sensors or wideband controllers may be wired to the spare analog
input wires.
4.4.6 Knock sensors
If you have a two wire knock sensor, connect one wire to the knock input wire and the other wire to
the sensor return. Some cars have three wire knock sensors; the third pin is a connection for a shield
on the wire. If you’re only using one knock sensor, connect it to Knock In 1. Knock sensors, like VR
sensors, generate their own voltage and do not require a power source.
4.4.7 Speed and gear sensors
The MS3-Pro can use analog or Hall effect speed sensors.
Analog speed sensors are rare, but put out 0 volts with the vehicle stopped, increasing to 5 volts
at some top speed. These may be wired to Analog In 1, 2, or 3.
Hall effect speed sensors are more common. These get 12 volts from the MS3-Pro’s main relay
or 5 volts from VREF, and have a ground wire that connects to the MS3-Pro’s sensor ground. The
output signal may connect to Digital Frequency In 1, 2, or 3, Digital Switched In 1, 2, or 3, or Digital
Switched 12V In. No pull up resistor is required. The MS3-Pro can use two separate speed sensors
for driven and non-driven wheels.
Some bikes are fitted with a Gear Position Sensor. This 0-5V analogue input can be used directly
to determine gear, and can connect to Analog In 1, 2, or 3. The MS3-Pro can also determine the gear
you are in by comparing the engine RPM and wheel speed.
When used with a MegaShift transmission controller, the MS3-Pro can read speed and gear information through the MegaShift over CAN. No additional sensor wiring is needed, other than the wires
for the MegaShift.
4.4.8 Generic on/off switches
There are several inputs the MS3-Pro can use as switch inputs for triggering launch control, nitrous,
table switching, or other functions. Valid inputs include Digital Switched In 1 through 3, Digital Frequency In 1 through 3, and Digital Switched 12V In. Digital Switched 12V In activates when connected
by a switch to a 12 volt source. All other on/off switch inputs activate when connected through a switch
to ground instead. The Digital Switched 12V In function is set up this way to allow using it to detect
when a nitrous system is energized and arm the system, but can be used for other functions as well.
Caution: Do not wire the Digital Switched 12V In wire directly to any input that is supplying power
to a trans brake or other high powered solenoid. This may result in damage to the input circuit.
Instead, use the 12 volt power to the solenoid to switch a relay to control an on/off input.
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4.4.9 Other sensors
You can connect any 0 to 5 volt analog signal to the Analog In 1 through Analog In 3 inputs. The
MS3-Pro software can use these for data logging or other functions.
4.5 Fuel injectors
Fuel injectors are pretty simple; one side gets switched, fused 12 volt power. The other side connects
to the MS3-Pro injector output. They are not polarized so it doesn’t matter which is which. Current
MS3-Pro settings have the firing order hard-coded in, so they always fire in alphabetical order.
If running sequential output on a 12 cylinder engine, High Current 1 and 2 fire the 11th and 12th
injectors in the firing order, respectively.
4.6 Ignition outputs
Ignition coils, as you probably know, require amps or tens of amps of current in order to work. The
signal from the MS3-Pro is a much lower-power "logic-level" signal - the kind of signal seen inside
computers. So some sort of device is needed to allow the weak logic-level signal from the MS3Pro to
drive the coils.
In other automotive scenarios, this might be done with a relay, which is commonly used to switch
a high-power signal from a source signal of lower power. But a relay isn’t suitable for driving a coil for
a number of reasons, so instead, there’s an electronic device called an ignition module, "ignitor," or
"coil driver" to do the job. A few manufacturers, such as Nissan, call the assembly a “power transistor,”
which more properly refers to the electronic component at the core of the coil driver device. Some
coils have the ignitor built in; those coils have more than 2 wires because of the extra functions they
contain. Simple coils without built-in ignitors usually only have 2 wires. (There are exceptions, like the
IGN-1 coils, which have an isolated secondary ground and use 3 wires.)
If you’re using a factory ignitor with matching factory coils, you can expect that the coils and
ignitors are designed to work together. If your coils require an ignitor but you do not have one, the
DIYAutoTune.com QuadSpark ignition module can drive most factory coils.
4.6.0.1 QuadSpark ignition module Here are the pins to use on the QuadSpark.
Wire color
Thickness
Connection
Yellow
20 gauge
MS3-Pro Spark Out A
White
16 gauge
Spark A to coil negative
Orange
20 gauge
MS3-Pro Spark Out B
Pink
16 gauge
Spark B to coil negative
Dark green 20 gauge
MS3-Pro Spark Out C
Light green 16 gauge
Spark C to coil negative
Blue
20 gauge
MS3-Pro Spark Out D
Violet
16 gauge
Spark D to coil negative
Black
4 x 14 gauge Ground to engine block or cylinder head
If using more than four channels of ignition output, you would use a second QuadSpark, wired up
like this:
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4.6 Ignition outputs
Wire color
Yellow
White
Orange
Pink
Dark green
Light green
Blue
Violet
Black
Thickness
20 gauge
16 gauge
20 gauge
16 gauge
20 gauge
16 gauge
20 gauge
16 gauge
4 x 14 gauge
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Connection
MS3-Pro Spark Out E
Spark E to coil negative
MS3-Pro Spark Out F
Spark F to coil negative
MS3-Pro Spark Out G
Spark G to coil negative
MS3-Pro Spark Out H
Spark H to coil negative
Ground to engine block or cylinder head
4.6.0.2 IGN-1A coil with built in ignition module The IGN-1A is a high powered coil with a built
in ignition module, capable of handling engines that make over 250 hp per cylinder. These can be
used both for coil per plug applications or with a distributor. These use a five wire connector. The
connector pins are designated with letters molded into the connector:
Connection letter Function
A
Spark out from MS3-Pro
B
Logic ground to sensor return
C
Secondary ground to engine block or cylinder head
D
Power ground to battery negative terminal
E
12 volt power
4.6.0.3 LS series coils The coils on GM’s LS series engines are a popular choice as they are
readily available, inexpensive, powerful, and have a built in ignition module. They can be wired directly
to the MS3-Pro. LS1 and LS2 coils use different connector designs, but the connectors are always
marked with small letters to indicate the function, and the function is the same on both:
Connection letter Function
A
Power ground to engine block or cylinder head
B
Logic ground to sensor return
C
Spark out from MS3-Pro
D
12 volt power
4.6.0.4 VW pencil coils VW four pin pencil coils appeared on the VW / Audi 1.8 Turbo from 2001
and later, and many other VW-Audi Group products. These can be driven directly from the MS3-Pro.
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4.6 Ignition outputs
Pin number
1
2
3
4
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Function
12 volt power
Ground to engine block
Spark out from MS3-Pro
Ground to engine block
4.6.0.5 MSD and other single channel capacitive discharge ignitions Capacitive discharge
boxes are a popular choice to deliver a strong spark when running a distributorless ignition is not an
option. Many of these are intended for an unusually high current signal instead of a logic level output.
To use one of these boxes, connect the Tach Out wire on the MS3-Pro to the ignition box’s points
trigger. The MSD 6A box used a white wire for this input, and most other CDI boxes have followed
their lead.
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4.6.0.6 Common firing orders
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4.7 IAC valves
IAC stands for Idle Air Control. These valves work like a small throttle under ECU control to allow
the MS3-Pro to adjust idle speed. Sometimes you will see these called an ISC valve, for Idle Speed
Control, or BAC, for Bypass Air Control. Idle air control valves come in several varieties. The MS3-Pro
supports most designs out there, with a few exceptions.
4.7.1 Stepper IAC valves
Stepping motors come in two varieties, permanent magnet and variable reluctance (there are also
hybrid motors, which are indistinguishable from permanent magnet motors from your MS3-Pro controller’s point of view). Lacking a label on the motor, you can generally tell the two apart by feel
when no power is applied. Permanent magnet motors tend to "cog" as you twist the rotor with your
fingers, while variable reluctance motors almost spin freely (although they may cog slightly because
of residual magnetization in the rotor). You can also distinguish between the two varieties with an
ohmmeter. Variable reluctance motors usually have three (sometimes four) windings, with a common return, while permanent magnet motors usually have two independent windings, with or without
center taps. Center-tapped windings are used in unipolar permanent magnet motors.
There are a variety of stepper motor types in use in OEM IAC systems. Most domestics use bipolar
stepper motors, while some Toyota and Mitsubishi engines use unipolar stepper motors. Either one
can run off the MS3-Pro.
For both permanent magnet and variable reluctance stepping motors, if just one winding of the
motor is energized, the rotor (under no load) will snap to a fixed angle and then hold that angle until
the torque exceeds the holding torque of the motor, at which point, the rotor will turn, trying to hold at
each successive equilibrium point.
Unipolar stepping motors (5 or 6 wire) are usually wired as shown in the schematic below, with a
center tap on each of two windings. In use, the center taps of the windings are typically wired to the
positive supply, and the two ends of each winding are alternately grounded to reverse the direction of
the field provided by that winding.
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Typical bipolar steppers have 4 leads, connected to two isolated coils in the motor. These are
the most common in automotive applications. Bipolar permanent magnet and hybrid motors are
constructed with exactly the same mechanism as is used on unipolar motors, but the two windings
are wired more simply, with no center taps. The leads to both coils are brought out to the harness with
4 wires. If you energize one coil the rotor will rotate to a position aligned with that coil. If you energize
the second coil the rotor will rotate a little bit to be aligned between the two coils. If you turn off the
first coil the rotor will rotate a little more to line up directly with the second coil. If you energize the
first coil again with the opposite polarity of the first time the rotor will rotate a little more, and so on.
The MS3-Pro controller applies pulses in a particular sequence to the four wires to produce rotation.
Each pulse results in specific amount of rotation of the motor . The motor can be made to spin either
direction by changing the polarity of the pulses.
On GM IAC steppers, the one coil usually has blue wires leading to it, the other coil has green
wires. The schematic below shows how such a motor is wired.
The picture below shows most of the common GM and Chrysler IAC valve pinouts and how they
wire to the MS3-Pro. The illustration is looking into the IAC valve itself, not the wiring on the harness
side.
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There’s no such thing as a stepper motor with less than four wires. If your IAC valve has two or
three wires, it is probably a PWM style valve, described below.
4.7.2 PWM IAC valves
A PWM style valve uses a solenoid that opens or closes the valve, and the ECU controls its position
by pulsing the solenoid coil off and on rapidly. These can sometimes be simpler to set up than a
stepper IAC valve, as the position is just a function of how much current flows through the coil. These
come in two varieties. One uses a single coil, which pushes the valve open (or, rarely, closed) when
the coil energizes. Another design has two coils, one of which pushes the valve open and the other
pushes it closed. The MS3-Pro can drive both sorts.
A single coil IAC valve will have two wires. One connects to switched 12 volt power; the other
connects to the MS3-Pro PWM / Idle Out 1 wire. Sometimes these valves, like injectors, have no
polarity. Other valves have a built in diode, and it is important with such a valve to make sure you
do not wire it backwards. Consult the wiring diagram for the car the valve came on if you aren’t sure
which terminal should receive power.
Two coil IAC valves have three wires. One terminal is for 12 volt switched power; the other two
connect to the MS3-Pro PWM outputs, one of which should be PWM / Idle Out 1 (you can specify
in the software which output closes the valve and which opens it). Usually, the center wire on the
connector gets 12 volt power. If you’re not sure which is the power wire, check with an ohm meter.
The resistance from the ECU connections to power will be one half the resistance from one ECU
connection to the other.
Note that PWM IAC valves must be wired in such a way that they do not receive 12 volts with the
key off.
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4.7.3 On/off IAC valves
Rare but supported. The MS3-Pro’s PWM / Idle Out 1 can drive an on/off idle solenoid directly if the
solenoid draws 3 amps or less.
4.7.4 Thermal IAC valves
These valves were used on some early Bosch L-Jetronic systems and are not controlled by the ECU.
They use a thermal element that warms up and reduces idle speed as they heat up. If you have such
a valve, power it from the fuel pump relay.
4.7.5 DC servo IAC valves (currently not supported)
This design incorporates a two wire DC servo with a three wire position sensor. We’ve only seen
them on a few Ford and Mitsubishi throttle body injected engines from the 1980s. The MS3-Pro does
not currently support this idle valve type.
4.8 Fuel pump relay
The MS3-Pro fuel pump relay output is a low side driver that supplies ground, not power. It can only
handle a maximum of 3 amps, so you will need to use this to turn on a relay to provide the fuel pump
with enough power. We recommend supplying the fuel pump relay with a separate source of 12 volt
power from the ECU main relay to minimize electrical noise. Do not wire a fuel pump directly to the
MS3-Pro. Also, do not wire the fuel pump relay coil in such a way that it receives 12 volts with the key
off, as this power can backfeed into the MS3-Pro and cause it to stay powered up when the ignition is
turned off.
4.9 Tach output
The tach output supplies a 0 to 12 volt square wave that is compatible with many factory tachometers
and nearly all aftermarket units. Just wire its output to the tach signal wire.
4.10 High current outputs
The MS3-Pro’s three high current outputs can be used to control devices that draw up to 5 amps.
These outputs are what are known as low side drivers; they provide a switched connection to ground.
The other side receives 12 volts, ideally only when the ignition key is on. Recommended uses besides
on/off output include nitrous control and running boost control solenoids, which pulse open and shut.
Note that any unused injector outputs can be used for the same on/off or low frequency functions
as the high current outputs; they have the same maximum current and basic design.
4.11 PWM medium current outputs
These outputs are low side drivers like the high current outputs, but can operate at a higher frequency
and have a maximum current of 3 amps. Devices connected to these outputs absolutely must not
receive power when the key is off, as the circuit used to clamp high frequency voltage spikes can
feed power back into the MS3-Pro’s power supply and prevent the ECU from turning on. Maximum
frequency is 1021 Hz. The high frequency outputs work best with valves that can stay in the middle
of their travel, like variable valve timing control valves and idle air control valves.
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4.12 Grounding notes
The MS3-Pro uses multiple ground planes to reduce noise. It is important that you connect both
the logic ground at pin 16 on the white connector and all the power grounds on the gray connector
to a solid, rust-free grounding point on the engine block or cylinder head. Grounding to the battery
negative terminal is also acceptable. Avoid grounding the MS3-Pro to the frame rails or sheet metal;
these points often have issues with rust and spot welds limiting how much current can flow through
them.
Leaving the logic ground disconnected can result in improper operation.
The MS3-Pro has a sensor ground pin on pin 18 of the white connector. All sensors except VR
sensors should be grounded to this pin. Do not ground the sensors to the chassis, engine block, or
other external point, as this can create noise issues.
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5
SETTING UP A BASIC CONFIGURATION
5 Setting up a basic configuration
5.1 Connecting the MS3-Pro to your laptop
1. Power up the MS3-Pro and plug it in to your laptop with either the provided serial or USB cable.
The MS3-Pro is not powered through the serial cable; it will need to be connected to a good
power and ground source to communicate.
2. Open TunerStudio. TunerStudio will check for available updates; if there is one, accept it and let
it install.
3. From the File menu, select "New Project".
4. You may enter a name to keep track of the project and a detailed description in the Project
Description field.
5. Click the “Detect” button. TunerStudio should automatically detect that you have an MS3-Pro
and what port it is using.
6. Clicking the Next button will bring up a menu of project settings.
7. Here are what the project settings do:
• Oxygen Sensor/Display - selects the default gauges for oxygen or lambda sensor (the
AFR/EGO settings must also be used to configure the firmware)
• Temperature Display - preferred temperature units
• CAN_COMMANDS - normally Deactivated. Only Activate this where you are connecting
to the MS3 over a CAN network instead of directly with USB or serial.
• EXPANDED_CLT_TEMP - normally Deactivated. Can be Activated for air cooled engines
that use a greater temperature range.
• MPH - speed units. Activated = mph. Deactivated = kph
• METRES - length units. Activated = metres. Deactivated = inches.
• INTERNAL_LOG_FIELDS - normally Deactivated. Allows developers to log special fields
into SDcard logs.
• PW_4X - normally Deactivated. Used in conjunction with the advanced firmware setting
to enable four times the injector pulsewidth on large industrial engines that use injectors
sized for operating below 2000 RPM.
8. When you are done with the project settings, click Next. This will bring up a page of communications settings.
9. The final screen for project setup is to select a dashboard view. It is safe to accept the default
and Finish. TunerStudio allows advanced users to create their own custom dashboard layouts.
10. At this point, you’re ready to start setting up the MS3-Pro to run your engine.
The first rule of tuning is that you do not want to tune from a blank file. You can either connect to the
MS3-Pro and retrieve the tune on it (this is done automatically) or open an existing tune file, but be
careful if you see this message:
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This means that you have no tune loaded. This is OK if you are just having a look, but do not try
to start a tune like this. TunerStudio will default to a table full of zeroed out values - or in some cases,
the numbers will be set to their lowest possible value. It’s not worth chasing down all the nonsense
values to turn this “blank file” into a real tune. Start with either the tune in the ECU or one of the
sample tunes provided in the software package.
We recommend that you do not have the ignition coils hooked up while doing a basic setup on the
MS3-Pro. During the setup stage, you will define what type of ignition hardware that you are using, but
if the ignition you have doesn’t work with the default settings, you may overheat your ignition module
and damage it before you are done with your setup.
5.2 Basic engine constants
First, we’ll go over the basic settings you need to go through for starting the engine. The following
are the most essential settings. We’ll come back and go over the other menu items later. The first
stop is under the Basic / Load Settings menu. Select Engine and Sequential Settings. Here is
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what the settings do.
• Required Fuel: This is your base pulse width. It is the amount of pulse width the engine would
theoretically need at 100 kPa and 100% volumetric efficiency. While you can enter it directly,
we recommend using the calculator that the “Required Fuel...” button pulls up. Here, you will
enter the engine displacement, number of cylinders, injector fuel rate, and air/fuel ratio. Usually
the air/fuel ratio should be stoichiometric for the fuel used, such as 14.7 for gasoline or 9.85
for E85 ethanol blends. Note that you will want to run this after entering the injector size and
displacement numbers, below.
• Control Algorithm - This setting controls the method with which engine load is calculated.
Engine load represents how hard the engine has to work and can be based on many factors
such as manifold pressure, throttle position, air mass, or combinations of these. Note that this
setting only sets the control algorithm for fuel injection and related settings; it does not set the
control algorithm for ignition and related settings. You may use different algorithms for different
tables. The following settings may be selected.
– Speed Density - Use the MAP (Manifold Absolute Pressure) sensor to determine load. In
this case, the vertical axis of any fuel table lookups is in kilopascals (kPa). The maximum
value reported by the MAP sensor (in non-turbo applications) will be the same as the
barometric pressure.
– Percent Baro - This setting is similar to the Speed Density setting in that the MAP sensor
is used to determine load. However, instead of directly using the manifold pressure, the
manifold pressure is divided by barometric pressure to give a percentage of barometric
pressure. This setting can be useful for those who regularly drive at high altitudes. It
ensures that regardless of barometric pressure, all table lookups operate over 0-100%.
For example, if barometric pressure is 80 kPa, and the engine is operating at 50 kPa, the
actual value used for table lookups is 50kPa/80kPa or 62.5%.
– Alpha-N - Use the throttle position to determine load on the engine. Be sure to calibrate
the throttle range using Tools -> Calibrate TPS before using this setting.
– MAF - Use the MAF sensor and related calculations to directly determine the amount of
fuel to inject. In this mode, the VE table is not used to determine the amount of fuel to
inject.
– ITB - This mode was created specifically for naturally aspirated engines running with independent throttle bodies. It combines alpha-n (at high engine loads) with speed density
(at low engine loads), using the load calculation that makes the most sense at each RPM.
For example, most ITB setups do not have good vacuum at idle or low RPM, and slightly
touching the throttle makes them lose all vacuum, but at higher RPM start to respond more
like a traditional single throttle body engine. This mode allows the use of speed density
at low engine loads and switches to alpha-n at high loads, with an adjustable switchpoint
curve over RPM.
• Squirts Per Engine Cycle - Only used when running batch fired injection. Determines the
number of times per engine cycle (two revolutions on a four-stroke engine) injectors are squirted
when in a batch injection mode. This setting has no effect when injecting sequentially.
• Injector Staging - This setting is used only in batch injection modes. It determines whether the
two injection channels are squirted at the same time, or in an alternating fashion.
• Engine Stroke / Rotary - Specify whether the engine is a four or two stroke piston engine, or
a Wankel rotary engine. The rotary mode allows for trailing spark outputs on Mazda and other
dual plug rotary designs.
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• Number of Cylinders / Rotors - Sets the number of cylinders for the engine. The MS3-Pro can
run sequential injection on up to 12 cylinders.
• Engine Type - Determines whether the engine is an even-fire engine or odd-fire engine. An
even fire engine is an engine where the crankshaft moves an equal number of degrees between
each cylinder’s top dead center (TDC). An odd fire engine may have a different number of
degrees between TDC on some cylinders when compared with others. You are only likely to
see odd fire settings on certain V6 models, “crossplane” inline fours and split crank parallel
twins (found on some motorcycle engines), and V type engines having less than 6 cylinders.
Normal V8, inline four, and inline six engines are all even fire.
• Engine Size and Injector Size are used for MAF fueling and the Required Fuel calculator.
• Main fuel outputs - This should be set to “Injector A, B...” Fuel for all normal MS3-Pro installs.
This is included to allow you to check tune files imported from standard MS3s. It can be set to
use only injector I and J, but this is mostly to maintain compatability with MS3 V3.0 / V3.57 tune
files.
• Sequential On - The injector sequencing may be set to three different modes.
– Off - Use batch injection. The channels are divided into two groups, and all injectors in a
group are squirted simultaneously. This mode would typically be used if your engine has
an ignition input like a HEI distributor that provides for no cylinder identification.
– Semi-Sequential - Injects once every rotation, firing injectors in pairs. The injectors are
timed, so you can set the angle at which they fire. Injectors should be wired in the same
manner they would be wired for fully sequential injection.
– Fully Sequential - Use fully sequential injection. In this mode, outputs A-H are squirted in
sequence, so care must be taken to use the correct wiring for the engine’s firing order. For
example, for a four cylinder engine with firing order 1-3-4-2, the following wiring should be
used:
∗
∗
∗
∗
Output A - Cylinder 1
Output B - Cylinder 3
Output C - Cylinder 4
Output D - Cylinder 2
• Angle Specifies - The MS3-Pro has a tunable injector timing table, and this setting determines
how the MS3-Pro interprets that table.
– End of Squirt - The angle specified in the injector timing table specifies the angle of the
end of each squirt. This should be used by most people for most engines.
– Beginning of Squirt - The angle specified in the injector timing table specifies the angle of
the beginning of each squirt.
– Middle of Squirt - You can also use the injector table to specify the mid-point of the injection
event if you find this easier to tune.
• Injector Trim - Turning this on allows adjusting the injectors separately using injector trim tables.
• Firing order - The firing order should be set to the firing order that your engine uses. It does
not affect the order in which the outputs are triggered. Instead it is used to associate an injector
trim table with a particular physical output so that when injector trim is applied, it is applied to
the correct cylinder. It is also used if closed-loop EGO is being done per-cylinder.
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5.3 Ignition settings
Next, proceed to the Ignition Settings menu and select Ignition Options / Wheel Decoder to set
up how the MS3-Pro gets its RPM input and controls the ignition.
Here are what the settings under this menu do. We’ll go over setting these up, then the next
subsection will cover the settings for specific engine modes.
• Spark mode - this sets the type of tach input pattern decoder to be used. Four of these modes
are generic, while the remainder of these are model specific ignitions. Here are the four generic
modes. The chart below shows what the model specific modes cover.
– Fuel Only: The ECU is not controlling ignition, and receives a tach signal of one pulse for
every ignition event.
– Basic Trigger: A simple distributor trigger setup where the ECU controls the ignition, but
receives one pulse per ignition event. Common examples include Ford TFI, GM computer
controlled HEI, and MSD’s “flying magnet” crank trigger.
– Trigger Return: Similar to Basic Trigger, but there is a Hall effect or optical distributor where
the leading edge of the signal is used to calculate timing when the engine is running, and
the trailing edge is used for cranking timing. Common in VW and other European Hall
effect distributors.
– Toothed Wheel: This is a user defined trigger wheel configuration. There are two basic
types: “Dual Wheel” mode has one trigger wheel with equally spaced teeth and a one tooth
sync signal, while “Missing tooth” mode has a wheel where most of the teeth are equally
spaced, but there is a gap of the width of one or two teeth. This wheel may or may not
be paired with a second sensor for cam sync use. Ford, Bosch, and Nippon Denso OEM
systems often use this mode. So do the common aftermarket dual sync type distributors.
Note that some modes in the chart below can be run without a cam sensor, but if the cam sensor is
omitted, the engine will not be able to run sequential injection or coil on plug.
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Spark mode
Basic trigger
Trigger return
Fuel only
Toothed wheel
EDIS
420A / Neon
36-2+2
36-2-2-2
Subaru 6/7
Miata 99-05
6G72
IAW Weber
CAS 4/1
4G63
Twin trigger
Chrysler 2.2 / 2.5
Renix 44-2-2
Suzuki Swift
Suzuki Vitara 2.0
Daihatsu 3cyl
Daihatsu 4cyl
VTR1000
Rover #1
Rover #2
Rover #3
GM 7X
QR25DE
Honda RC51
Fiat 1.8 16V
Optispark
Nissan SR20
Nissan RB25
LS1
YZF1000
Honda Acura
VQ35DE
Jeep 2000
Jeep 2002
Zetec VTC
Flywheel tri-tach
2JZ VVTi
Honda TSX / D17
Mazda6 2.3 VVT
Viper V10
Honda K24A2
HD 32-2
Miata 36-2
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Sequential capability
Only with Ford TFI signature PIP
No
No
Yes, with appropriate cam sensor
Yes, with appropriate cam sensor
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes, if cam sensor is used
No
Yes
Yes
Yes
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes, using MAP sensor
Yes
Common applications
Basic distributors - GM HEI, Ford TFI, MSD, some Bosch
1980s era VW distributors
Mechanical advance distributor
Many Ford, BMW, Toyota
Fords with external EDIS ignition module
1995-1999 Dodge Neon, Mitsubishi Eclipse 420A
Chrysler New Hemi and other 2003 and later engines
Mazda RX8, many Subarus after 2000
Subarus from 1990s through mid 2000s
1994-2005 Mazda MX5 Miata
Many Mitsubishi and Chrysler V6s
Ford Sierra Cosworth, many Fiat, Lancia
Mazda Protege optical distributor, Mitsubishi 4G91
Mitsubishi 4G63, 1990-1997 Mazda MX5 Miata
Motorcycles
Chrysler K-car 2.2 / 2.5 multiport and turbo
1987-1990 Jeep 4.0, many 1980s Renaults
Suzuki Swift GTI
Suzuki Vitara, Sidekick
Daihatsu 3 cylinder
Daihatsu 4 cylinder
Honda V-twin
Rover K-series
Rover K-series
Rover K-series
GM 60 degree V6, Saturn, 4.2 Atlas
Nissan QR25DE
Honda RC51, 2000-2005 S2000, CBR
Fiat 1.8 16V
GM LT1 and variants, Nissan / Infiniti VH45DE
Nissan SR20DET, CA18DET with coil on plug
Nissan Skyline RB series, 300ZX VG30DE
GM LS1 and variants
Yamaha YZF1000
Honda J series V6
Nissan VQ35DE V6
1991-2000 Jeep 4.0
Jeep 4.0 and 3.8 with distributorless ignition
Ford 2.0 Zetec with variable valve timing, Jaguar V8
1980s era Porsche and Audi
Most Toyotas with VVTi variable valve timing
Honda D17, K series, 2006 and later S2000
Mazda 2.3 with variable valve timing
Dodge V10 with JTEC ECU
Honda K24A2
Fuel injected Harley-Davidson V-twins
Flyin’ Miata aftermarket trigger
• Trigger Angle/Offset - There are three different ways this setting is used:
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– In Basic Trigger and Trigger Return, it specifies the engine angle BTDC that each trigger
pulse is received.
– In Toothed Wheel, it should always be set to zero - use tooth#1 angle instead.
– In other modes, this setting can make a +/- 20 degree adjustment to the preset timing
alignment.
• Angle between main and return - This is only used in CAS 4/1 mode and specifies the angular
length of each tooth.
• Oddfire first angle - For oddfire engines this specifies the angle the engine must rotate from
spark A output to spark B output.
• GM HEI/DIS, TFI, C3I options - Some distributor and related setups have a couple of extra
tricks that they use:
– Off: No additional spark outputs or cylinder identifications are used:
– GM Bypass on Spark B: On a computer controlled GM HEI or many GM distributorless
ignitions, this setting enables the "bypass" output on spark B. The bypass output allows
the module to control the timing during cranking. The ECU applies voltage to the bypass
wire after startup to take control of timing.
– Buick C3I: This uses a distributorless ignition which behaves like a GM HEI, but also includes a cam sync signal. Used with Toothed Wheel mode instead of Basic Trigger to
enable the cam sensor.
– TFI Non-Signature: Used with Ford TFI distributors where all trigger vanes are the same
length.
– TFI Signature PIP: This allows you use the cylinder identification feature on Ford Signature
PIP distributor, where one vane is shorter than the others. Signature PIP mode is used
with "Basic Trigger" and allows the MegaSquirt to use these distributors for sequential fuel.
• Oddfire phasing - Most oddfire engines, such as the Chevy V6, use alternate long/short angles
between cylinders. Yamaha Vmax and a couple other V-twins use a paired long/long/short/short
pattern. You can also define a custom pattern with four separate odd fire angles, for engines
where the odd fire sequence is really odd.
• Skip Pulses - This tells the code how many input pulses it should ignored before attempting to
match the input pattern. The default value of 3 is suitable for most applications. Increasing this
number can filter out RPM spikes right at the start of cranking, but setting this value too high will
delay startup. This setting is only used for startup and is ignored after the engine is running.
• Ignition Input Capture - Determines if the active edge is when the voltage on the RPM input
rises or falls. This must be matched to your tach input. If it is set incorrectly you can experience
timing drift with rpms or misdetection of missing teeth on a missing tooth wheel. The tooth
logger can be used to confirm polarity is correct. Note that for compatibility across several
different products in the MegaSquirt family, this name refers to the signal at the processor, not
the signal coming into the ECU. The MS3-Pro’s input conditioner will invert the signal. So if you
were using a Hall effect sensor where the voltage dropped from 12 to 0 volts, the MS3-Pro will
see this as a rising edge instead of a falling one. If using the Digital Frequency In pins for cam
input, the signal on the Digital Frequency In pins is not inverted.
When using a VR sensor, it’s important to set the correct edge, as one is more stable than the other.
Here is what a typical VR signal can look like:
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The MS3-Pro needs to be configured for rising edge in this instance as that matches the "sharp"
well defined zero crossing of the input signal. Triggering on the falling edge will result in a more
unstable signal.
• Spark Output - This setting is critical or you will damage your coils or ignition modules. Going
High means that the output goes high (5 volts) to dwell the coil, and then drops low to discharge
the coil. Going Low means that the output is held at 5 volts, drops to 0 volts to dwell the coil, and
then goes back to 5 volts to make the coil discharge. For 99% of installs using the MS3-Pro,
this should be set to "Going high".
• Number of coils - Specifies the type of ignition coils in use. The code automatically chooses
the number of outputs to use.
– Single coil - just one coil or spark output. e.g. single coil, TFI, HEI, EDIS. EDIS actually
has multiple coils, but there is only one output from the MS3-Pro to the EDIS module, so it
uses the “Single Coil” setting.
– Wasted spark - one double ended coil for a pair of cylinders. i.e. 2 spark outputs on a 4
cylinder.
– COP - coil-on-plug - one coil per cylinder fired once per cycle (typically needs a cam sensor)
– Wasted COP - one coil per cylinder fired twice per cycle (typically does not need a cam
sensor.) Coils are wired the same as COP.
– Dual dizzy - for single plug engines with two coils and two distributors, each operating half
the cylinders. This appears on some Lexus, Porsche, Jaguar, and BMW engines.
• Spark hardware in use - Setting this to Spark uses the regular spark outputs, which supply a 5
volt signal. You may select Tach Out to use the tach output to control a CDI ignition or Ford TFI
distributor, which uses a 12 volt square wave.
• Cam input - Normally this should be the CMP input, but you can also use Digital Frequency In
2 for Hall sensors. The MS3-Pro can also use MAP sampling combined with a missing tooth
wheel on single or two cylinder motorcycle engines.
• Tertiary tach input - Only used on Audi tri-tach inputs.
• Flip polarity on hi-res tach - used on Optispark and Nissan distributors to invert the signal on
the ring of 360 slots.
The remaining settings on the left hand side are for Toothed Wheel mode, which will be covered in
the specific ignition settings section. Here is what the settings on the right hand side do.
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• Fixed advance - When set to "Fixed Advance", the spark timing is locked to the value set below.
This is used for confirming timing with a strobe timing light during setup. For normal operation,
this must be set to "Use table" so that the spark advance table is used.
• Use Prediction - Normally set to "1st Deriv Prediction". Alters the way the internal spark timing
calculation functions. With no prediction, spark retard may be observed during engine acceleration. With 1st Deriv, this is automatically compensated for.
• Timing for Fixed Advance - only applies when "Fixed Timing" is set above. Timing is then
locked to this specified value.
• Cranking dwell - specifies the base coil dwell time during cranking before battery correction is
applied.
• Cranking advance - The MS3-Pro uses a fixed timing angle while cranking, specified here.
• Toyota Multiplex - Used for Toyota DLI distributorless ignitions. Known applications include the
7M-GTE and Japanese market 4A-GZE. This uses the primary spark output as a timing signal,
and secondary spark outputs to specify which coil is active.
• Dwell type - Can be "Standard Dwell", "Fixed Duty", "Time after Spark", "Charge at Trigger" to
accommodate different ignition types.
– Standard Dwell - this is the setting to use for most installs. i.e. regular coils that are fired
by a module or with internal drivers or logic-level COPs. This is also used with GM-HEI7
and GM-DIS.
– Fixed Duty - locks the spark output to a constant duty cycle instead of controlling dwell.
This is typically used for ignition modules that control the dwell directly, including Ford’s
"Push Start" TFI modules, Bosch "smart" ignition modules, or MSD and other capacitive
discharge boxes.
– Time After Spark - only intended for Saab Tri-Ionic DI cassettes that require a backwards
dwell signal.
– Charge at trigger - This is a highly specialized mode intended for driving a CDI thyristor
directly. Do not use with multi-tooth wheels. Do not use with direct coil control or COP type
ignitions as the dwell varies with rpm and advance. Do not use if you are not certain what
a thyristor is.
• Use dwell vs rpm curve - For Saab Tri-ionic and time-after-spark, the dwell can be varied with
rpm.
• Use Dwell Table - Enables a 3D table of dwell as a function of RPM and load. This lets you
run a low dwell under vacuum and increase dwell only under boost, to reduce heat load on the
coils.
• Nominal dwell - The base dwell time before battery voltage correction. (With the standard
correction curve, this time is applied at 14V.) Typical values are 3-4 ms.
• Spark duration - The time required for the spark to complete, typically in the order of 1 millisecond. Note that in older single-coil systems with many cylinders, the dwell time can be
constrained at higher rpms as there isn’t enough time between cylinders for the desired dwell
and spark. The dwell time is automatically reduced in this case (this is the reason for stock HEI
ignition being weak above 5000rpm on V8s.) With wasted-spark or COP, there is far greater
time between ignition events and this dwell-reduction rarely occurs.
• Dwell time - the backwards dwell time for Time-After-Spark
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• Dwell duty - for fixed duty, this specifies the percentage duty cycle of the output signal.
• Spark Hardware Latency - all electronic devices take a finite time to propagate signals and
switch. This setting allows for that slight delay. If you notice a slight retarding of ignition timing
with rpm while strobing with fixed timing, you can enter a small number in here to remedy it.
• Middle LED indicator - not used on MS3-Pro.
• Spark Trim - enables the adjustment of timing per individual cylinder. This requires a suitable
trigger wheel capable of cylinder identification; modes like Basic Trigger do not allow this.
Now, for the settings for specific ignition modes. Note that many of the model specific modes are
named after one common application of the settings, but there are often other engines that will use
the same settings. For example, the “4G63” mode is not just used on the Mitsubishi 4G63, but also
on other Mitsubishi engines and Mazda Miatas.
5.3.1 Specific ignitions: Basic Trigger
The distributor is the traditional method of timing spark and distributing the high-tension spark voltage
to individual spark plugs. Originally, this used a set of breaker points, a condenser and a single
ignition coil. Most distributors feature mechanical and vacuum advance systems to match spark timing
somewhere close to optimal for different operating conditions. Later systems were "breakerless" and
replaced the high-maintenance points with VR, hall or optical sensors, but there is still just one tooth
for each cylinder. When combined with OEM fuel injection systems, the distributor may be "locked"
in that there is no advance mechanism and the timing is controlled by the computer. Any engine
predating fuel injection will have the tach pickup within the distributor. With most distributors there is
no cylinder identification so it is not possible to run sequential fuel; Ford Signature PIP TFI distributors,
which used one short vane and the others a different length, are the exception.
This mode also covers arrangements with a single crank wheel with one tooth for every two cylinders, where there is no cam sensor used. This looks exactly the same to the ECU - other than that
the signal is more accurate.
Ford TFI and GM computer controlled are specialized versions of the distributor system and will
be covered in their own sections. “Basic Trigger” does not cover “dual sync” distributors, which have
two pickups and use “Toothed Wheel” mode, or setups which have a distributor but use a more
complicated trigger pattern than the basic “one tooth, one cylinder.” There are covered in their own
sections.
Examples of ignitions that use “Basic Trigger” include:
• Ford TFI
• GM HEI (both original and computer controlled)
• Chrysler Lean Burn
• MSD distributors and Flying Magnet
In all cases, you’d wire the Crankshaft Position In wire to the distributor pick-up, and Spark A Out to
an ignition module.
5.3.1.1 Input phasing In most cases you will be controlling timing with the MegaSquirt, for this
you need a trigger that does not vary angle with rpm or load. This is called a "locked distributor".
Early distributors such as points, original HEI, Duraspark etc, all have advance mechanisms built
in. Similar distributors can be converted for use with MegaSquirt • Remove ignition module (if present)
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• Connect pickup sensor (VR, hall, opto, points) to MegaSquirt.
• Remove and weld up mechanical advance mechanism.
• Remove vacuum canister.
• Use remnants of vacuum advance mechanism to achieve correct input:output phasing. You
may be able to set the rotor output phasing FIRST and then rotate the baseplate to achieve the
correct input phasing.
Later engines may feature a distributor in conjunction with computer controlled timing - usually these
distributor are "locked" from the factory and should already have good input and output phasing. (e.g.
Ford TFI, GM computer controlled, Bosch hall effect.) Align as per the factory manuals and determine
how it is phased before you modify anything!
The crank angle at which the tach input triggers is of importance and needs to be configured in
the MegaSquirt. For best spark control, there are some optimal and some disallowed crank angles. A
typical engine will have an operating advance range of approximately 10-50ř BTDC timing (depending
on engine type.) The trigger must not happen during this range of angles. It can be really helpful to
install timing tape on your crank pulley or temporarily mark on a range of angles.
For best accuracy at high revs or during transients, aim for the trigger to align at 60-90ř BTDC.
This also allows a full range of timing and including retarded timing should you need it for boosted
conditions. This range of trigger angle is preferred for new installs. For slightly better starting, but
not quite such good running accuracy, aim for a trigger ~10ř BTDC or your desired cranking advance.
This is the typical trigger angle for TFI and computer controlled HEI. You cannot retard timing later
than the trigger angle. e.g. 9ř BTDC and lower are not possible with a 10ř BTDC trigger angle.
The VR sensor input presents a simple pulse as the reluctor passes the sensor, this gives a timing
position easily identified by eye. Rotate the engine to 60ř BTDC (or 10ř BTDC if chosen) and then
align the distributor so the reluctor aligns with the center of the sensor.
5.3.1.2 Ford TFI distributors Ford’s TFI module was used throughout the 1980s and into the
1990s on many millions of vehicles in two main mounting positions - “distributor mount” and “remote
mount”. There are also two electrical versions: "Push Start" and "Computer Controlled Dwell" : documentation claims that these can be distinguished by color, but that appears unreliable. Checking
the wiring on pin4 is likely best. The wiring of the modules is largely the same, just the distributor
mount connects directly to a 3 wire hall sensor in the distributor. In most installations you do not need
to concern yourself with that as only the “PIP” and “SPOUT” connections are of interest. The other
connections should be left stock.
The white wire on the CKP input connects to the PIP signal, and the Tach Out wire (NOT Spark A
Out) connects to PIP. Be sure “Spark hardware in use” is set to Tacho.
The module described mainly here is the "Push Start" type that uses a 12V start signal. While
some documentation claims that all “PS” type modules are gray, we’ve seen them in black as well. A
more reliable indicator is that pin 4 will be connected to a 12 volt source when cranking. 50% dwell
duty should be used. On the "CCD" type, pin 4 runs as a diagnostic signal to the original ECU. These
modules need normal dwell control instead of a fixed duty. We recommend starting with 3.0 ms dwell
and adjusting to match the coil used. Other wiring should be the same.
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"Base Timing" on the distributor (with computer control "SPOUT" disconnected) is around 10BTDC.
This is the number you should use as your initial Trigger Offset, and adjust as needed to obtain correct
timing. As these distributors were designed for ECU control, the rotor arm phasing should already be
correct.
The “Signature PIP” versions of the TFI distributor have a shorter vane used to identify the #1
cylinder. These appeared on factory sequential injected engines. These are still set up as basic
trigger, but you will set “TFI Signature PIP” under Ford TFI Options.
Set “Ignition Input Capture” to “Falling Edge” and Spark Output to “Going High”.
5.3.1.3 GM HEI The original "High Energy Ignition" (HEI) distributors used the 4 pin module from
the early 1970s (as shown in the photo at the top of the page.) That module is fine in the breakerless
distributor as designed, but is not suitable for computer timing control. The later 7 and 8 pin modules
and corresponding distributors are designed for computer control and should be an easy swap onto
earlier engines - not only are those modules intended for computer control, but their distributors are
already locked-out so no modifications are required. HEI7/8 uses three control wires to/from the
MS3-Pro.
• The ’Ref’ signal from the module to the MS3-Pro gives rpm and engine position information. It
connects to the white wire on the CKP In line.
• The ’Est’ signal from MS3-Pro to the module controls the advance when running. It connects to
Spark A Out.
• The ’Bypass’ signal from MS3-Pro to the module allows the module to beneficially control its
own advance during cranking. Once the engine has been running for more than 5 seconds, the
MS3-Pro takes control of timing. It connects to Spark B Out.
To enable the bypass, set GM HEI / DIS options to “GM Bypass on SpkB”. Set Ignition Input Capture
to “Rising Edge” and Spark Output to “Going High”. Set trigger angle 10 and adjust as needed.
5.3.2 Specific ignitions: Trigger Return
Trigger Return is a special case of Basic Trigger which can be used if you have a Hall effect distributor
or optical distributor where all the slots, shutters, or vanes are equally sized. The purpose of the
"Trigger Return" mode is to have accurate cranking timing as well as accurate running timing. It
achieves this by using the signal from both edges of a vane/slot. One edge is used for the timing
calculations during running and will typically pass the sensor at 55ř BTDC or more. The other edge
is used for cranking timing and must pass the sensor at the desired cranking advance angle e.g. 10ř
BTDC.
Examples of ignitions that use Trigger Return include:
• Many ’80s era water cooled VWs
• Volvos with Bosch LH2.2 ignition
5.3.3 Specific (non) ignition: Fuel only
When the MS3-Pro is not controlling ignition, you will need to send it a tach signal on the CKP In
white wire. The MS3-Pro cannot trigger off the negative terminal of the coil. Examples of acceptable
signals that you CAN use to trigger the MS3-Pro include:
• Electronic distributor pickups
• The tach output terminal of an MSD or other capacitive discharge ignition box
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5.3.4 Specific ignition: Toothed wheel
The Trigger Wheel mode is designed to support most combinations of regular missing tooth wheels
with or without a cam signal. Other ignition modes are used to support irregular or OEM specific
wheel patterns.
The table below lists all of the valid combinations for trigger wheel. However, some of the modes
will rarely be used. The most common are:
• 36-1 on crank with no cam sensor - many Fords
• 36-1 on crank plus single tooth cam sensor - same
• 60-2 on crank with no cam sensor - many vehicles with early Bosch Motronic engine management: BMW, VW, Audi, Volvo, Vauxhall, Opel, Peugeot etc.
• 60-2 on crank plus single tooth cam sensor - Bosch Motronic systems with sequential injection
or distributorless ignition
• 24 tooth on cam - many Japanese originated vehicles use the Nippon Denso 24 tooth CAS with
differing numbers of 2nd trigger teeth and sensors.
Note - this table is for four-stroke piston engines. Two stroke or rotaries only need 360 degrees of
information for full sequential and COP. Commonly used modes have detailed sections on how to set
them up. Unusual modes are not documented in detail at this time.
For initial setup and determining tooth#1 angle on uncommon setups, having timing marks or tape
on your crank pulley/damper covering the full 360 degrees will be greatly helpful. Speed shops sell
timing tape for a variety of damper diameters. If your engine has no timing marks, you do need to
add them. Just guessing at timing is a great way to damage an engine. Running excessive timing
under load will almost always cause severe engine damage, e.g. broken pistons. It is essential
that timing is confirmed with a timing-light on EVERY install.
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Trigger wheels
Main
Secondary
wheel
wheel
SETTING UP A BASIC CONFIGURATION
Sequential level
Distributor
Semi seFull seonly
quential
quential
Missing
tooth on
crank
None
Y
Y
N
Missing
tooth on
cam
None
Y
Y
Y
Missing
tooth on
crank
Single tooth
on cam
Y
Y
Y
Non
missing
tooth on
crank
Non
missing
tooth on
crank
Non
missing
tooth on
crank
Non
missing
tooth on
cam
Non
missing
tooth on
cam
Single tooth
on crank
Y
Y
N
Settings
Trigger
Main
wheel arwheel
rangement
speed
Single
Crank
wheel with
missing
tooth
Single
Cam
wheel with
missing
tooth
Dual wheel
Crank
with
missing
tooth
Dual wheel
Crank
Single tooth
on cam
Y
Y
Y
Dual wheel
Crank
Cam
Cam wheel
with tooth
per cylinder
Y
N
N
Dual wheel
Crank
Every
Cylinder
Single tooth
on cam
Y
Y
Y
Dual wheel
Cam
Cam
Single tooth
on crank or
two
opposite
teeth on
cam
Cam wheel
with tooth
per cylinder
Y
Y
N
Dual wheel
Cam
Crank
Non
Y
N
N
Dual wheel
Cam
missing
tooth on
cam
Distributor only: Can only use a distributor and batch fire fueling.
Semi-sequential: Supports wasted spark or wasted-COP ignition and semi-sequential fueling.
Full sequential: Supports sequential COP and sequential fueling.
5.3.4.1 Terminology notes
• Missing tooth - This is a regular wheel with a group of "missing" teeth e.g. 12-1, 36-1, 36-2,
60-2
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2nd
trigger
active on
n/a
n/a
n/a
Crank
Every
Cylinder
5.3 Ignition settings
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• on crank - the wheel is rotating at crank speed, normally directly attached to the crank pulley
or flywheel
• on cam - the wheel is rotating at camshaft or distributor speed
• Single coil - a single coil and distributor
• Wasted spark - double ended coils (or a pair of coils) that fire twice per cycle
• Wasted-COP - a single coil per cylinder, but firing twice per cycle. Each coil is controlled by a
separate wire. Useful for testing out a dual wheel arrangement when you are uncertain of the
cam phase.
• COP - a single coil per cylinder that fires once per cycle
• Batch/bank fire - groups of injector fired at once, not timed to a specific cylinder event
• Semi-sequential - injectors fired twice per cycle timed to cylinder events
• Sequential - each injector fires once per engine cycle timed to a specific cylinder event
5.3.4.2 Wheel naming There does not appear to be universal agreement on the way to name
wheels among manufacturers. In the MegaSquirt world, we use a standard where a minus sign
indicates missing teeth, a slash indicates a separate wheel, and a plus indicates a tooth added to the
same wheel. Here are some examples of how this naming convention works.
• 36-1. This means a single wheel with place for 36 teeth and a single tooth omitted. i.e. 35 teeth
at 10 (360/36) degree spacing.
• 36-2. This means a single wheel with place for 36 teeth and a two adjacent tooth omitted. i.e.
34 teeth at 10 (360/36) degree spacing.
• 36-1-1. This means a single wheel with place for 36 teeth and a two non-adjacent single tooth
omitted. This type of wheel is not supported by this generic wheel decoder. It is supported by a
model specific decoder.
• 36-2-2-2. This means a single wheel with place for 36 teeth and a three sets of double missing
teeth. This type of wheel is not supported by this generic wheel decoder. It is supported as
36-2-2-2 with the specific OEM pattern required.
• 24/1. This means 24 teeth (non-missing) on one wheel and a single tooth on a second wheel.
• 36-1/1. This means a one 36-1 wheel and a single tooth on a second wheel.
• 3+1. This means one wheel with 3 equally spaced teeth and an additional tooth to indicate sync.
Not supported by the generic wheel decoder.
5.3.4.3 Specific settings This covers just the settings used in Toothed Wheel mode; settings that
are common to all wheel decoders are covered under “Ignition Settings.”
• Spark Mode - set to "Toothed Wheel"
• Trigger Angle/Offset - always zero in Toothed Wheel mode. You’ll use the Tooth #1 Angle instead.
• Trigger wheel arrangement - see table above for correct settings
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• Trigger wheel teeth - the number of effective teeth, counting the missing teeth as if they existed.
i.e. a 36-1 wheel has 35 physical teeth, but enter 36, as you’re including the teeth that would
populate the gap as well.
• Missing Teeth - the number of missing teeth. Common are 1 for 36-1, or 2 for 60-2 or 36-2
• Tooth #1 angle - definition depends on whether main wheel is missing or non-missing type. See
sections below.
• Main wheel speed - indicates whether the main wheel rotate at crankshaft speed or camshaft
(distributor) speed.
• Second trigger active on - Like ignition input capture above, specifies which voltage level is
considered "active"
• Level for phase 1 - only applies in "Poll level" mode. See Dual+Missing section.
• Check at tooth # - Determines which tooth on the crank trigger is used for polling. See Dual+Missing
section.
• and every rotation of - how often are second trigger input pulses received. See Dual Wheel
section
There are two main categories of install - Existing and Retrofit.
5.3.4.4 Existing In this cases where you are fitting MegaSquirt to an engine already fitted with a
trigger wheel, your main task is to wire up the sensor(s), determine the tooth #1 angle and wire up
your coil(s). It should not normally be necessary to alter the engine.
5.3.4.5 Retrofit If you have an engine that did not originally come equipped with a trigger wheel
(e.g. a distributor based, pre-EFI engine) then you have to mount a wheel and sensor and set the
phasing correctly. For a typical car engine - go for a 36-1 wheel on the crank for non-sequential. or
a 36-1 wheel on the crank and a 50/50 cam tooth with gear-tooth hall sensor for full sequential 60-2
works great on most engines too, but is not advised for very high rpms. For very high revving engines
(such as motorcycle engines) due to the number of teeth per second, 36-1, 24-1 or 12-1 are preferred.
While the code can cope with any sensor/tooth phasing, during cranking the rpms vary up and
down greatly as the engine rotates. It is desirable to place the missing tooth such that it passes the
sensor when the engine is somewhat stable. The OEMs have found that certain tooth #1 angles work
well and it is worth following their lead.
It is suggested to align your wheel and sensor to arrive at the following tooth #1 angles. (See later
for explanation of tooth #1.)
• 4 cylinders ~90-120ř
• 6 cylinders ~50ř
• 8 cylinders ~40ř
Mounting the wheel is quite critical in that it MUST be mounted so it rotates without moving up, down,
left or right, as the sensor needs to see all of the teeth with a gap of 0.75 - 1.0mm. In other words,
keep the runout to a minimum. It is also critical that the bracket is sturdy enough not to vibrate. When
in doubt, make the bracket strong enough that you could lift the engine with it.
Having mounted the wheel and sensor, you can proceed for an existing install.
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5.3.4.6 Missing tooth crank wheel This is a very common configuration for wasted spark with the
most typical wheels being 36-1 (Ford) and 60-2 (Bosch.) Note that the missing teeth are in a single
group - if your wheel has multiple groups then you need a special wheel decoder. We have special
decoders for many of the multiple-gap trigger wheels, such as Chrysler’s NGC or Subaru’s 36-2-2-2
wheels. If you have one of these wheels, see the spark mode sections be
The Megasquirt-3 code benefits from a reasonable number of teeth (hence 36 or 60) for best
ignition timing accuracy. Low tooth count wheels such as 4-1 are not advised.
Make sure you understand the definition we’re using of tooth #1. With the engine rotating in the
normal direction, tooth #1 is the first tooth to pass the sensor after the missing tooth gap.
We use the term "tooth #1" as it is consistent across wheels with one, two, three or four missing
teeth in the group. Once the code knows the tooth #1 angle it automatically calculates other needed
information internally. (If you’ve worked with wheel decoders on some other ECUs, you may have to
specify things like trigger teeth. You don’t need to do that here.)
Clockwise rotation (normal) - method A
Set your engine at TDC, then count the number of gaps to tooth #1 in the direction of rotation
(clockwise here), and multiply by the angular size of the tooth: e.g. 8 teeth * 10ř per tooth = 80ř
• 36-1 wheels are 10ř per tooth (360ř / 36 teeth)
• 60-2 wheels are 6ř per tooth (360ř / 60 teeth)
• 24-2 wheels are 15ř per tooth (360ř / 24 teeth)
Clockwise rotation (normal) - method B
A different way of looking at the same phasing. Turn your engine so that tooth #1 aligns with the
sensor. Read off the tooth#1 angle from timing marks/tape on the crank pulley.
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Critical settings include:
• Spark Mode = Toothed Wheel
• Trigger Angle / Offset = 0
• Trigger wheel arrangement = Single wheel with missing tooth
• Trigger wheel teeth = number of teeth including missing teeth
• Missing teeth = set according to your trigger wheel
• Tooth #1 Angle (deg BTDC) = set as above
• Main wheel speed = Crank wheel
Typical settings:
• Ford 4 cylinder = 36-1, 80ř tooth #1
• Ford 6 cylinder = 36-1, 50ř tooth #1
• Ford 8 cylinder = 36-1, 40ř tooth #1
• Bosch 4 cylinder (Peugeot, Vauxhall) = 60-2, 114ř tooth #1
• Bosch 6 cylinder (many BMWs) = 60-2, 89ř tooth #1
A note about VR sensors and missing tooth wheels If using a variable reluctor type sensor
with a high tooth count (usually 24 or more teeth), missing tooth wheel, you may experience a loss of
sync at high RPM. If this happens, the first thing to try is to put a 10K resistor in parallel with the VR
sensor; this can often improve operation with this particular input.
5.3.4.7 Missing tooth cam wheel This arrangement is not commonly used by OEMs, but does
support full sequential with a single wheel and sensor. Cam triggering is less accurate than crank
triggering due to timing belt or chain stretch.
The Megasquirt-3 code benefits from a reasonable number of teeth (hence 36 or 60) for best
ignition timing accuracy. Low tooth count wheels such as 8-1 are not advised.
The previous section on missing tooth crank wheel generally applies when the wheel is mounted
to the cam, but remember that one rotation of the cam is 720 crank degrees. The settings are in crank
degrees. So a tooth #1 that is 8 gaps earlier than the sensor on a 36-1 wheel would give a 160ř tooth
#1 angle (8 * 10 * 2 [for cam] ) .
Critical settings include:
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• Spark Mode = Toothed Wheel
• Trigger Angle / Offset = 0
• Trigger wheel arrangement = Single wheel with missing tooth
• Trigger wheel teeth = number of teeth including missing teeth
• Missing teeth = set according to your trigger wheel
• Tooth #1 Angle (deg BTDC) = set as above
• Main wheel speed = Cam wheel
5.3.4.8 Missing tooth crank wheel and single tooth cam wheel This is an very common arrangement that supports full sequential and coil on plug. (For 50/50 type polled cam wheels, see the
next sub-section.)
The definition of tooth#1 is the same as the basic missing tooth crank wheel and should be phased
in the same way. Ensure you also read the section above. The cam input tells the code which engine
cycle/phase it is on. From the crank wheel alone, the code knows when cylinder one is at TDC, but it
cannot distinguish TDC compression or TDC exhaust. The cam sensor adds this information, which
is why it needs to be one pulse only per engine cycle.
The cam signal is a single pulse, usually generated by a narrow tooth, vane, or window. Technically, it is edge triggered. For VR type sensors, the edge setting will depend on the wiring you use
(typically Rising) as the signal is a very short pulse. For a hall type sensors you need to ensure that
the edge you choose matches up with the phasing as below. To confirm correct cam sensor phasing
proceed as follows.
First, set your engine at TDC compression #1.
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Now rotate the engine backwards to tooth #1. The angle read off the damper is the tooth#1 angle.
Now rotate the engine backwards some more, at least one or two teeth - this is the best place for
the cam tooth to pass the sensor, if you are retrofitting a trigger setup. However, the cam sensor can
be at any angle except having the active edge aligned in the tooth gap.
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Critical settings include:
• Spark Mode = Toothed Wheel
• Trigger Angle / Offset = 0
• Trigger wheel arrangement = Dual wheel with missing tooth
• Trigger wheel teeth = number of teeth including missing teeth
• Missing teeth = set according to your trigger wheel
• Tooth #1 Angle (deg BTDC) = set as above
• Main wheel speed = Crank wheel
• Second trigger active on = Set as above
The “and every rotation of” setting is grayed out as this mode only allows the second trigger to be on
the cam wheel.
This wheel decoder mode has a limp home feature: If the camshaft position sensor works OK
during startup, but the MS3-Pro subsequently loses the cam wheel, it will “remember” what phase the
cylinders are on, and keep running as if nothing happened.
5.3.4.9 Missing tooth crank wheel and polled (50/50 or half moon) cam wheel This is an fairly
common arrangement that supports full sequential and coil on plug. Here, a missing tooth wheel is
used on the crank in the common way, and a hall-effect or gear tooth sensor is used on the cam with a
long tooth or window or vane. The MS3 first checks for a missing tooth in the crank wheel sensor, then
checks the voltage coming from the cam signal to determine if the cylinder is on the compression or
exhaust stroke, without waiting for the cam sensor to reach an edge. This gives you the ability to have
full sequential, but the engine syncs up as fast as a regular missing tooth crank wheel without the
cam sensor. Different OEM implementations exist - some engines use a 50/50 cam pattern, Vauxhall
red-top engines use a window in the distributor rotor that spans the missing tooth region. As far as
the code is concerned, these are equivalent because it only “looks at” (polls) the cam just after the
missing tooth.
While this code normally checks at the missing teeth, the “Check at Tooth #” setting allows for it
to delay this checking and look for a pulse on a later tooth. By default, this is set to tooth zero for the
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missing tooth. Some engines use multiple teeth on the cam wheel, with one tooth present on one
rotation of the crank but not the next but no cam teeth over the missing tooth on the crank wheel.
In this case, you can set “Check at Tooth #” to a crank tooth that lines up with a cam tooth on one
rotation but not on the next rotation.
The definition of tooth #1 is the same as the basic missing tooth crank wheel and should be
phased in the same way. The cam input tells the code which engine cycle/phase it is on. From
the crank wheel alone the code knows when cylinder one is at TDC, but it cannot distinguish TDC
compression or TDC exhaust. The cam sensor adds this information which is why it needs to be one
"tooth" only per engine cycle.
At close to tooth #1 the code examines the voltage level on the input to determine which phase it
is on - the "tooth" should be normally start at least 20 crank degrees before tooth#1 and continue for
another 20 crank degrees afterwards. (The level is actually polled at tooth#2.)
To confirm correct cam sensor phasing proceed as follows. First, set your engine at TDC compression #1.
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Now rotate the engine backwards to tooth #1. The cam sensor should be roughly in the middle
of window/tooth/vane. With the cam sensor powered and connected to the MegaSquirt, measure the
output voltage. When using the standard cam input, a voltage of ~0V here requires the HIGH setting
and a voltage of ~5V here requires the LOW setting, as the MS3-Pro input conditioner inverts the
signal.
Now rotate the engine backwards a full revolution. The cam sensor will be opposite that previous
window/tooth/vane. (If there was a window before it must be a vane now and vice versa.) You can
use a volt meter to confirm the output has changed its state.
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Example of a distributor converted to a cam sensor, using a commonly available gear-tooth sensor.
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Critical settings include:
• Spark Mode = Toothed Wheel
• Trigger Angle / Offset = 0
• Trigger wheel arrangement = Dual wheel with missing tooth
• Trigger wheel teeth = number of teeth including missing teeth
• Missing teeth = set according to your trigger wheel
• Tooth #1 Angle (deg BTDC) = set as above
• Main wheel speed = Crank wheel
• Second trigger active on = Poll Level
• Level for phase 1 = set as above
• Check at tooth # = which tooth after the missing tooth to use to poll the cam sensor. Leave at 0
to check when the missing tooth is present.
5.3.4.10 Nippon Denso CAS The Nippon Denso CAS (crank angle sensor) comes in a number
of versions, which all appear to use a 24 tooth main wheel and a second wheel with one, two, three
or four teeth. There is a single sensor (called Ne) pointing at the 24 tooth wheel and one (G1) or two
(G1 and G2) sensors pointing at the second wheel. This style of CAS is very common on Toyota and
Mazda engine from the 1980s and 1990s. Honda also used a variant incorporating a 24 tooth, 4 tooth,
and 1 tooth wheel into the distributor. The number of teeth on the second wheel determines whether
it can be used (without modification) for single coil distributor, wasted spark or coil-on-plug (COP) and
sequential. The version with a single tooth and two pickup sensors is intended for sequential. The
two sensors are used by the OEM to allow the engine to synchronize within one engine revolution.
Presently, the MS3-Pro only supports using one of the "G" sensors.
Some Toyota JZ series and Honda H series engines used a variation of this method, with a 12
tooth crank wheel replacing the 24 tooth cam wheel. Other than the greater accuracy of a crank
trigger, this makes little difference from the ECU’s perspective.
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Here are the connections used.
CAS connection
MS3-Pro wire
GND, NE-, or G- CKP- and CMPNE
CKP+
G1 or G2
CMP+
Other G sensor
(not used)
Note that you must connect both the CKP- and CMP- to the ground wire if there is only one
ground. The MS3-Pro’s input circuit uses a differential input, and both circuits must be at the same
reference volts to use this mode.
5.3.4.11 Non-missing tooth cam wheel with single-tooth cam This arrangement is one of the
variants used in Nippon Denso CAS. This also covers the common “dual sync” aftermarket distributors, AEM’s Engine Position Module, and a few other aftermarket distributor or CAS setups.
With the single tooth every 720 degrees this setup gives enough engine information for full sequential fuel and spark.
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Make sure you understand the definition we’re using of tooth #1. With the engine rotating in the
normal direction, tooth #1 is the first tooth to pass the main sensor after the single tooth has
passed the second sensor.
Make sure these do not happen at the same time - in the diagram you can see that the main sensor
is over a gap when the secondary sensor is aligned with its tooth. If they do happen at the same time,
you can probably chose the triggering edges so the MS3-Pro does not “see” the two edges at the
same time. Here is how to set this one up.
First, set your engine at TDC compression #1.
Now rotate the engine backwards until the "cam" sensor and tooth line up. If you rotated more
than one turn, then add 360 to your tooth#1 angle.
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Now rotate the engine forwards until the next "crank" tooth aligns with its sensor. The crank angle
now is the tooth #1 angle. (Note that angles shown in diagram are examples only)
Critical settings include:
• Spark Mode = Toothed Wheel
• Trigger Angle / Offset = 0
• Trigger wheel arrangement = Dual wheel
• Trigger wheel teeth = number of teeth
• Tooth #1 Angle (deg BTDC) = set as above
• Main wheel speed = Cam wheel
• Second trigger active on = Set to make sure this does not overlap with main wheel
• and every rotation of = Cam
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5.3.4.12 Non-missing tooth cam wheel with two opposite teeth on the cam This arrangement
is one of the variants used in Nippon Denso CAS.
With the cam tooth every 360 degrees this setup gives enough engine information for semisequential fuel and wasted spark. (On a rotary such as the RX7, or a two-stroke engine, full sequential
fuel and spark is possible as the engine cycle spans 360 degrees.)
Make sure you understand the definition we’re using of tooth #1. With the engine rotating in the
normal direction, tooth #1 is the first tooth to pass the main sensor after either cam tooth has
passed the second sensor.
Make sure these do not happen at the same time - in the diagram you can see that the main
sensor is over a gap when the secondary sensor is aligned with its tooth. Use the instructions in the
previous single cam tooth section to determine your tooth #1 angle. It will always be between 0 and
360 degrees.
Critical settings include:
• Spark Mode = Toothed Wheel
• Trigger Angle / Offset = 0
• Trigger wheel arrangement = Dual wheel
• Trigger wheel teeth = number of teeth
• Tooth #1 Angle (deg BTDC) = set as above
• Main wheel speed = Cam wheel
• Second trigger active on = Set to make sure this does not overlap with main wheel
• and every rotation of = Crank
5.3.4.13 Non-missing tooth cam wheel with one cam tooth per cylinder This arrangement is
one of the variants used in Nippon Denso CAS. Three and four cylinder versions are known to exist.
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As there is one tooth per cylinder, there is only enough information to run a distributor and untimed
injection. It is not strictly necessary to use both Ne and G wheels. Using both will give you the
improved timing accuracy from the "every-tooth" wheel decoder system, but it is possible to use the
"G" input only and configure as "Basic Trigger" instead. Timing will not be as accurate though.
Make sure you understand the definition we’re using of tooth #1. With the engine rotating in the
normal direction, tooth #1 is the first tooth to pass the main sensor after any cam tooth has
passed the second sensor.
Make sure these do not happen at the same time - in the diagram you can see that the main
sensor is over a gap when the secondary sensor is aligned with its tooth. Use the instructions in the
previous single cam tooth section to determine your tooth#1 angle. It will always be between 0 and
360 degrees.
Critical settings include:
• Spark Mode = Toothed Wheel
• Trigger Angle / Offset = 0
• Trigger wheel arrangement = Dual wheel
• Trigger wheel teeth = number of teeth
• Tooth #1 Angle (deg BTDC) = set as above
• Main wheel speed = Cam wheel
• Second trigger active on = Set to make sure this does not overlap with main wheel
• and every rotation of = Every cylinder
5.3.4.14 Non-missing tooth crank wheel with one cam tooth This arrangement appears on a
few OEM applications, including the Chrysler 318 and 360 Magnum, the Mazda KLDE, and some
Toyota JZ engines. Also, it could be used to extend a simple distributor crank trigger to support sequential. Generally Megasquirt-3 benefits from many crank teeth to improve ignition timing accuracy.
However, with this wheel arrangement, you need to beware of trying to use too many teeth on the
crank as there is a risk of the trigger inputs overlapping as the cam belt or chain stretches. If this
overlap occurs, it will cause sync-loss as the cam tooth moves from being seen "before" to "after" a
crank tooth or vice versa. As a general rule, this mode does not work well with more than 12 teeth on
the crank wheel.
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Make sure you understand the definition we’re using of tooth #1. With the engine rotating in the
normal direction, tooth #1 is the first tooth to pass the main sensor after the cam tooth has
passed the second sensor.
Make sure these do not happen at the same time - in the diagrams below you can see that the main
sensor is over a gap when the secondary sensor is aligned with its tooth. Here’s how to determine
the trigger angles.
First, set your engine at TDC compression #1.
Now rotate the engine backwards until the cam sensor and tooth line up. If you rotated more than
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one turn, then add 360 to your tooth#1 angle.
Now rotate the engine forwards until the next crank tooth aligns with its sensor. The crank angle
now is the tooth#1 angle. (Note that angles shown in diagram are examples only).
Critical settings include:
• Spark Mode = Toothed Wheel
• Trigger Angle / Offset = 0
• Trigger wheel arrangement = Dual wheel
• Trigger wheel teeth = number of teeth
• Tooth #1 Angle (deg BTDC) = set as above
• Main wheel speed = Crank wheel
• Second trigger active on = Set to make sure this does not overlap with main wheel
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• and every rotation of = Cam
5.3.4.15 Other wheel arrangements The examples shown here are not an exhaustive list of all
the combinations that are possible. For other arrangements of crank and cam wheels, you will need
to apply the principles here to your install.
5.3.5 Specific ignitions: EDIS and EDIS Multispark
Ford’s Electronic Distributorless Ignition System (EDIS) is an ignition system that does not require a
cam position signal. It can function with just a variable reluctor (VR) sensor and a 36-1 tooth crank
wheel (36-1 means “36 teeth minus one”, and refers to 36 evenly spaced teeth, one of which has
been removed), it will not work with other pattern wheels or hall sensors.
Because it doesn’t need a camshaft position sensor, EDIS is a particularly easy way to replace
distributor ignitions when retrofitting older engines with a modern computer programmable ignition.
The EDIS modules are very reliable and the system works well. The EDIS module itself handles all the
decoding of the toothed wheel and sends one pulse per cylinder to the MS3-Pro. The code optionally
supports the use of a cam sensor in addition to the EDIS system and then supports sequential fuel.
If your engine already has a different trigger wheel setup, consider using that before retro-fitting
EDIS - many OEM tooth patterns are already supported in MS3-Pro. We generally only recommend
EDIS mode on the MS3-Pro if the engine is already fitted with a complete, working EDIS setup.
The EDIS system is made up of:
• EDIS module
• crank wheel
• crank variable reluctor sensor (VRS)
• and one or more coil pack(s).
Note that in North America, Ford stopped using the external EDIS module in 1996. Cars that do not
have the internal EDIS module can use the Toothed Wheel mode.
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MS3-Pro uses the following wire connections.
Function
Connection
PIP
CKP+
SAW
Spark A out
Cam (if used)
CMP+
Use the following settings:
• Spark mode: EDIS (EDIS Multispark can be used on some 4 cylinder modules, but this function
only works if your module supports it.)
• Trigger angle: 0
• Ignition input capture: Rising edge
• Spark hardware in use: Spark
• Dwell type: Fixed Duty
5.3.5.1 Checking the timing During install, it is important to confirm the timing is correct. To test
this it is best to first run the EDIS in limp home mode. This can be achieved by disconnecting the
SAW plug/socket or switching off/unplugging the ECU. Fit your strobe onto no.1 plug lead as normal
(you may need to try the other tower of the pair). Ensure EDIS still has power and crank your engine,
check that the timing is exactly 10ř. If not, adjust your sensor until it is. It is safe to idle the engine
with the SAW lead disconnected; timing should be rock solid at 10ř BTDC. Don’t forget to reconnect
the plug when done!
Now that you have confirmed that the EDIS is correctly running at 10ř BTDC base timing, you
need to check that MegaSquirt is correctly commanding timing on the EDIS. Start the engine and
then on the Ignition settings menu, select Fixed Timing and enter 15 BTDC; check that you strobe 15ř
BTDC on the crank.
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When done, reset Fixed Advance to “Use table.”
5.3.5.2 Cam sensor and EDIS The EDIS module itself does not need a cam sensor as it always
runs in wasted spark, firing each coil pair every crank revolution. However for sequential fuel it is
necessary to use a cam sensor in addition so the MS3-Pro knows what phase the engine is on. Most
original cam sensors are 2 wire VR type, so only require a ground and the signal connecting to the
MS3-Pro. The code works the same whether a hall or VR sensor is used.
5.3.6 Specific ignitions: 420A/Neon
Known applications include:
• First generation Chrysler / Dodge / Plymouth Neon (both DOHC and SOHC)
• Second generation Diamond Star cars (Mitsubishi Eclipse / Eagle Talon) with 420A
• 2001-2002 Chrysler PT Cruiser
• Many four cylinder “Cloud Cars” (Stratus, Breeze, Cirrus)
This mode uses an irregular crank wheel that can support wasted spark without a cam sensor. It also
allows sequential injection if the cam sensor is used. Both sensors require pull-up resistors from the
sensor power wire to the signal wire. Ignition input capture should be set to Rising Edge.
Factory ignition coils on these motors require an external ignition module such as the QuadSpark.
5.3.7 Specific ignitions: 36-2+2
Known applications include:
• 5.7 and 6.1 Hemi without VVT
• Second generation Neon and SRT-4
• Most other Chryslers from 2003 and later
This mode uses a crank trigger (which Chrysler calls a “tone ring”) with 36 base teeth and two separate gaps 180 degrees apart. The number of teeth on the camshaft position sensor change with the
number of cylinders; the MS3-Pro will select the cam wheel based on the general setup information
entered. The camshaft position sensor must be used if sequential injection or ignition is used, but the
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crank wheel can run the engine in semi-sequential and wasted spark. Both sensors require pull-up
resistors. Ignition input capture should be set to Rising Edge.
Factory ignition coils on these motors require an external ignition module such as the QuadSpark.
VVT Hemi models used a 60-2 wheel that uses Toothed Wheel mode.
5.3.8 Specific ignitions: 36-2-2-2
Known applications include:
• Many Subarus built after 2000
• Mazda RX8
• Mazda MX5 from 2005 and later
This mode uses a VR sensor and a crankshaft trigger wheel with two gaps on one side and one gap
on the other. This mode can support sequential injection if cam input is used. Ignition input capture
will depend on the way the sensor is wired.
5.3.9 Specific ignitions: Subaru 6/7
Known applications include:
• Many Subarus from the 1990s through mid 2000s
This mode uses a 6 tooth crankshaft trigger and a 7 tooth camshaft trigger, both with VR sensors.
You must use both sensors with this spark mode. Sequential injection is supported. Because of the
nature of the VR sensors, it can trigger off either edge, depending on the wiring. Ignition input capture
should be tried both ways and set to which one gives you the most stable signal.
5.3.10 Specific ignitions: Miata 99-05
Known applications include:
• Mazda MX5 Miata from 1999 to 2005
This mode requires using both cam and crankshaft position sensors. This code allows for both sequential injection and control of the variable valve timing found on 2001-2005 engines. Ignition input
capture should be set to Rising Edge.
5.3.11 Specific ignitions: 6G72
Known applications include:
• Mitsubishi 3000GT
• Mitsubishi Galant V6
• Some other Mitsubishi and Chrysler V6 models
This spark mode comes in two variations. One used an optical trigger with six slots for the CKP signal
and four slots for the CMP signal. Another variation used Hall effect sensors with a three tooth crank
trigger and a four tooth cam trigger. Both require pull-up resistors, and from the ECU’s perspective,
they look alike, as in both cases the ECU will “see” three pulses on the CKP wire for every crank
revolution.
Ignition input capture needs to be set to Rising Edge. This mode supports full sequential operation.
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5.3.12 Specific ignitions: IAW Weber
Known applications include:
• Ford Sierra Cosworth
• Some Fiat and Lancia applications
This application uses a four tooth crank trigger with a VR sensor and a two tooth cam trigger with
a Hall effect or VR sensor, depending on the year. Ignition input capture needs to be set to Falling
Edge. This mode supports full sequential operation.
5.3.13 Specific ignitions: CAS 4/1
Known applications include:
• Mitsubishi 4G91
• Mazda Protege and 323 with optical distributor
This mode uses a Hall effect or optical sensor spinning at cam speed, with both sensors requiring
a pull up. There are four teeth on the CKP signal and one on the CMP signal. You will need to set
the “Angle between main and return” parameter to the distance between edges of the optical sensor.
Note that if you are not able to get a stable signal off both edges, you should instead use Toothed
Wheel mode. Full sequential operation is supported.
5.3.14 Specific ignitions: 4G63
Known applications include:
• Mitsubishi 4G63 with distributorless ignition, as used in Eclipse, Galant VR4, and Lancer Evolution
• 1990-1997 Mazda MX5 Miata
This spark mode comes in several variations. One used an optical trigger or Hall effect sensor with
four slots for the CKP signal and two unequal length slots for the CMP signal. Another variation used
Hall effect sensors with a two tooth crank trigger and a two tooth cam trigger. All require pull-up
resistors, and from the ECU’s perspective, they look alike, as in both cases the ECU will “see” two
pulses on the CKP wire for every crank revolution.
Ignition input capture needs to be set to Rising Edge. This mode supports full sequential operation.
5.3.15 Specific ignitions: Twin trigger
Twin trigger is a specific ignition mode designed for use on a range of motorbike engines that use
a crank or cam mounted reluctor and two discrete pickup sensors. Each sensor triggers a separate
ignition coil.
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Supported combinations include:
• Crank wheel. 4 cylinder, 4 stroke engines with wasted spark ignition, non sequential fuel.
• Crank wheel. 2 cylinder, 4 stroke engines with in wasted spark ignition, non sequential fuel.
• Cam wheel. 2 cylinder, 4 stroke engines with in coil-on-plug ignition, non sequential fuel.
This mode can be used on both even fire and odd fire engines.
5.3.16 Specific ignitions: Chrysler 2.2 / 2.5
This setup is unique to Chrysler 2.2 and 2.5 engines from the 1980s and early 1990s, equipped with
multiport injection. (The TBI versions of this engine used Basic Trigger mode instead.) It uses a four
tooth cam trigger with a “window” in the middle of one tooth, Hall effect sensors which require pull
up resistors, and both sensors read the same trigger wheel, but from different angles. Currently this
mode is experimental. With current (1.3.3 and later) firmware, only the primary Hall effect sensor is
used, wired to CKP+.
5.3.17 Specific ignitions: Renix 44-2-2
Known applications include:
• 1987-1990 Jeep Cherokee 4.0
• Many 1980s era Renault products
This trigger mode came in a four cylinder variation which used 44 base teeth with two gaps 180
degrees apart, and a six cylinder version with 66 base teeth and three gaps 120 degrees apart. A
cam signal is needed for sequential injection. Jeeps had a cam sensor from the factory, while most
Renaults did not.
5.3.18 Specific ignitions: Suzuki Swift
This mode is considered experimental. It works for Suzuki Swift engines with a distributor with a VR
sensor and 12 irregularly spaced teeth. This mode does not support sequential injection, and can
only be used with a single coil. Because of the nature of the VR sensor, it can trigger off either edge,
depending on the wiring. Ignition input capture should be tried both ways and set to which one gives
you the most stable signal.
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5.3.19 Specific ignitions: Suzuki Vitara 2.0
This mode is considered experimental. It works for a later modification of Suzuki’s irregularly spaced
teeth that has 11 teeth instead of 12. Supports sequential injection. Because of the nature of the VR
sensor, it can trigger off either edge, depending on the wiring. Ignition input capture should be tried
both ways and set to which one gives you the most stable signal.
5.3.20 Specific ignitions: Daihatsu 3cyl
This mode is considered experimental. The Daihatsu three cylinder version has 3 equally spaced
teeth in a distributor with a fourth tooth adjacent to one of the teeth and a VR sensor. Supports
sequential injection.
5.3.21 Specific ignitions: Daihatsu 4cyl
This mode is considered experimental. The Daihatsu four cylinder version has 4 equally spaced teeth
in a distributor with a fifth tooth adjacent to one of the teeth and a VR sensor. Supports sequential
injection.
5.3.22 Specific ignitions: VTR1000
This ignition appears on some Honda V-twin motorcycles. It uses a 12-3 crank trigger with a VR
sensor and no cam sensor. Sequential injection is not supported.
5.3.23 Specific ignitions: Rover #1
This mode is used on Rover K-series engines with a crank trigger wheel with 36 base teeth and two
one tooth gaps, 180 degrees apart. This only allows a single coil and batch fire injection. Cam input
is not supported.
5.3.24 Specific ignitions: Rover #2
This mode is used on Rover K-series engines with a crank trigger wheel with 36 base teeth and four
one tooth gaps. This only allows a single coil or wasted spark ignition and batch fire or semi-sequential
injection. Cam input is not supported.
5.3.25 Specific ignitions: Rover #3
Similar to Rover #2, but the gaps are two teeth wide and positioned differently. As with Rover #2,
supports wasted spark and semi-sequential injection, but does not support cam input.
5.3.26 Specific ignitions: GM 7X
This appears on several GM four and six cylinder engines with distributorless ignitions. GM refers to
the crank wheel in their internal documentation as a 7X trigger wheel. It has six equally spaced teeth
and a seventh tooth for cylinder identification. Cam input is supported for sequential injection.
5.3.27 Specific ignitions: QR25DE
Used on the Nissan QR25DE and some other Nissan four cylinders. Supports fully sequential injection.
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5.3.28 Specific ignitions: Honda RC51
Known applications include:
• Honda RC51 and many CBR variants
• AP1 Honda S2000
This one uses a 12 tooth crank trigger and 3 tooth cam trigger, with VR sensors on both. Supports
fully sequential injection.
5.3.29 Specific ignitions: Fiat 1.8 16V
Uses a six tooth crank trigger and a three tooth cam trigger, with a VR crank trigger and Hall effect
cam signal. Both wheels have irregular spacing.
5.3.30 Specific ignitions: Optispark
Known applications include:
• Chevrolet LT1 variations
• Nissan VH45 V8
The Optispark system was used on GM vehicles from 1993 to 1997 on LT1, LT4 and L99 applications.
Internally, it uses a Mitsubishi / Nissan derived optical trigger arrangement. There is a "hi-res" track
of 360 slits and a "low-res" track of 8 slots of varying length. The pickup design is sound, but the
high-tension side can be problematic with the "correct-a-cap" design - especially if a high energy
aftermarket ignition system is used.
The Megasquirt-3 Optispark decoder uses both low and high resolution tracks for improved ignition
accuracy. (Most other aftermarket implementation only use the low resolution track.) The system
allows for sequential fuel and the single coil as per the original install. However, as an enhancement,
the single coil can be replaced by a wasted-spark or coil-on-plug setup to eliminate the troublesome
high-tension cap. This lets you keep the stock Optispark trigger wheel with alternate ignitions.
The Optispark requires a fused 12V supply. This can be tapped into the same 12V supply as the
MegaSquirt. The Ground connection should be run to the sensor ground at the MegaSquirt. The
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high and low resolution tach signals each require a 5 volt "pull up" resistor to operate correctly. The
connector is marked with letters that can be used to identify the functions.
Optispark pin
Function
Connection
A
Low resolution signal
CKP+
B
High resolution signal Digital frequency in 2
C
12 volt power
Shares power
D
Ground
Sensor ground
The low resolution signal runs to CKP. Because of the high frequency of the high resolution signal,
it needs to be connected to the Digital Frequency In or Digital Frequency In 2 input instead of the
CMP signal. You will need to specify which frequency input is used in the Ignition Options / Wheel
Decoder menu. Ignition input capture needs to be set to Falling Edge, and the Spark Output needs to
be set to Going High if using the stock ignition module.
5.3.31 Specific ignitions: Nissan SR20
This mode is used for the RWD version of the SR20DET with coil on plug ignition. These engines
use an optical CAS with four unequally sized slots and a row of 360 slots. It wires up exactly like the
Optispark and uses the same settings.
5.3.32 Specific ignitions: Nissan RB25
Known applications include:
• Nissan Skyline RB25DET, RB26DETT, RB20DET
• Nissan VG30DE and VG30DETT
This mode works for Nissan engines that used six unequally sized slots; it does not work for earlier
VG30E applications which used a distributor and one long slot with five short ones. It wires up exactly
like the Optispark and uses the same settings.
5.3.33 Specific ignitions: LS1
This mode is used on the Chevrolet LS1 and related LSx V8 engines with the 24X wheel. The CKP
input wires to the 24X sensor and the CMP input wires to the 1X sensor. Both are Hall effect sensors,
but do not require pull ups. This spark mode looks like it might be the “dual wheel” mode, but if you
look closely at the crank trigger, you’ll see that the edges of the crank wheel are different lengths.
The MS3-Pro can use these different lengths to sync faster and avoid the sorts of problems caused
by timing chain stretch causing the cam sensor to trigger on different teeth.
Ignition Input Capture needs to be set to Rising Edge for MS3-Pro, and spark output needs to be
set to Going High.
LS2 and other engines with 58X crank trigger do not use LS1 mode, and have a 5 volt crank
sensor. They can use Toothed Wheel mode and the following settings:
• Ignition input capture: Rising edge
• Spark output: Going high / inverted
• Number of coils: Coil on plug
• Trigger wheel arrangement: Dual wheel with missing teeth
• Trigger wheel teeth: 60
• Missing teeth: 2
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• Tooth #1 angle: 15 (note: This needs to be confirmed with a timing light and adjusted as necessary)
• Main wheel speed: Crank wheel
• Second trigger active on: Poll level
• Level for Phase 1: Low
5.3.34 Specific ignitions: YZF1000
This is used on Yamaha motorcycle engines with 7 small holes and 1 long recess in the crank trigger.
There is no cam sensor in this mode, so current firmware only supports wasted spark and semisequential fuel. Known applications include the following Yamahas:
• YZF1000 / Thunderace
• FZR1000
• FZR750
• FZ700
5.3.35 Specific ignitions: Honda Acura (V6)
This mode uses a crank trigger with 24 base teeth and two separate missing teeth, along with a cam
sensor. This is used on many Honda and Acura J series V6 motors.
5.3.36 Specific ignitions: VQ35DE
Used on the Nissan 350Z and other VQ35DE applications. Supports fully sequential operation.
Note that the VQ30DE used in late ’90s Maximas has a different trigger pattern that is not currently
supported.
5.3.37 Specific ignitions: Jeep 2000
Known applications include:
• 1991-2000 Jeep 4.0 inline six
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• Dodge Avenger 2.5 V6
• Some Chrysler minivan V6s
This mode has thee sets of four notches on the crank trigger and a one tooth distributor trigger.
Supports fully sequential operation.
5.3.38 Specific ignitions: Jeep 2002
This mode appears on the last run of the Jeep 4.0 inline six, with coil packs instead of the distributor.
Also appears on the 3.7 V6. Uses the same crank trigger as the Jeep 2000 mode, but with a more
complex cam pattern. This mode is considered experimental.
5.3.39 Specific ignitions: Zetec VTC
Used on Ford Zetec and other four cylinder engines with variable valve timing. It also supports Jaguar
V8s with variable valve timing. Features a 36-1 crank trigger like many other Fords, but a five tooth
cam wheel instead of a one tooth. Uses VR sensors on both, and supports full sequential operation
and variable valve timing. Because of the nature of the VR sensor, it can trigger off either edge,
depending on the wiring. Ignition input capture should be tried both ways and set to which one gives
you the most stable signal.
5.3.40 Specific ignitions: Flywheel tri-tach
Known applications include:
• Early 1980s Porsche 911
• Porsche 944 Turbo (951)
• 1986 and earlier BMW 325e
• E30 chassis BMW M3 with S14 motor
• Many 1980s and early 1990s Audis
This application uses a VR sensor that counts flywheel teeth, with a second flywheel sensor that
reads a single post and, in most implementations, a cam sensor. Note that the number of teeth is
hard coded for a specific number of cylinders. With a cam sensor, this will support full sequential.
Current ones available include:
Number of teeth Number of cylinders
135
5
135
6
136
8
132
4
130
4
For wiring, connect the CKP wires to the flywheel tooth sensor, the reference (1 tooth) flywheel
sensor to the “cam” input, and the cam sensor to the pin selected as tertiary tach input. For most
applications, the flywheel sensors are both VR type with a Hall effect cam sensor, so you will use
CMP for the reference sensor and Digital Frequency In 2 for the cam sensor.
This mode is also considered experimental at this point.
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5.3.41 Specific ignitions: 2JZ VVTi
Used on the Lexus IS300 and many 2000 and later Toyota six cylinder engines with VVTi. This uses a
36-2 crank trigger and a three tooth cam trigger, with VR sensors. Supports sequential injection and
variable valve timing. Because of the nature of the VR sensor, it can trigger off either edge, depending
on the wiring. Ignition input capture should be tried both ways and set to which one gives you the
most stable signal.
5.3.42 Specific ignitions: Honda TSX / D17
Uses a 12 tooth crank sensor with one tooth added for a total of 13 real teeth, combined with a cam
sensor. This allowed Honda to add continuously variable valve timing. Uses VR sensors.
5.3.43 Specific ignitions: Viper V10
Used for Vipers and V10 Rams with JTEC ECU. This one has a crank trigger with five groups of two
teeth. A cam sensor is also required, with a one tooth trigger wheel. Both are Hall effect and require
pull ups. Supports sequential injection, but as the MS3-Pro has only eight ignition outputs, you will
need to run wasted spark ignition. Factory Chrysler coils require external ignition modules such as
the QuadSpark. Gen 1 mode is used for the 1995 and earlier, which had three teeth on the cam
trigger, while the others use regular Viper V10 mode and have a one tooth cam trigger.
5.3.44 Specific ignition: Honda K24A2
This mode uses the same pattern as the TSX / D17 mode but with a different position for the added
tooth on the crank pulley.
5.3.45 Specific ignition: HD32-2
Used for Harley-Davidson engines that use a 32-2 crank wheel and a MAP sensor instead of a cam
sensor. Cam sensor needs to be set to MAP. The front cylinder is considered the #1 cylinder.
5.3.46 Specific ignition: Miata 36-2
This mode is specifically written for ’99-’05 Mazda Miatas running the Flyin’ Miata crank trigger and
the stock ’99-’05 cam sensor. Supports full sequential ignition and VVT. Ignition input capture needs
to be set to Rising Edge.
5.4 Idle valves
The idle valve can be selected under Startup / Idle and chose Idle Control. The first option allows
you to select your type of idle valve:
• None - The engine can run without an idle control valve if the throttle is adjusted to prevent
stalling.
• On / Off Valve - A solenoid that only opens and closes for a very basic open loop operation.
• PWM valve (2 or 3 wire) - Uses a pulse width modulated solenoid where changing the duty
cycle changes the valve position. 2 wire valves use a single solenoid and a return spring, while
3 wire valves use two solenoids in a push-pull configuration. Common applications include Ford,
Mazda, Honda, some Toyotas, and most European cars that do not use drive by wire.
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• Stepper valve (4 or 6 wire) - These valves use four separate coils to rotate a shaft, and have
from 4 to 5 wires. Often used in GM, Chrysler, Mitsubishi, and Toyota vehicles.
The next box allows you to chose between open loop and closed loop.
• Open loop (warmup) - The valve opening amount is set as a function of coolant temperature,
starting at an open value with the engine cold and closing the valve as it warms up.
• Closed loop - The ECU moves the valve as needed to target a specified idle speed.
We recommend only selecting a closed loop idle mode after getting the engine running well in an
open loop mode. Open loop commands how to open the valve as a function of temperature, while
closed loop targets a specific idle speed.
Once you have selected a mode, you will need to set up the individual IAC modes. Settings not
used are grayed out.
5.4.1 On / Off settings
• Fast Idle Temperature - the solenoid opens below this temperature and closes above it.
• Hysteresis - If the temperature drops below the opening temperature, it needs to drop by this
additional amount before re-opening the valve. This prevents the valve from rapidly flickering on
and off if the temperature is almost exactly at the opening temperature.
• Output port - Select which output you wish to use to control the solenoid.
5.4.2 Stepper valve settings
• Time Step Size - This is the number of milliseconds the firmware will wait between each step.
If a valve does not move reliably, this setting should be increased.
– If the valve is perfectly dialed in, this will match the time it takes the coil move the motor
through a single step. If this value is too low, the step is not completed, and the valve does
not move. If the step is too high, the valve will move more slowly than it can - but it will still
work, so it is better to set this too high than too low. Your best bet is to set this for 10 ms,
then decrease until the valve no longer moves. Then add 0.5 to 1.0 ms.
• Initial Time Step Size - When moving more than one step, using a larger time for the first step
can help overcome stiction in the valve. Setting this larger than the Time Step Size can improve
reliability.
• Minimum # of steps to move - This is the minimum number of steps the controlling piece of
code has to command before the code that moves the valve will actually try to move the valve.
We’ve found some stepper valves, particularly used ones on older cars, may stick if commanded
to move fewer than 5 to 8 steps.
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• Homing Steps - This is the number of steps the valve will move (in the closing direction) on
power on so that the rest of the code can rely on the start position being accurate. After retracting to the Start Value, the IAC valve will then move to the number specified in the Cranking
Steps.
• Homing Direction - Specifies if the valve opens or closes during the homing time.
• Wide Open Steps - If the valve is set to home in the opening direction, this sets the number of
steps between closed and wide open. The number of homing steps should be larger than this
to ensure reliable operation. Not used if the homing direction is set to closed.
• Crank-to-Run Taper Time - This is the amount of time the IAC valve uses to transition after
starting from its crank position to its running position. Not used in closed loop control.
• Power Between Steps - Determines what to do when the valve is not moving.
– Moving only: Turns off current to the idle valve. This can reduce current consumption and
make the valve run cooler, but can result in unreliable operation for some valves. Usually
this should only be used for valves that do not freewheel if you try spinning the pintle by
hand.
– Hold current: Applies a reduced current to keep the valve in place. Something of an
intermediate position between the other two options.
– Always on: Applies full power to the last coil to move to prevent the valve from turning.
This can make the valve run hotter but locks the valve in position. Should be used with any
valve that spins freely if you attempt to turn it by hand.
The amount to move the valve is specified in additional menus. Also, see section 6.1.1.3, Idle Valve
Testing, for troubleshooting common problems with a stepper IAC valve.
5.4.3 PWM idle valve settings
• Crank-to-Run Taper Time - This is the amount of time the IAC valve uses to transition after
starting from its crank position to its running position.
• Valve Mode - Normal mode is off at 0% duty cycle, inverted mode is off at 100% duty cycle. As
the name implies, most valves use normal mode. If you’ve found you accidentally wired up a 3
wire IAC valve backwards, just flip this setting.
• Output Port - Allows you to pick which output wires are used. In 3 wire mode, this is for the coil
that opens the valve.
• 3 wire mode - Used with 3 wire rotary IAC valves, common in Denso and Bosch applications.
Set to Off for a 2 wire valve. For a 3 wire valve, this specifies the connection used for the coil
that closes the valves.
• Valve Frequency Selection - Select a frequency from the list. Different valves operate best on
different frequencies.
The PWM idle control uses two additional menus, PWM Idle Cranking Duty and Idle PWM Duty
Table. These specify the IAC position in cranking and running as a function of temperature. A third
menu, PWM Idle Voltage Compensation, lets you specify an amount of duty cycle to be added to or
subtracted from the duty cycle as a function of battery voltage.
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5.5 Sensor calibration
The MS3-Pro uses internal calibration tables to convert the resistance/voltage from the input sensors
into a real world number. It is necessary to setup this calibration so the inputs read correctly. The
built-in calibrations for coolant temperature (CLT) and air temperature (MAT) are for GM sensors, so if
you have GM sensors you are safe to leave these alone. All installs should set the calibration for the
AFR (air fuel ratio) table that is used for the oxygen sensor (lambda sensor) whether narrowband or
wideband. Here’s how to change the sensor calibrations.
1. Unlock the calibrations (This lock/unlock is to ensure the calibration isn’t changed by accident.)
2. Open the Set Thermistor Tables dialogue, then set the CLT calibration (if needed) Pick the
sensor type. The bias resistor value is hardwired at 2490. For a custom sensor, enter three
measured temperature and resistance pairs. (Don’t guess, measure.) For greatest accuracy
the bias resistor should be close to the sensor resistance at a "warm" temperature. Write to
controller.
3. Set the MAT calibration in the same way (if needed.) The bias resistor is 2490 ohms. Write to
controller. Close the dialogue.
4. Calibrate the AFR table. Either pick a preset or look up the voltage/AFR pairs from your controller manual. Write to controller. Note! You should also set your Project Properties for narrowband/wideband and configure the settings on the “EGO control” page.
5. Re-lock the calibrations and Burn.
6. Calibrate TPS. With the throttle closed, "Get Current" on the closed throttle. Then fully open the
throttle and "Get Current" on the open throttle. Close.
7. Calibrate the MAP/Baro. Typically chose from one of the preset values.
8. It is not usually needed to calibrate the battery voltage. Do not alter these values from the
defaults unless you have confirmed the actual voltage reading is inaccurate.
You’ll also want to set up a couple basics on how the MS3-Pro uses the oxygen sensor. Go to Fuel
Settings and select AFR / EGO Control. This will bring up the screen below.
At this point, you’ll just want to set up a couple basic parameters. When first tuning, it helps to
have the O2 sensor correction off, so you’ll set Algorithm to “No Correction”. At the top of the middle
column, specify if you have a wide band or narrow band sensor, and enter your number of sensors
(note that setting the EGO sensor type to Disabled will not just disable correction; it will disable all
O2 input logging as well). The MS3-Pro can read up to four sensors over its analog inputs, and even
more over the CAN bus with appropriate expansion modules.
If you have more than one O2 sensor, you will need to set what port (input) is being used. Select
which analog input is associated with what sensor with the drop down boxes in the middle. The tab at
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the far right lets you pair each injector channel with a specific O2 sensor. The MS3-Pro can use any
O2 sensor to correct for any injector channel.
Once you’re done calibrating the sensors, check them from the main dash. To change any gauges
Right-Click on them and pick a different gauge. The ones we need here are under the Sensor Inputs
categories. Check each of the following with the key on and engine off:
• Coolant temp - is it reasonable?
• Manifold air temp - is it reasonable and within a few degrees of CLT (for a cold engine)?
• Throttle - is it close to 0% with no throttle and close to 100% with full throttle
• Fuel load - if you are running speed density, this should be close to 100kPa at sea level, down
to say 80kPa at high elevations.
• Air:Fuel ratio - this won’t read anything sensible with the engine off.
• Engine speed - should be zero. (Note! If RPM ever reads anything like 65000rpm it means YOU
have made an error in your configuration settings. Normally this will appear as an error when
you first connect. In the unlikely case that it does not, open up Communications, MiniTerminal
and turn the MegaSquirt off then back on again. You’ll get a message explaining what is wrong.
Close MiniTerminal and fix the faulty settings. Then turn the MegaSquirt off then back on again.)
• Fuel pump - the fuel pump output on the MegaSquirt is ground switching for a relay. When the
MegaSquirt is first turned on it will run for a couple of seconds. As soon as tach input pulses
are seen the pump will turn on again. If the engine stalls, the pump is turned off.
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6 Tuning the MS3-Pro
6.1 Getting started
OK, now that you have set up the basics of your tune file, it’s time to make sure everything works and
try to start the motor. First, make sure the ignition coils or ignition module do not get hot with the key
on, ignition powered up, and the engine not running. If the ignition components get hot, turn them off
immediately. You probably have the spark output setting backwards. Try switching this setting, click
Burn, and turn the ECU off and back on again. Confirm that the problem is fixed.
6.1.1 Using output test mode
First, we’ll use Output Test Mode (select it under the CAN bus / Test Modes menu) to check the
outputs. The test mode allows direct control of the coils and injectors. We’ll cover its full use here,
although some of the settings won’t be used until the engine is up and running. Used by accident,
this could cause flooding of the engine and potential damage. Test mode should NOT be used on
a running engine.
The Enable Test Mode button is locked out unless the RPM reading is zero. Click this button to
enable test mode, and when you are done, click the Disable Test Mode to go back to normal operation.
6.1.1.1 Injector test mode The injector test mode can be used both to confirm the injectors are
wired correctly and to use the MS3-Pro as a controller for an injector test bench. If your injectors are
fitted to the engine, you must not run the test mode with fuel pressure or you will fill your engine with
fuel! Remove the fuse from your fuel pump and de-pressurize the line first. To enable injector testing:
• Select Injectors in the Test mode drop down.
• Choose your pulsewidth time in milliseconds. (To just make them click for this test, 3 to 5 ms is
fine.)
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• Choose which injector to test.
• Set Injector testing mode to One.
• If your injectors are powered via the fuel pump relay as is recommended, set the fuel pump to
On.
• For functional testing, set the total number of injections to 65535 (the maximum) or for flow
testing use your chosen number. (When performing repeated tests at the same number, you
need to enter 0, TAB out, then enter the number you want and TAB out again.)
The injector testing mode called Sequence runs the injector in sequence up to the chosen injector.
So if you have six injectors and selected Injector D and Sequence, then the test mode will repeatedly
fire Injector A, then Injector B, then Injector C, then Injector D in turn, but will not fire injectors E and
F. Set the chosen injector to the last one, and you can use this to confirm the injectors are following
the right firing order.
The Output Interval determines how long to go between each test firing of the injectors. If you
want the injectors to fire every 100 ms, you would enter 100. The screen shows the rpm this approximates to in full sequential.
Testing the fuel pump is straightforward; just buttons under Fuel Pump to turn it off and on. You will
notice that "Ready" lights up on the TunerStudio dash when the fuel pump is enabled. If you get no
activity, try starting again. However, if Ready lights up but the pump doesn’t run, you need to check
you fuel pump relay and pump wiring. If this is a new fuel system, make sure that the fuel system
doesn’t leak and that it holds pressure. Note that some aftermarket fuel pressure regulators, including
most from Aeromotive, will hold pressure for only about 30 seconds or so after shutdown even if the
fuel system has no leaks. Most OEM fuel pressure regulators will hold pressure much longer.
6.1.1.2 Coil test mode The coil test mode is useful to confirm you have the coils wired correctly
and to check dwell settings. (Do be careful as ignition coils put out a potential lethal voltage. Typically
30,000V or more.) To enable coil testing:
• Select coils in the Test mode drop down.
• Choose your dwell time in milliseconds. Start low. e.g. 2.0ms.
• Choose which coil to test
• Set Coil testing mode to One
• If your coils are powered via the fuel pump relay as is recommended, set the fuel pump to On.
The Sequence mode and Output Interval work the same for coils as for the injectors. For example, a
4 cylinder wasted spark engine at 6000rpm will fire a coil every 5ms, so each coil is fired every 10ms.
Note that the test mode does not allow dwell periods to overlap in the sequence mode, unlike normal
operation where the dwell periods overlap as required. (This is why traditional V8 distributor spark
was weak at high revs - there was not enough time to charge the single coil between sparks.)
6.1.1.3 Idle valve testing The idle valve has a separate test mode, also under the CAN bus /
Testmodes menu. The idle valve test mode can be used with the engine running or stationary, unlike
the regular Output Test Mode. Note that with a PWM idle valve or a five or six wire stepper valve, you
may need to run a temporary fused 12V supply to the valve if you normally take power from the fuel
pump relay and are testing with the engine off.
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• Idle Valve Homing Steps - This only applies to stepper idle valves. This setting determines how
many steps the motor should move during homing to ensure it has reached the home position.
The number needs to be large enough to close the valve from any unknown starting position.
(This is because there is no position feedback on most automotive stepper IAC valves.)
• Idle Valve Step - the desired valve position if using a stepper IAC valve. Larger numbers should
give a more open valve and higher rpm.
• PWM idle duty% - the desired valve position if using a PWM IAC valve. Larger numbers should
give a more open valve and higher rpm.
(Note that some Bosch rotary PWM valves valves feature a failsafe mode so that zero flow is at a
midpoint, such as 20% duty,; above that the valve operates as expected where more duty gives more
airflow. Below this specific point is a failsafe mode that allows airflow even if there is no control signal.
This is readily observed during test mode.)
There are three control buttons:
• Enable Test - Home Position - for stepper idle valves, this moves the valve through the number
of homing steps back to the home position. (If it doesn’t get all the way back to the stop, increase
the number of homing steps.) The valve will move to the run position shortly afterwards.
• Enable Test - Run Position - enable test mode where the steps or duty setting controls the
valve position
• Enable Test - In/Out Cycle - Cycles the valve continuously between the homing and run positions.
• Stop Testing - disable test mode and allow normal idle control to operate.
Testing a stepper IAC valve First, click the Enable Test - Home Position button, and verify that
the valve closes completely. The valve will move back to the run position on its own; if you are doing
this test yourself and want to make sure the valve is closed, set the run position to zero. Stepper
valves can be a bit more complicated to troubleshoot than PWM valves. Here are some common
problems and what to do if you encounter them.
• Problem: Valve vibrates when commanded to move, but does not actually turn.
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– One coil is wired backwards; swap wire 1A for 1B, or 2A for 2B.
• Problem: Valve moves, but in opposite direction of intended.
– Both coils are wired backwards for the way your tune is configured. With the current
firmware, you can simply change the homing direction in the software. 1.2.4 and earlier code does not allow this. If you encounter this problem on older firmware, you can
reverse the wiring. Switch wires 1A for 1B, and 2A for 2B.
• Problem: Valve does not move at all on initial power up.
– One possibility is incorrect wiring. Make sure 1A and 1B are on one coil, and 2A and 2B
are on the opposite coil.
– The other usual problem is the time step size is set too small. Try increasing it and see if
the valve moves.
• Problem: Idle speed is not consistent from one start to another at the same temperature.
– Usually, this is caused by the homing steps being set too low. Increase this value until the
valve retracts fully.
– If the valve sometimes retracts fully, but not always, this may mean the steps are small
enough that they do not always successfully move the motor. Try increasing the time step
size.
• Problem: The valve retracts normally, but then appears to stop working at some point during
operation.
– Try increasing the time step size and/or minimum number of steps to move. Some older
valves can have problems with stiction. Increasing the time step size will send a longer
pulse, while increasing the minimum number of steps to move will send more pulses that
can un-stick a stubborn valve.
• Problem: Idle speed hunts while the number of steps displayed is constant.
– It’s easy to assume the IAC valve is responsible here. After all, it’s supposed to control the
idle speed, and the idle speed is behaving wrong. However, this is likely to be an issue
with the ignition timing or fueling instead.
Testing a PWM IAC valve PWM valves do not need a homing routine, as the PWM output
directly controls their position. As noted above, be sure your valve has power when testing. The
"PWM idle duty" box allows entry of 0-100% duty output. This could be used to confirm operation of
the valve as well as determining what duty cycle gives what RPM with the engine running.
6.1.2 Checking RPM
Next, we’ll disconnect the injectors and check to be sure the RPM input is working and your timing
is correct. Pull the fuses to the injectors, or disconnect the connectors on the injectors, and crank
the engine. With TunerStudio connected and running, turn the key on and crank the engine. If all
is well you see "Synced" and a stable engine speed (rpm) number. If the pattern is noisy, incorrect
or missing you might see "Synced" then "Not-synced" and/or rpms jumping up and down. The tooth
logger (see section 8.3) should also be used to confirm that the pattern is stable if you do not have a
steady RPM. Keep working on the crank/cam sensor inputs until you have stable rpm with no loss of
sync.
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While cranking, take a look at the fuel load (MAP sensor) reading in TunerStudio, if you are running
speed density. You should expect to see it drop slightly as the engine pulls some vacuum. If it stays
stuck on atmospheric pressure (near 100 kPa) then your map hose might be connected incorrectly.
6.1.3 Setting cranking timing
Having confirmed that the coils work as expected and with the fuel pump still disconnected, hook up
a timing light to plug lead #1. Yes, this is really needed - correct timing is very important. If you are
running wasted spark you need to ensure your strobe is compatible. "Dumb" timing lights are fine;
some dial-back lights can be awkward. Use a "2-stroke" setting for wasted-spark or wasted-COP if
you have a dial-back light. With a coil-on-plug pencil type coil you will need to remove the coil from
the engine and install a short length of regular spark plug wire from the COP to the spark plug, and
possibly ground the COP if it was bolted on. Connect your timing light over this temporary plug lead.
If there are no timing marks on your engine, you will need to add some sort of marks. You can
establish TDC with a piston stop and add timing marks with either paint or timing tape.
Crank the engine and confirm that #1 timing is somewhere close to the Cranking Advance number
set in TunerStudio (this is set in section 5.3). If the timing doesn’t match and you’re in Fuel Only mode,
you’ll need to adjust whatever is controlling the timing. Otherwise, you’ll need to adjust the Tooth #1
Angle setting (if running Toothed Wheel) or Trigger Angle / Offset (if running any other spark mode
besides Fuel Only). If the timing is too far advanced, increase this number. If the timing is retarded,
decrease this number. If adjustments of more than 10 degrees are required, making the change, click
Burn, turn the key off and restart the engine. Very large changes don’t take effect until you turn the
MS3-Pro off and back on again.
6.1.4 Starting the engine
Now that you’ve confirmed sensor inputs, coil and injector outputs, have good rpm and cranking timing
is close you are ready to start the engine. Ensure the fuel pump is connected (since we disconnected
it in previous tests), battery is charged, and all hoses are secure. We recommend starting a data log
as well. While the engine will usually start if you’ve gone through all the previous steps for setting
up MS3-Pro, sometimes you’ll need a couple more tweaks, and the data log can be very valuable if it
comes to that. Go to the Data Logging menu, select Start Logging, and enter a name for your data
log. The log starts when you click Save, and stops when you either close TunerStudio or go to the
Data Logging menu and select Stop.
Now, hit the starter, and hope the moment for the big payoff has arrived.
It is common to need to give the engine a little throttle to keep it alive on the first start. If all sounds
well, then keep the engine running and warm it up. Check for oil pressure, coolant temperature etc. If
anything sounds wrong - stop and investigate.
Take your time! If things aren’t working out, then take a breather and come back another day.
Come to the www.msextra.com forum and ask for help. When posting, please include full details
of your install: engine type, make, model, ignition setup. The forum is global and we might not be
familiar with your engine, so just quoting an engine code is not sufficient. Don’t use the forum to vent
your frustration, keep it calm...
If the engine kicks back, your timing is too advanced. Disconnect the injectors again and check
with a timing light. This can damage the starter motor if you ignore it.
If your engine does not spark, in spite of having a functioning fuel and ignition system and timing
that appears to be correct, here are several things we recommend checking that commonly will cause
a no start condition.
• If you are running full sequential fuel and / or coil on plug ignition, try changing these settings
to semi-sequential fuel and wasted-COP ignition. This will rule out the possibility that the cam
sensor hasn’t been set up correctly, and you’re firing on the exhaust stroke instead of the intake
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stroke. These changes will make it fire on both, which can be very useful for debugging startup
problems.
• It may be refusing to start because the fuel isn’t quite right. If the engine does not go above
cranking RPM, try adjusting the cranking pulse width (the Cranking Pulse menu under Startup
/ Idle). If the engine catches but dies immediately, try adjusting the afterstart enrichment (ASE
Percentage under Startup / Idle). Both of these are temperature dependent, so be sure you’re
adjusting them at your actual coolant temperature. There’s a couple rules of thumb you can use
here.
– Start at what you think may be a lean value, then work your way up in small increments.
– Pull a spark plug after a failed start and check the electrode. If it’s wet with fuel, decrease
the amount of fueling. If it’s dry, increase it. And if the electrode is covered with crud, your
problem may just be that you need new spark plugs.
– If the engine responds better if you give it a bit of throttle, you probably have too much fuel
(because the extra air helps get your air/fuel ratio closer to what it should be). So you need
less fueling. Conversely, if giving it the throttle makes things worse, you probably need
more fuel.
• Check for various physical problems. Some examples I’ve seen include coil packs or distributors
with one or two spark plug wires run to the wrong cylinders, a broken keyway on the crankshaft
pulley causing the timing marks to be 60 degrees off, and even a zip tie that got pinched in the
intake manifold gasket next to a coolant passage, which nearly hydrolocked the motor.
6.1.5 Setting running timing
Now that the engine is running, we can come back and make the final timing adjustments. Hook up
your timing light and start your engine. In TunerStudio, on the Ignition Options / Wheel Decoder menu,
set Fixed timing to "Fixed Timing" and click Burn.
This locks the timing to the advance you specify in the "Timing for Fixed Advance" box. You do not
need to alter your spark table.
• Enter say 15 degrees (or another angle that your engine will idle easily at.)
• Using your timing light, confirm that the timing on the crank matches the fixed advance you
entered at idle.
• If it does not, then adjust your tooth#1 angle (trigger wheel) or trigger angle/offset (other spark
modes.)
• If the actual timing is more advanced than MegaSquirt thinks, then increase the trigger angle/offset. If adjustments of more than 10 degrees are required, making the change, click Burn,
turn the key off, and restart the engine.
• Once you idle timing is matching up with your fixed angle, increase the engine revs and confirm
that the timing does not drift.
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If you get a large timing advance with increased rpms on a VR sensor distributor then it is likely that
your ignition input capture is backwards. It is also possible that your spark output setting is wrong
- however, exercise caution in changing this, as the wrong setting can damage your coils or ignition
module. If the timing retards a little as rpms increase you can make a correction by adjusting the
Spark Hardware Latency setting. The larger the number, the more compensation it will apply.
Do not proceed any further with your install if you cannot get stable timing. Note that “stable
timing” is a matter of degree - a small block Chevy with a HEI distributor and a worn timing chain, for
example, may have 2 or more degrees of timing jitter in normal operation. And many dial-back timing
lights will have problems keeping up with rapid changes in RPM. But if you are seeing the timing
bouncing around by 10 degrees or more, stop and investigate what’s wrong.
When finished, be sure to turn off the Fixed Timing and return to Use Table and click Burn.
6.2 The basics of 3D tuning tables and load types
At this point, a lot of your tuning from now on will involve 3D tuning tables, so this would be a good
point to explain what these tables are and how to use them. Here’s an example, in this case, an AFR
(air/fuel ratio) table.
These tables are called 3D tables because they can be drawn as a shape in 3 dimensional space.
The first dimension, the X axis, is pretty much always RPM for the 3D tables in MS3-Pro. The Y axis
is a load variable, usually expressed as a percent. It is possible to use different load methods for
different tables; you don’t have to use the same load type across the board.
• In speed density mode, the fuel load corresponds directly to the MAP sensor reading, and 100
kPa is taken to be 100% fuel load. Numbers over 100% are possible and indicate boost.
• In Percent Baro mode, the number is the MAP sensor reading divided by barometric pressure,
so 100% is when the MAP sensor and barometric pressure readings are equal.
• In alpha-N mode, the load is the percent throttle opening.
• In ITB mode, this number is a blend between the MAP sensor and throttle position opening.
We’ll cover this in more detail in section 7.
• In MAF mode, the MAF load is a synthetic MAP load number that is a percentage of the air flow
that the engine would draw in at 100% volumetric efficiency at its current RPM. For example, if
you have a 5.0 liter Ford V8, it would theoretically draw in 2.5 liters of air every crank revolution
(since only half the intake valves are open in a given rotation) at 100% volumetric efficiency.
If this engine is turning 2000 RPM, it would theoretically pull in 5000 liters of air in a minute.
If it’s only pulling in 2500 liters a minute, you get a MAF load reading of 50% load. MAF load
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numbers over 100 would indicate either a race engine with a very efficient intake design or
positive manifold pressure. The MAF load numbers do not directly match actual MAP sensor
readings, but in the absence of a MAP sensor, they’re a bit easier to get a simple 0 to 100%
value for your load.
• Some 3D tables have numbers that are a direct sensor reading; for example, you can set the
generic PWM outputs to work as a function of RPM and coolant or air temperature.
The third dimension is the number entered into the table.
TunerStudio lets you adjust the numbers on the load axis. Clicking on the gray boxes to the side
will bring up a prompt to change the values, shown below. Note that the values start at their lowest
point at the lower left hand corner and go up - if you have the values go backwards, this can cause
an error.
The two green arrow buttons in the upper right hand corner allow you to save (up arrow) or load
(down arrow) the table as its own separate file. An exported table will not include the rest of the tune,
and can be useful if you’re sending tune values from one MegaSquirt variant to another.
The buttons to the right of the green arrows allow you to adjust several cells in the table at once.
Simply drag the mouse to select several cells, and then click the button to adjust them. The buttons
work as follows:
• The equal sign sets all selected cells equal to the value you enter.
• The up triangle increases all selected cells by one increment.
• The down triangle decreases all selected cells by one increment.
• The minus, plus, and multiplication signs use the math operation you requested and the number
you enter on the selected cells.
• The last item may look like a divide sign, but it interpolates between selected rows instead.
The two blue arrows at the bottom of the cell stand for Undo and Redo. The Burn button writes
(“burns”) the data to flash memory, and the close button closes the table. Note that changes to the
cells will take effect as soon as you enter them, but if they are not burned to flash memory, the
MS3-Pro will not keep the changes after it shuts down.
When the engine is running, a blue dot indicating the current RPM and load will appear on the
table, and the nearest cells under the dot will be highlighted in yellow. The MS3-Pro interpolates
between the closest four cells if the engine is not directly on top of a load point.
The 3D view checkbox at the top of the table will change it to a three dimensional drawing with a
different set of commands.
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You can rotate the drawing with the mouse to get a better view, or press Z to toggle a flat overhead
view. When the engine is running, a blue dot will appear showing what RPM and load point the engine
is currently running at. The red dot shows which cell you are currently adjusting. Use the arrow keys
to move the dot around the map, and shift-up arrow or shift-down arrow to move the map value up or
down. Checking Follow Mode will cause the red adjusting dot to follow the blue dot around the table.
Many of the tuning maps can also be viewed under the 3D Tuning Maps menu. This brings up
both a 3D table and a bank of gauges to let you monitor the status of the engine while the table is
active.
You may change the gauge style to “Histogram” to change them to a line graph, or right click any
gauge to swap it to a different gauge style if you want to see different variables.
6.3 Tuning fuel
Once you have the engine up and running, it’s time to start tuning. There are three tools to use
for tuning when the engine is in a steady state: the VE table, the AFR table, and the settings that
define the injector behavior (Dead time and small pulse widths). We’ll cover the last two first as they
are applied across the board, so you will want these pinned down before you start tuning the whole
table. After these are dialed in, you can come back and dial in the acceleration enrichment and other
enrichments applied to the fueling.
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6.3.1 Dead time
The dead time (or offset) of an injector is effectively the portion of the pulsewidth when no fuel is
injected, this is because the injector is an electro-mechanical valve and takes a measurable time
to open and close. (Note that documentation for some earlier MS variants referred to this as just
"opening time".)
Setting the dead time correctly is an important setup step. If it is incorrectly set, you will find tuning
light-load or idle very tricky and features such as air-temperature correction will malfunction. In worst
cases your engine will be untuneable - especially if you have very large injectors.
The MS3-Pro dead time system is found on the Fuel Settings -> Injector Dead-time. It allows
for individual or grouped setting of these dead times. This will match up with the "Main fuel outputs
setting" on the engine and sequential settings page.
There are three main areas on this page:
• The injector settings on the left side.
• The voltage correction curves on the right side. These allow fine tuning the battery voltage
correction of the dead time.
6.3.1.1 Injector settings As previously mentioned, the injector outputs directly support high-impedance
injectors. Low impedance injectors may be used through an external peak-and-hold box or resistor
pack.
The first setting Same/Individual allows either one dead-time across all injectors, or if you have
physically determined the precise dead time for each injector individually, you can use the Individual
setting. Normally, use Same. The table below allows entry of the dead times - in milliseconds at
nominal 13.2 volts. You can choose one of the four battery voltage correction curves. (If in doubt, pick
no.1 and leave the curve alone.)
Typical dead times at 13.2 volts:
• High impedance injectors - dead time = 0.8-1.0 ms
• Low impedance injectors with resistors - dead time = 0.8-0.9 ms
• Low impedance injectors with external peak/hold - dead time = 0.6-0.8 ms
LPG injectors may require larger dead times.
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We’ll cover measuring injector dead time in more detail in the Advanced section.
6.3.2 Small pulse widths
At most pulsewidths (say above 2ms), injectors behave in a linear manner, where 10% increase in
effective pulsewidth gives a 10% increase in fuel flow. The MS3-Pro normally relies on this linear
behavior for fuel calculations. However, at small pulsewidths, injectors behave non-linearly. This table
allows for you to correct for this. You may specify up to four separate curves if you determine that your
injectors do not all work the same.
The Injector Small Pulsewidths feature allows the user to make a correction and make the nonlinear region more linear in nature. Unless you have calibration data for your injectors measured on
your MegaSquirt, this feature should be left turned off. The X-axis of the curve is the MegaSquirt
pulsewidth (before deadtime is applied) and the Y-axis is the required injector pulsewidth (before
deadtime) that the injector needs to approximate linearity. Most injectors observed exhibit an "S"
shaped non-linear region. Nothing happens for the first few 0.1ms after dead time, so a curve that
effectively adds on PW to the very low values will help linearize this somewhat. The non-linear region
also frequently shows a "lump" which will make linearization tricky. See the dead time measurement
section for real measured data.
Here are some example curves based on data from real injectors. Note that no allowance is made
for the "lump" which will distort the results. The injectors were linear by 1.2ms (plus dead time) so the
curve is arranged from 0-1.2ms.
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Ensure that the start and end points match. In this example, the curve starts at 0.000, 0.000 and
ends at 1.200, 1.200.
However, the best approach is to avoid operating injectors in this non-linear region altogether. Size
injectors appropriately and use a second set of staged injectors if a large dynamic range is needed.
6.3.3 AFR table
The AFR table can be used in three different ways.
• In MAF mode, it is your primary fuel table.
• In all other fuel modes, it can be used purely for closed loop O2 correction with a wideband O2
sensor.
• If you set “Incorporate AFR Target” under the General Settings menu to “include AFRtarget,” it
will scale the pulse widths based on the numbers entered.
We recommend using the “Incorporate AFR Target” option on most installs. This allows the VE table
to closer reflect actual volumetric efficiency, and allows you to specify the air/fuel ratio by directly
adjusting this table.
We took a brief look at this table in section 6.2. Now, let’s take a look at how you use this particular
table.
You’ll enter the AFR you want at each RPM and load point (see section 6.2 if you need a refresher
on the load points.). Most sequential fire engines will run best at 14.7:1 at idle. At cruising RPM and
low load, you can run 14.7:1 or sometimes leaner depending on the engine. Most naturally aspirated
engines tend to run best at 13.2 to 13.5 at full throttle, while engines running forced induction may
need to run as rich as the mid 11’s under boost. The Tools menu in the upper left hand corner lets
you bring up an AFR table generator.
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In this menu, you can enter information about the engine at left. The “X and Y Axis” option gives
you the option of retaining the current load and RPM bins, or generating new ones based on the data
entered. First, click Generate to create the table, then the Apply button to activate the new table or
Cancel to close the generator and not use the generated table.
If you are running MAF mode, this is your main fuel tuning table. If you do not hit the actual AFR
targets, you will need to adjust the MAF flow curve under the Basic / Load Settings menu.
If you set “Incorporate AFR Target” under the General Settings menu to “include AFRtarget,” this
table is used to scale the fueling. A table entry of 14.7:1 will mean no fuel scaling. Numbers less than
that will increase the fuel, and numbers higher will decrease the fuel. When using this mode, you’ll
tune your VE table to hit your AFR targets, then adjusting the AFR target table will directly adjust the
fuel to the desired AFR number.
6.3.4 VE table
The VE table is your primary tuning table unless running in MAF mode (and in MAF mode, it can be
used as a corrective trim table). At its simplest, bigger numbers equal more fuel.
In any mode that uses this table, the numbers in the VE table are a percentage. The fueling
equation takes the base pulse width from Required Fuel, scales it by the percentage in the VE table,
and then applies any other corrections, enrichments, and the like, such as air density correction
and warmup enrichment. If you have the tuning set to incorporate the AFR target, theoretically, the
VE table will match the engine’s actual volumetric efficiency. Don’t be alarmed if you need to enter
numbers above 100, particularly in boost. The maximum number is 255.
If you are running in MAF mode with the VE table enabled as a trim table, start by adjusting all
cells to 100. The table will apply a percent trim to the fueling calculated from the MAF sensor curve
and AFR table.
We recommend first setting up an appropriate AFR table, then adjust the numbers in the VE table
(upwards to add fuel, downwards to take it away) until your actual air/fuel ratio hits the target table.
Before starting to tune the VE Table, it is recommended that you turn the Acceleration Enrichment
(AE) off so you can see whats happening to the mixture as a direct result of the table rather than
having fuel added from Accel Enrichment. See the next section on how to switch this off. You may
find that youll need to be light on the throttle, as the AE is needed to fill "holes" that occur when the
throttle opens quickly. Remember to tune the AE when you have a tuned VE Table.
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Another item to turn off during tuning is the Overrun settings as the PW may drop to 0.0mS causing
lean spots. You’ll find this by going to the Basic / Load Settings menu and selecting General Settings.
Overrun fuel cut is in the lower right corner. The default tune has this turned off.
Tuning the VE table involves richening (by increasing the VE) or leaning (be decreasing VE) at
each point in the VE table. Most of your driving will occur in a diagonal strip of the VE table, from low
rpm, low kPa (i.e. idle) to high rpm, high kPa (i.e. WOT). You can adjust these values using the O2
sensor, data logs, VE Analyze Live in TunerStudio, and/or the seat of your pants. Low rpm and low
kPa (say less than half of the max rpm and max kPa) might be able to use stoichiometric or leaner.
Richer mixtures would be used at high rpm and high kPa.
However, the low rpm/high kPa and high rpm/low kPa are not seen as often driving your vehicle.
Basically, if the engine never runs in certain parts of the MAP, then the numbers there should not
matter. However, since you may not be able to guess where you will run under every possible set of
conditions, you put estimated VE numbers that make sense into the little used areas.
From this frequently used diagonal strip of the VE table, you will be able to see how much the VE
rises from one rpm bin to the next, and use these differences to estimate the low rpm, very high kPa
numbers and the high rpm, very low kPa numbers. Since you rarely (if ever) run in these parts of the
table, the actual numbers will not make much difference, but they will be there "just in case". You are
looking to create a smooth VE map wherever possible.
It is a good idea to set either the second or third row of kPa bins in the VE Table to the idle MAP
value. So, for example, if you idle at 35 kPa, set the first to say 20 kPa or even a little lower (this can
be used for fuel saving during over run). The second can then either be 35 kPa or a value between 20
and 35, with the next row being 35. The reason is it is always easier to tune idle if the point of idle is
on a cross hatch; then there’s only really 2 points that influence it rather than 4. The engine may not
always idle at the same MAP value when under load, but it’s worth trying to set this up for unloaded
idle. Most of the time, an engine will idle best if you flatten out the cells above and below where it
idles; it’s rare for an engine to need large changes in VE at idle.
6.3.5 Basic acceleration enrichment (AE) tuning
MS3-Pro has two options for basic acceleration enrichment, plus model based acceleration enrichment that we’ll discuss later. One is the time based accel enrichment setup that users of previous
MegaSquirt variations will recognize. The other one behaves similar to an accelerator pump on a
carburetor. We recommend using the accelerator pump style in most cases, but we will cover both
styles if you prefer the “classic” MegaSquirt setup.
Both use variables called TPSdot and MAPdot. The “dot” is a calculus notation that indicates rate
of change with respect to time. Don’t worry, you don’t need to know calculus to tune this. The amount
is expressed as a percent of change over time. With TPSdot, it is percent opening versus time; a
TPSdot rate of 100 %/sec would be opening from closed to wide open throttle in one second, or the
equivalent speed, such as going from 25% to 75% throttle in 1/2 second. The MAPdot is measured
in kPa per second. MS3-Pro can use either one, or a combination of the two, to trigger acceleration
enrichment.
6.3.5.1 Main accel enrich settings menu This menu allows for several changes that affect both
AE modes.
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• Use Time-based or Accel-pump Accel: This lets you select which of the two methods below
will be used.
• Wall-wetting AE (EAE, X-Tau): Enables model based acceleration enrichment, discussed in
section 7.
• TPSdot uses %WOT: This allows you to specify a curve that defines the upper limit of throttle position as a function of RPM. Moving the throttle beyond this point does not allow in any
additional air, and therefor triggers no additional acceleration enrichment.
• X-Tau MAPdot Thresholds: The X-Tau acceleration enrichment, when enabled, will always
trigger when the MAP readings increase. However, you can prevent this from automatically
triggering when the MAP sensor decreases by specifying a minimum amount of MAPdot in kPa
per second to trigger X-Tau.
– Start Transition - A MAP decrease at a rate slower than this will not trigger X-Tau fuel cuts.
– Finish Transition - When the MAP sensor reading drops faster than this, full X-Tau driven
fuel cuts are in effect. Between the start and finish values, the MS3-Pro will ramp in this
feature.
6.3.5.2 Accelerator pump AE The accelerator pump AE uses one curve each for MAPdot and
TPSdot driven acceleration enrichment. The enrichment starts as soon as the MAP or TPS reading
changes, and stops when the reading stops changing. The % number is a multiplier which multiplies
by Required Fuel to scale the pulse width up (or down; you can set negative multipliers when the MAP
decreases or the throttle closes and pull fuel at this point) for acceleration enrichment. The curve lets
you add a greater amount of pulse width at faster throttle openings or MAP rises. Zero on the curve
means no enrichment is added at that point.
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Underneath the curves, you have a line graph that appears when the engine is running. It tracks
the air/fuel ratio, MAPdot, and TPSdot measurements to help you tune the acceleration enrichment.
Besides the curves, you have the following settings.
• Accel enrichment TPS <-> MAPdot blend %: This percentage determines what percentage
of the acceleration enrichment comes from the TPS and what percentage comes from the MAP
sensor. 100% is entirely TPS driven, and 0% is entirely MAP driven. In between, the percentage
will scale the MAP driven pulse width adder down and the TPS driven pulse width adder up.
• Accel MAPdot threshold: The minimum MAPDot level needed to trigger MAP driven acceleration enrichment. Increasing this number will decrease false triggering from a noisy MAP signal,
but too much will mean you miss triggering acceleration enrichment at lower amounts of tip in.
• Accel TPSdot threshold: The minimum TPS rate of change needed to trigger TPS driven
acceleration enrichment. As with MAPdot threshold, this has similar trade-offs between setting
it too sensitive and not sensitive enough.
• Cold Accel multiplier %: This is applied whenever warmup enrichment is active. The MS3-Pro
applies the full amount of multiplier when coolant temperature is at -40 degrees. It tapers off in
a linear fashion to zero when you reach the point on the warmup enrichment curve where WUE
equals 100% and there is no enrichment.
• Accel Enrich Down-Scaling with RPM: The acceleration enrichment will begin tapering off in
a linear fashion once you reach the “Full Accel Below” RPM, and stop entirely once the RPM
exceeds the “Zero Accel Above” RPM.
6.3.5.3 Time Based AE
This is tuned under the Time Based Accel menu.
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The two curves are the primary tuning tools. They set the percentage of pulse width to add as a
function of the rate of change of MAP and TPS readings. The adder % is a percentage of the main
Required Fuel number. Under these charts, you can set a percentage to blend MAP and TPS driven
acceleration enrichment. 100% is entirely TPS driven, and 0% is entirely MAP driven. In between, the
percentage will scale the MAP driven pulse width adder down and the TPS driven pulse width adder
up.
Unlike accelerator pump AE, which stops when the throttle position or MAP sensor stops moving,
this mode will activate the acceleration enrichment for a defined time when the threshold rate of
change occurs.
Below that, you have a line graph that appears when the engine is running. It tracks the air/fuel
ratio, MAPdot, and TPSdot measurements to help you tune the acceleration enrichment.
Here are what the settings do.
• Accel MAPdot threshold: The minimum MAPDot level needed to trigger MAP driven acceleration enrichment. Increasing this number will decrease false triggering from a noisy MAP signal,
but too much will mean you miss triggering acceleration enrichment at lower amounts of tip in.
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• End pulse width: The amount of pulse width at the end of the acceleration event, as a percentage of Required Fuel.
• Time or Ignition Events: Allows you to specify the pulse width in either time or the number of
ignition events.
• Accel duration (events): If using ignition events, the number of ignition events where you will
receive full acceleration enrichment pulse width.
• Accel taper (events): If using ignition events, the acceleration enrichment will taper off to the
specified end pulse width amount over this number of ignition events after the accel duration is
complete.
• Accel time: The amount of time the full pulse width adder is applied, in seconds, when set to
time mode.
• Accel taper time: The amount of time after the accel time over which the pulse width adder
tapers off to the end pulse width number, if set to time mode. After this time, the amount of
added pulse width drops back to zero.
• Accel TPSdot threshold: The minimum TPS rate of change needed to trigger TPS driven
acceleration enrichment. As with MAPdot threshold, this has similar trade-offs between setting
it too sensitive and not sensitive enough.
• Decel Fuel Amount: A multiplier that is applied whenever the TPSdot or MAPdot threshold is
crossed down instead of up. 0% would trigger a total fuel cut, while 100% means no change
would be applied. The firmware will allow using values over 100% to add fuel in this situation,
although this is usually not a desirable effect. We recommend starting with 100% for a manual
transmission or 90% for an automatic transmission.
• Cold Accel Adder: This is applied whenever warmup enrichment is active, and is added to the
standard PW adder. The MS3-Pro applies the full amount of added pulse width when coolant
temperature is at the lowest temperature point in the warmup enrichment curve. It tapers off in
a linear fashion to zero when you reach the point on the warmup enrichment curve where WUE
equals 100% and there is no enrichment.
• Cold Accel Multiplier: This is applied whenever warmup enrichment is active, and is applied to
scale the pulse width by a multiplied amount before the cold accel enrichment number is added.
It tapers off in the same way as the Cold Accel Enrichment.
• Full accel below: Below this number, you will get full acceleration enrichment.
• Zero accel above: Above this number, the acceleration enrichment is completely off. In between these two numbers, the acceleration enrichment will taper off in a linear fashion.
The curve below illustrates how this works.
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6.3.5.4 Getting it dialed in Regardless of which of the two settings you use, many of the aspects of acceleration enrichment tuning will be the same. Before you start tuning the acceleration
enrichment, make sure your VE tables are dialed in. Adding a correctly tuned amount of acceleration
enrichment to an incorrectly tuned fuel table is still going to result in an incorrect amount of fuel. Since
the acceleration enrichment is stacked on top of the fuel the ECU is commanding based on the VE
table, you’ll want to tune AE last, after you’ve got the solid foundation of a well tuned VE table under
you.
The standard AE can be thought of like the accelerator pump on a carb, which shoots in some
extra fuel when you suddenly hit the throttle to compensate for the massive influx of air when you open
the throttle blades. The goal is to compensate for this influx of air for an instant during that transient
until the the transient is over and the VE tables are again providing the proper amount of fueling. If
your background is tuning carburetors, you can think of this as a very powerful fully adjustable/tunable
accelerator pump that lets you compensate for more than one rate of throttle position change. Slow
"tip-in" can be adjusted with a certain PW adder, medium with another larger PW shot, mid-fast with
another size PW squirt, and very fast throttle movements with another.
MAP based or TPS based AE? If you have a variable Throttle Position Sensor, we’d recommend
100% TPS based AE as a starting point. MAP based AE does the trick if you’re running an engine
without a usable TPS, but TPS based AE is generally easy to tune to the proper sensitivity level such
that it activates when you want it to, and not when you don’t.
Setting the TPSdot/MAPdot Threshold Levels First up, you need to determine what your TPSdot or MAPdot threshold will need to be. Below the line graph charts, you’ll see a TPSdot threshold
and a MAPdot threshold. These are the minimum amount of change of TPS position or MAP pressure reading, respectively, that are needed to trigger acceleration enrichment. Your goal is to set
these high enough that the acceleration enrichment won’t accidentally trigger at steady throttle, but
low enough that it’s sensitive enough to catch small or slow throttle movements as well. Setting it too
high can mean the AE won’t kick in when you need it.You want it as low as you can get it without it
causing AE to trigger when it’s not supposed to, such as during steady throttle.
Getting this dialed in can be done methodically, or by trial and error. Here’s the methodical method.
You’ll need to have a safe way to accelerate from the bottom to the top of a gear, preferably your 1:1
ratio gear, and you’ll want to datalog your engine idling, as well as these WOT pulls with your MS3-Pro
and TunerStudio. Ideally this is done on a dyno. Two to three pulls is better than one, but there’s no
need to get carried away. Then you can stop the datalogging and load this log up into MegaLogViewer.
In MegaLogViewer, on the left using the drop-down boxes that let you select what data you are
viewing in your logs, set one of these to TPSdot, and/or MAPdot. You can set another to TPS to show
you what throttle position you were at as well. Additionally, monitoring injector pulsewidth (select
PW in the log to view that data) is helpful too, as you’ll be able to see the commanded injector
pulsewidth including the extra fuel added during an AE event. Lastly, near the bottom right corner of
MegaLogViewer you’ll see four indicators. Accel, Decel, Bit 7, and Bit 8. If either Accel or Bit 7 are
active, that’s a Accel event and AE is adding fuel. If Decel or Bit 8 are active, that’s a Decel event and
AE is pulling fuel if configured to do so. (Accel and Decel are used for TPS Driven AE, and Bit7/Bit8
are for MAP Driven AE).
Next, look at the datalog section of the car idling. The TPS signal should be rock solid, no movement. If it’s jumping around, you have a noise issues on your TPS signal. This can be caused by ECU
sensor signal wiring that’s been routed too close to high voltage sources such as ignition coils, plug
wires, the distributor, etc. Re-routing those wires away from those high-voltage sources is always a
good idea. Additional possibilities for noise to get in the TPS signal could be a bad sensor ground
(be sure you’ve grounded it the MS3-Pro sensor return wire), or a faulty TPS sensor. Similarly noise
on the MAP signal could be electrical, but is more likely to actually be real movement in the manifold
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pressure, at least at the source you’re grabbing the vacuum signal from, meaning the port on your
intake manifold that’s connected to the MAP sensor.
If you’re seeing AE events at idle, your TPSdot or MAPdot threshold is set too sensitive (too low
of a number). You’ll see the pulse width bounce around when this happens as well; AE is just doing
what you told it to do.
Now look at the datalog sections for the WOT pulls, step through these in the logs and look for any
time AE activated (Accel or Decel). It shouldn’t be active at all on WOT pulls, because you’re at Wide
Open Throttle, you’re not moving the throttle around, so AE is not needed. Again, if you are seeing
AE activate during WOT pulls, your threshold is too sensitive.
In either case if you’re triggering AE when you shouldn’t be, you’ll want to increase the threshold
value a bit above the highest TPSdot (or MAPdot) value you see it reach in the logs. This is the lowest
you can set your threshold in order to be a sensitive as possible while not triggering at steady state
throttle (or idle, which is also steady state throttle, it’s the steady state of NO throttle).
Note this setting is also the same setting you should use for your lowest (slowest rate of change)
TPSdot or MAPdot field in the next section.
Tuning the tables Now that you have these, it’s time to tune the PW adder line graphs. To tune
these, start with the lowest speed throttle change position, and practice “tipping in” at that rate of
speed. Use the real-time line graph at the bottom of the page to see how fast you’re tipping in. When
you’ve gotten use to applying the throttle at the right rate of speed to be close to the TPSDot number
you’re using in the "slow" setting, watch your wideband o2 sensor readout. You want to be able to
determine what’s happening when you stab the throttle at that rate of speed. Is it going lean or rich?
Note that it’s hard to see this on a gauge, as often it will go one then the other really fast. You want the
first response; if it goes lean then rich you’ll usually see it hit 20:1 or maybe 22:1 for just an instant,
and then as it goes back to running purely the table it may go to 13:1 or whatever... you want to
watch that initial response, and if the first response is to go lean, then you want to add fuel; if the first
response is to go rich, you want to reduce fuel (PW).
A wideband o2 sensor is immensely helpful here, but don’t get too caught up in seeing perfect
AFR numbers through the whole transient event. Adjust it until it feels right, snappy and responsive
with no hesitation. The feel is more important than looking for perfect numbers. If you want perfect
numbers, you may want to try the model based acceleration enrichment. Setup basic AE first as
described here. Next you’ll adjust the other set points you’ve setup for faster throttle rate changes.
Repeat the process for the medium speed tip in, then the mid-fast, then the fast.
6.3.6 Startup / warmup fueling
On the first couple starts, you’ll want to use whatever combination of fuel and throttle can nurse the
engine along until it is warmed up, and dial in the fuel at idle while hot. The reason is that this setting
can affect startup behavior, and you will want to have good, solid values in the VE table (at least at
idle) before you can get final values for the startup sequence. Here is the sequence that MS3-Pro
fueling goes through while starting.
1. When the key is on, the MS3-Pro will turn the fuel pump on for 2 seconds and fire one priming
pulse to clear air for the lines. (You can disable this feature by setting the priming pulse to zero.)
2. When the engine starts turning, the MS3-Pro will run off the cranking pulse width table in batch
fire mode until the RPM rises above the cranking RPM threshold.
3. Once the RPM rises above the cranking threshold, the MS3-Pro transitions to the main fuel
table. It will initially multiply the pulse width from this table by the warmup enrichment (WUE)
and afterstart enrichment (ASE) combined.
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4. The ASE tapers off based on a user defined curve. After the ASE tapers away, the MS3-Pro will
run on the main fuel table multiplied by WUE.
5. When the engine reaches normal operating temperature, as defined by the WUE curve, the
engine will run on the main fuel table, and the warmup cycle is over.
Now, let’s have a look at the menus in more detail.
6.3.6.1 Cranking / Startup settings
• Cranking RPM: This is the RPM where the MS3-Pro uses cranking pulse width. You want this
to be high enough that the engine does not exceed this if turning at its “cranking, but doesn’t
catch” speed, but less than the speed it will settle into as soon as the engine has started.
• Flood clear TPS: When the throttle is open above this percentage below cranking RPM, the
MS3-Pro will conclude you are trying to clear a flooded engine, and turn off the cranking pulse
width.
• Cranking fuel pulse rate: The injectors are batch fired during cranking. This parameter lets you
inject fuel every ignition event or every other ignition event at double the cranking pulse width
number. Usually you would only use the “Alternate events” setting on engines with more than
eight cylinders.
• Priming pulse delay: This allows the MS3-Pro to wait a number of seconds after key on to fire a
priming pulse.
• Ignore MAT correction during ASE: This can be used to compensate for MAT sensors that
absorb heat from the engine. Turning this on will cause the air temperature correction to reset
to 100% until the ASE taper is over.
• ASE count units: You can specify the length of the after-start enrichment in engine cycles (every
other crank revolution for a four stroke) or tenths of a second.
Most of these use a tuning curve that specifies the amount as a function of RPM, like the chart below.
This one shows warmup enrichment; the other screens work the same.
On the left side, you have a graphic representing the amount on the Y axis and the temperature
on the X axis. The right side of the screen provides a handy temperature gauge and a table representation. (Click the “...” button in the upper right hand corner to hide or show the table.) You can either
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edit the numbers in the table or drag the nodes in the curve. Note that the entries must be set up so
that the temperature data points on the table are in order, from the coldest at the top to warmest at
the bottom. Accidentally setting the numbers in reverse order will result in incorrect operation.
6.3.6.2 Priming pulse This curve allows you to specify an initial pulse, in milliseconds, that is fired
on the first turn of the key to clear air from the fuel lines. You can set the pulse width as a function of
coolant temperature.
6.3.6.3 Afterstart (ASE) percentage This is a curve of percentage multiplier versus time. The
MS3-Pro will apply the full amount immediately after RPM climbs past cranking RPM and then taper
it off linearly through the ASE taper time. This number is added to the WUE number and then the
combined number is multiplied by the number the main fuel loop calculates. 0% is no afterstart
enrichment.
6.3.6.4 Afterstart (ASE) taper This curve is used to specify the amount of time that ASE is applied, in either cycles or tenths of a second. You specify which unit to use under Cranking / Startup
settings.
6.3.6.5 Warmup enrichment This curve is a percentage used to scale the fuel as a function of
engine temperature. 100% is no enrichment; lower numbers will take away fuel. This is not quite the
same behavior as ASE, which cannot be set to take away fuel. Just remember that ASE is an added
number, while WUE is a multiplier. Note that if the top number on this curve is not 100%, the engine
will not come out of warm up enrichment.
6.3.6.6 Putting it all together If the engine isn’t starting, pay attention to the RPM it runs through.
If the engine does not catch, but cranks at a steady RPM, you will need to adjust the cranking pulse
width. If the engine fires up, but then stalls in a few seconds, you will need to adjust the afterstart
enrichment. You cannot rely on an O2 sensor feedback for cranking, but here are some rules of thumb
you can use.
• It’s better to start off at a point you expect to be lean and add fuel in small increments, to avoid
flooding the engine.
• If giving the engine a small bit of throttle helps, you probably have too much fuel. Conversely, if
this makes it worse, you probably have too little.
• You can pull a spark plug and check if it’s wet with fuel, in which case you need to reduce the
fueling at the point where it stalled, or dry, in which case you need to add more fuel.
6.4 Tuning spark
Ignition is tuned on a 3D table like the AFR and VE tables.
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This table specifies the spark advance in absolute numbers in degrees BTDC (before top dead
center) as a function of RPM and load. The timing you see with a timing light should match the timing
table, unless there are spark trim tables in effect that make changes to it. We ordinarily recommend
tuning the spark map on a dyno, but here are a few general pointers for an initial setup.
The idea is that the idle and low speed areas are set to around 8-20deg. Usually idle will be around
8-15ř, but this depends on your engine’s design. If you set the first row in the RPM range as a little
under your usual idle (e.g. 600 if your engine idles at 800ish) and add some advance here this can
help stabilize the idle, so if the engine stumbles into this area the slight increase in advance will help
it to speed up a little so it doesn’t stall. The cruising area of the map should have a reasonably high
advance, (low to high 30’s) as the mixture will be reasonably lean and therefore will give a slower burn.
The overrun area can have an even greater advance, this will allow you to run lean in that section. At
Wide Open Throttle (WOT) the spark map needs to be RPM based (analogous to centrifugal advance
on an old style distributor) coming in at the right rate relative to engine RPM. Typically, you want it
"all in" by about 2800-3200 RPMs for a street performance motor, although many engines will benefit
from even more advance after the torque starts decreasing, something you can’t do with a mechanical
advance.
Note the the optimum amount of total advance is not necessarily the most that doesn’t cause
detonation. For example, with a modern cylinder head design, you might get maximum power at
32řBTDC on a large V8, but might not experience any detonation until 38ř- 40ř. However, you will
still want the advance to come in as quickly as possible (without knocking) up to 32ř. This number
won’t be 32 degrees for all engines; for example, we’ve found that the new Chrysler Hemi can have
problems at more than 22 degrees of timing at full throttle, and many small bore engines with pent-roof
combustion chambers run numbers in the mid 20 degree range.
When going into boost the advance table, values will need to be lower than when out of boost. A
common rule of thumb is that 1 degree of advance should be removed for every 2 psi of boost; this is
simply a rough guide, and lots of things can depend on how much to remove. Advance below 100%
load is often simply the flip side of retarding the timing under boost; as cylinder filling decreases, you
will need more timing.
6.5 Getting a good idle
Idle tuning has several components. One is how far the throttle is open - this can be adjusted with
the Idle PWM Duty Table or Idle Steps if you have an IAC valve, which lets you specify the valve
opening amount in terms of temperature. If you don’t have an IAC valve, you can use a set screw to
adjust the throttle blade angle. There is also closed loop idle tuning, which we will cover later in the
manual. Closed loop idle tuning targets a specific idle speed. But first, you need to get a stable idle
without closed loop tuning. If your idle is already hunting because of a bad tune, putting closed loop
on an idle that already has trouble will make it worse. We’ll take some time here to explain how to
tune your MS3-Pro for a smooth idle.The first key may surprise many novice tuners: The idle control
settings are not the most important thing to adjust to get a smooth idle.
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This may seem counter-intuitive, but consider this: If the engine is idling at constant load with the
throttle held at a constant opening, shouldn’t you have a constant idle speed? If your idle surges
or hunts under these conditions, and your idle control valve is staying at one opening value, the idle
control settings are not the problem. To get a steady idle, you need three things in place: correct fuel,
correct timing, and correct airflow. These problems should be addressed individually.
6.5.0.7 Correct Fuel Engines don’t like to idle lean; a lean air/fuel ratio is one of the biggest causes
of a surging idle. On an engine with sequential injection, this is simple enough - get the engine idling
at 14.7:1 for gasoline, and you’re good to go. Batch fire engines, however, have issues at idle with
intake pulse reversion sending some of the fuel into an adjacent cylinder. So, if your setup only allows
batch fire, you’ll need to add a little more fuel so all the cylinders can stay at 14.7:1 or richer. Batch
fire engines typically idle best in the mid 13’s, so if you’re leaner than that, put in some more fuel and
see if that stabilizes the idle.
You’ll need to make sure the air/fuel ratio is maintained during cold start. If your idle hunts when
the engine is cold, but stabilizes when it warms up, try more warm up enrichment.
6.5.0.8 Correct Timing Timing is a very useful tool for controlling your idle speed. Ideally, you’ll
want the timing to be set to slightly below the timing that would give it the most power - on most piston
engines, this typically works out to somewhere in the 10 to 18 degree range. Then you can add a row
around 300 RPM below your target idle speed if you find the idle to be unstable. The timing in this row
can be bumped up by around 2 to 4 degrees over the idle timing. The 3d view below shows a spark
table set up this way.
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Setting up your timing like this has a stabilizing effect on the idle. When the idle speed drops, the
timing advances, increasing power and moving the idle speed back up. The result is an automatic
feedback loop that helps maintain a constant idle speed. Not every engine really needs this. However,
you need to look out for timing curves that do the opposite. If you’ve specified less timing below the
target idle speed than you have at the idle speed, this often makes for an unstable idle as the ECU
pulls timing while the idle speed falls. This can make a slight disturbance in idle RPM amplify itself
into an idle speed that cycles up and down rapidly.
Too much timing can be trouble. If the timing at your regular idle speed already puts you at the
most power output, you have nowhere to go but down. Over-advanced timing will hurt power as well
- beyond a certain point, adding more timing will not bump up the idle, and taken to extremes, it can
do the exact opposite. So you want to "hold back" a little timing at your idle RPM and run less than
the amount of timing that would give it the most power.
6.5.0.9 Correct Airflow You’ll need to get the right amount of air to maintain a good idle speed.
How to do this depends on what sort of IAC (idle air control) valve you have.
No IAC valve at all? Yes, you can run without an IAC valve. Just use your idle speed set screw
to adjust it open enough that the engine doesn’t stall on cold starts. Sure, your idle speed with the
engine warmed up will be higher than it could be, and you’ll have no way to adjust for stuff like the
A/C or electrical loads, but it’ll work.
On/off IAC valves give you two choices: On fast idle, or off it. You’d set the idle speed set screw to
your desired idle speed with the engine warm, and if your on/off valve is big enough, turning it on will
keep the engine from stalling on a cold start. No closed loop control is possible. You can even add a
second on/off IAC valve alongside an existing IAC to kick up the idle when the A/C turns on. Nissan
used this on many early ’90s cars, although they paired it with a PWM IAC valve.
PWM IAC valves or stepper motor IAC valves are continuously variable. This lets you adjust the
amount of opening time as a function of temperature. There are two ways these can be run. Open
loop mode (also called warmup mode) simply tells the valve to open a set amount as a function of
temperature. Closed loop mode tries to maintain a target idle speed. We’ll cover closed loop idle
tuning and several of the MS3-Pro’s other idle control features, such as increasing the idle speed
when the A/C or cooling fan come on, under the Additional Items.
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ADDITIONAL ITEMS: BEYOND BASIC FUEL AND IGNITION CONTROL
7 Additional items: Beyond basic fuel and ignition control
The MS3-Pro will control a lot more than basic fuel and ignition. In this section, we’ll cover what else
the MS3-Pro can do, one menu screen at a time. We’ll skip the menu screens that were set up in
sections 5 and 6, and cover the rest here.
7.1 Basic / Load Sections
This section covers many basic aspects of the engine setup as well as very commonly used input and
output features.
7.1.1 General Settings
7.1.1.1 Barometric settings
• Barometric correction For vehicles that experience altitude variations, this setting enables an
automatic adjustment to fueling. See also the baro correction curve.
– "None" - disables the feature, if adjustment is not required or desired.
– "Initial MAP reading" - takes a reading from the primary MAP sensor at power on and uses
that single value. If your altitude changes greatly during a single journey, you may need to
stop and restart to take a fresh reading.
– "Two independent sensors" - uses a second sensor which is sampled in real time to update
the barometric correction continuously.
• Realtime baro port - when two sensors are enabled, this selects the input port you have the
second sensor wired to.
The next two settings are used to limit false readings in case of sensor failure.
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• Upper limit - the maximum barometric pressure allowed.
• Lower limit - the minimum barometric pressure allowed.
• Default baro - the typical baro pressure for your region. This is used as a the barometer value
if you have not enabled a sensor.
7.1.1.2 MAP sensor settings
• MAP sensor type - "Voltage" (by far the most common) or "Frequency" (used on a few Ford
or Cosworth engines) are supported. The most common frequency based MAP sensor most
enthusiasts may encounter is the one used on Fox body Mustangs.
• Voltage input port - where the primary MAP sensor is wired (when voltage is selected.)
• Frequency input port - where the primary MAP sensor is wired (when frequency is selected.)
• Low frequency - the frequency corresponding to the minimum pressure, if using a frequency
based MAP sensor.
• High frequency - the frequency corresponding to the maximum pressure, if using a frequency
based MAP sensor.
• 2nd MAP port - enables a secondary voltage MAP sensor and selects where it is wired
7.1.1.3 General Sensor Settings The MegaView is an add on display device from the DIY line of
MegaSquirt products. Ones built for the MegaSquirt-II will also work with MS3-Pro.
• MegaView temp units - Choose degC or degF to match your MegaView.
Lag factors force the variables to change more slowly than the actual input value, smoothing them
and reducing the effect of noise in the signals. Note that in all cases, 100% is no lag effect at all, and
smaller numbers slow the input response speed. Setting a lag factor to zero will completely paralyze
the input and prevent it from changing at all, normally not a desirable setting. Higher numbers can
give faster throttle response in many cases, but setting them too high can cause problems if you have
noise on the input.
The following inputs can have lag factors applied to them:
• MAP Averaging Lag Factor (also applies to MAF)
• RPM Averaging Lag Factor
• TPS Averaging Lag Factor
• Lambda Averaging Lag Factor
• CLT/MAT/Batt Averaging Lag Factor (these sensors run off a common number)
Auto-zero TPS - if TPS% is showing negative at power on, the current value will be taken as zero.
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7.1.1.4 Load Parameters These critical settings determine the engine behavior and select your
chosen load source. See section 5.2 for an explanation of the load types.
• Primary Fuel load - sets the primary fueling algorithm.
• Secondary Fuel load - enables an optional secondary blended fuel table. Most engines will not
need a secondary fuel load.
• Secondary Fuel - "multiplicative" or "additive" - whether the values in VEtable1 and VEtable2
should be multiplied or added together when the secondary fuel table is in use. Selecting “Blend
Curve” allows blending between two tables based on a curve (selected under the Table Choices
menu).
• Multiply MAP - For Speed-Density installs this should normally be set to "Multiply". This number
uses the air density, based on the MAP sensor reading, in the main fueling equation. If this is
turned off on a speed density install, the VE table values at low loads can be very small, while
any values under boost will head off to well over 100%. Turning this on will flatten out the table
and make it a bit more manageable. About the only reason to turn this off when running speed
density is on installs with a highly unstable MAP signal. Turning this on in alpha-N mode will
result in a mode that is something of a hybrid between alpha-N and speed density, as the pulse
width will be scaled for MAP readings.
• Incorporate AFRTarget - selects whether the target AFR value from the AFR table is used in
the main fueling equation. See the tuning section before changing this setting.
• Stoichiometric AFR - this is used with the previous setting. 14.7 is typically used for gasoline.
Many racing fuels may not follow this exact value; if you are changing from one race fuel to
another and know the stoichiometric point for both, this can be used to change the fueling
directly.
• Primary Ignition load - sets the load value for ignition table lookups.
• Secondary Ignition load - enables an optional secondary blended ignition table. The blended
fuel and spark tables can be used to effectively enlarge the table size. This table can be additive
or use a blend curve.
• AFR table load - sets the load value for AFR table lookups
• EAE table load - sets the load value for Enhanced Acceleration Enrichment curve lookups.
7.1.2 Rev Limiter
MS3-Pro allows for fuel or spark based rev limiting. You can also allow the rev limit to change as a
function of coolant, so as to set it low before the engine warms up, or even drop the rev limit if you
overheat.
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7.1.2.1 Hard rev limit
• Hard Rev Limit (RPM) - This is the point at which a fuel cut or complete spark cut is applied.
The coolant temp limiter, if used, will override this setting.
• Soft Limit Zone / Hysteresis - The RPM needs to fall this far beyond the hard limit before the fuel
cut is turned off. If you are using a spark cut or a progressive fuel cut, the cut will start to phase
in when you reach this many RPM below the hard cut as well.
7.1.2.2 Coolant temp limiter The curve defines an alternate hard rev limit based on coolant temperature. You can use this to limit RPM with the engine cold or to create a shut-off if the engine is
overheating, or both.
• Rev limiter coolant based – Normal - The above settings are used independent of coolant.
– CLT Based - the curve is used to select a rev limit based on coolant temperature, so that
lower limits can be applied to a cold engine. When selected, the graph on the right hand
side of the screen defines the rev limit.
• Rev limit TPS bypass% - above this TPS% the coolant curve is ignored, and it uses the rev
limit below it. This should be set to a high percentage number, so that only in an emergency
when you really need full throttle on a cold engine can you override the cold limit.
• RPM when in TPS bypass - rev limit when above the TPS% bypass limit.
7.1.2.3 Spark retard The MS3-Pro has several different spark retard strategies. You specify the
timing retard in an absolute angle which the MS3-Pro will use as your timing; the timing specified here
is not an amount of timing to pull but the total amount of timing to use. The spark retard begins at the
soft rev limit - the hard limit minus the soft zone number.
• Mode - Select how
– Off - no spark retard rev-limiting is used.
– Progressive Retard - the timing is progressively retarded between the “retard above” threshold and hard rev limit. The retard starts just above the "retard above" rpm and reaches the
maximum set retard by the "fuel cut" rpm.
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– Fixed angle - when the "retard above" rpm is reached the spark timing is immediately
changed to the rev limiter timing.
• Maximum retard - the maximum amount of timing retard that will be applied
• Retard to - the fixed spark angle that will be used.
7.1.2.4 Spark cut Where MegaSquirt is directly controlling spark, spark cut can be used as a rev
limiter method. This cannot be used with EDIS and will not work as expected with TFI, GMDIS or
C3I, as these systems have some level of independent spark control. Be aware that spark cut can
be harsh and should not be used with catalytic convertors due to the damage it causes. Frequently,
there will be some level of "popping and banging" and exhaust system damage may occur. Use at
your own risk!
The spark cut algorithm cuts sparks on a "round-robin" basis to prevent individual cylinders loading
up with unburned fuel. The cut begins at the soft limit value and the percent of sparks cut increases
up to the hard limit, where the MS3-Pro shuts off the spark entirely
7.1.2.5 Fuel cut This gives the option of an abrupt, total fuel cut, or cutting fuel to more and more
cylinders until a total fuel cut at the hard limit.
• Enable Fuel Cut Limiting - Turns on fuel cut rev limiter.
• Progressive Fuel Cut - If this is turned off, the fuel cut applies abruptly when you reach the
hard limit. If this setting is on, the MS3-Pro will shut off fuel to one cylinder at the soft rev limit
and ramp this up to cutting all cylinders at the hard limit. This does not rotate between cylinders
like the spark cut - once the cylinder is off, it remains off until the RPM drops enough to turn it
on. Note that this cannot be used with throttle body injection or staged injection. This
only works with one injector per cylinder.
7.1.3 Shift light
While a programmable on/off output can be set to work as a shift light, the MS3-Pro has a dedicated
function for this that allows separate shift settings for each gear. The shift light will need switched 12
volt power on one end and the MS3-Pro will supply ground. The light needs to be wired so it does not
receive power with the key off. The stepper outputs are an exception. Stepper Out 1A and Stepper
Out 2A supply 12 volt power when active.
• Shift light output - Specifies which pin is used for shift light output.
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• Per Gear Limits - Setting to On enables separate outputs per gear. Setting to Off uses a single
limit. Transmission gear sensing needs to be set up in the Speed and Gear Sensors settings
under Advanced Engine to use per gear limits.
• Limit - The point to turn on the shift light when not using per gear limits.
• 1st Gear Limit through 6th Gear Limit - Specifies when to turn on the shift light when using per
gear limits.
7.1.4 Tacho Output
The tachometer feature provides a pulsed output suitable for connecting to a tachometer (rev counter.)
The Tach Out pin will generate a 0-12V signal that will drive most aftermarket tachometers. The stepper output pins will also supply a 0-12V square wave. Some older tachometers may need additional
work if they are designed to use the pulse from a coil negative terminal or are current driven.
• Tacho output enabled - enables the feature
• Output on - selects the output pin
• Speed – Normal - an output pulse is generated matching each cylinder event. i.e. 4 cylinder engines
have 4 pulses per engine cycle.
– Half speed - output runs at half speed. This can enable a 4-cyl tachometer to be used on
an 8-cyl engine.
The tach output does not currently support other fractional speeds, such as running a 4 cylinder
tachometer on a 6 cylinder engine.
Note that you can select other channels for tach output, but these pulse from floating to ground.
To obtain a 0-12 volt signal from one of these channels, you can wire a 1K resistor from the output to
a switched 12 volt source.
7.1.5 Fan control
While you can control a fan by simply stating it comes on at one temperature and off at another, MS3Pro gives you more options. You can adjust the idle speed to compensate for the increased electrical
load, or factor in throttle opening or speed as well. Many cars have enough airflow at cruising speed
to not need an electric fan at that point, so you can shut it off to save power. The MS3-Pro outputs
can drive a relay; don’t wire them to the fan directly.
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• Fan Control On - Enables the MS3-Pro fan control
• Fan Control Idles up - Whether the fan activation should also raise the idle
• Output Pin - The output pin for the fan relay
• Idleup delay - how long to wait after raising idle before turning on fan
• Idleup duty - PWM open-loop duty cycle to increase by
• Idleup steps - additional stepper idle steps to open
• Idleup target rpm increase - target rpm to increase by (if using closed loop idle control)
• Fan on temperature - turn fan on above this temperature
• Fan off temperature - turn fan off below this temperature (must be lower than "on" temperature)
• Allow fan when engine off - allows fan to run in key-on, engine-off situation
• Fan on with A/C on - whether the fan should be automatically turned on to help cool the A/C
radiator.
• TPS shutoff - disable fan above this TPS% (reduces load on engine when max power desired)
• TPS hysteresis - the percent throttle opening that the TPS must drop below the TPS shutoff
before the fan comes back on
• VSS shutoff - disable fan above this vehicle speed (at high speeds airflow through radiator will
be sufficient on its own.)
• VSS hyst- the amount the speed must drop below the VSS shutoff number before the fan comes
back on
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7.1.6 Torque converter lockup
MS3-Pro has the ability to control electric lockup on automatic transmissions. This is for part-electric
transmissions (e.g. 700R4, A4LD) but not fully electric (e.g. 4L60E, 4L80E). As a minimum, TPS and
MAP are used to set lockup criteria. Optional criteria include an enable switch, brake switch, speed
sensor, or gear sensor.
• Output port - output port to connect to lockup solenoid
• Enable input - optional input port for enable switch. For example, some transmissions have a
switch that turns on in fourth gear to enable lockup.
• Brake switch - optional input port for brake light switch. The torque converter unlocks if this
input is active.
• Minimum TPS - minimum TPS to enable lockup
• Maximum TPS - maximum TPS to enable lockup
• Minimum MAP - minimum MAP to enable lockup
• Maximum MAP - maximum MAP to enable lockup
• Use VSS - optionally allow VSS1 or VSS2 speed input as criteria
• Minimum speed - sets minimum speed for lockup. (Requires VSS input in speed/gear sensors.)
• Use gear value - optionally allows gear number as criteria. (Requires gear to be enable in
speed/gear sensors.)
• Minimum gear - minimum gear to enable lockup
• Activation delay - wait this long after conditions are met before locking up.
The MS3-Pro can drive a 5A solenoid with a high current output, or up to 3A with a PWM output. If
you need more current, you will need to use a relay.
Note that these settings are not used if you have added on a MicroSquirt using the MicroSquirt
transmission control firmware - the torque converter lock up will be tuned from the MicroSquirt’s menu
instead.
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7.1.7 Barometric correction
This screen works similar to the warmup enrichment display, showing a percentage correction curve
as a function of barometric pressure.
The number is a multiplier, so that 100% indicates to use normal fueling. The barometer reading
is whatever the MS3-Pro is currently using for correction. If you have enabled a barometric pressure
sensor, the reading will change in real time. If you are using the initial MAP reading for barometric
pressure, it will display the MAP reading it sampled when the MS3-Pro initially powered up.
7.1.8 MAP sample settings
On an engine that is using the MAP sensor (most installs except pure MAF or pure Alpha-N) it is
important to get a repeatable and stable MAP sensor signal. Note that repeatable is more important
than "accurate". There are two schemes available
• Event Average - the MAP signal is averaged between each ignition event. This is useful for most
engines.
• Timed Minimum - the MAP signal is sampled in a defined sample window and the minimum
reading is used. This is useful mainly on 1,2cyl engines.
See also the MAP logger description.
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• MAP sample method - whether to use the Event Average or Timed Minimum method. When
Event Average is selected, no other settings on this page are required.
• MAP Sample Window - how wide the sampling window should be in degrees.
• No. Sample Events - how many windows to take the minimum across. For 1,2 cylinder 4-stroke
engines this should typically be set to 2 - more details below. For 2-stokes or larger numbers of
cylinders set to 1.
• Phase detect threshold - when using a MAP sensor in place of a Cam sensor (on 1cyl or
V-twin), this is used to detect the intake stroke.
• MAP sample timing - this curve sets the start of the sample window in degrees BTDC for each
ignition event. The number must always be less than the number of degrees per event. (720
divided by the number of cylinders: for a 4 stroke i.e. for 4cyl there are 180deg per event, for
8cyl there are 90deg.)
7.1.8.1 Event Average For the majority of engines, this scheme is proven to give the most consistent results. The multiple runners and overlapping intake events on a multi-cylinder engine lead to
resonance and pulsations in MAP that vary across the RPM range and load. Taking an average over
the cycle sidesteps these problems and gives a useable MAP reading for the fuel calculations and
other table lookups. Once this mode is enabled, the other settings on the MAP sampling page are not
needed or used.
7.1.8.2 Timed Minimum For some engines, particularly 1 and 2 cylinder four stroke engines,
where there are fewer and more intermittent intake events it is necessary to specify where MAP
sampling will occur in order to get a repeatable reading. Here is a MAP log from a 1 cylinder 4-stroke
engine.
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Observe the large variation in MAP signal during the 720 degree cycle. It can be seen that one
MAP window falls on the intake stroke (where the MAP reaches a minimum) and the next MAP
window is on the power stroke (MAP is near atmospheric.) On this engine it was important to set the
appropriate MAP sample angle and window width to capture the dip in MAP, and set the number of
events to 2, since the intake happens every two revolutions.
The ideal MAP sample angle may either be determined by:
• using the MAP logger (registered TunerStudio only) and opening the datalogs created in MegaLogViewer to ensure the MAP window aligns with the dip in MAP
• by watching the MAP gauge on the TunerStudio dash and adjusting the MAP sample angle in
(say) 10 degree steps until the minimum is found.
Note that on most engines the best sample angle will vary with RPM. The Window Width should be
set so that it covers the dip repeatably.
The sample data below shows a practical example from the above test engine with a short sample
of the data.
First - with No. Events set to 1.
Event no. Min MAP in window MAP used for fueling
1
70
70
1
98
98
1
70.5
70.5
1
98
98
The MS3-Pro is sampling the MAP reading on both the intake stroke and the power stroke; the
intake strokes have a low MAP reading, but the pressure on the power stroke is nearly atmospheric.
This results in the MAP bouncing around between 70 and 98 resulting in unpredictable tuning. Using
Event Average would be equally poor.
Now - with No. Events set to 2.
Event no. Min MAP in window MAP used for fueling
1
70
70
2
98
70
1
70.5
70.5
2
98
70.5
This gives a more realistic and more repeatable MAP signal and is a good start for tuning - the
atmospheric readings of 98kPa on the "dead" windows are ignored.
The Phase detect threshold is in use on this particular engine. It allows 1cyl and certain 2cyl
engines to run sequential fuel and spark without a cam sensor. The MS3-Pro "looks" at the MAP
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signal during the reading and compares it to the threshold to determine whether this is an intake
stroke.
7.1.9 ITB load settings
ITB tuning mode builds on the capabilities of the dual table blended tuning approach but solves one of
the more significant drawbacks to that tuning mode: it provides the blended Speed-Density/Alpha-N
behavior of the blended dual tables in just a single table. This single table approach is a significant
improvement as all the automatic tuning tools available through TunerStudio now work correctly with
the single table.
This new tuning mode introduces a new engine load type to MegaSquirt, the ITB load. This load
type is selected in the tuning configuration the same way that Alpha-N, Speed-Density, or blended
tuning are selected. ITB load is also available for the other tuning settings including AFR, Ignition,
and Enhanced Accel Enrichment.
The ITB Load is derived from a combination of MAP and TPS values as well as other ITB-related
tuning curves that all work together to create a calculated value that is used as the "ITB Load" and
applied to the Y axis of the tuning tables in the same way that MAP is used for Speed-Density tuning
or TPS is used for Alpha-N tuning.
7.1.9.1 ITB load VE table ITB Load tuning uses a single VE table to control fuel but this VE table
is partitioned into two regions, one for Speed-Density and one for Alpha-N tuning. There are two
tuning curves and a couple of configuration values that must be set up to correctly partition the VE
table for a given engine. The curves and values are:
• % Baro Switchpoint - The MAP value where tuning switches from TPS based to MAP based.
Default is 90% and works for most engines.
• Idle TPS Threshold - A minimum TPS value that must be met to allow the switch to TPS based
tuning to occur. This is sometimes useful in idle tuning.
• ITB Load TPS Switchpoint - A TPS curve that defines the TPS value across the RPM range
where the MAP value reaches the pre-defined %b baro switch point.
• ITB Load at TPS Switchpoint - A curve that allocates the amount of each VE table column that
will be allocated to MAP based or TPS based tuning.
The diagram below illustrates how the ITB load VE table is partitioned for dual use. The region of
greatest MAP change (below %Baro switchpoint) is tuned using Speed-Density based tuning. The
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region of greatest TPS change (above %Baro switchpoint) will be tuned using Alpha-N based tuning.
This is exactly the same technique used in the blended tuning, just applied within a single table.
7.1.9.2 ITB load TPS switch point curve This curve defines the TPS value where the MAP load
reaches %Baro switchpoint. This curve will be different for each engine and should be set up using
values obtained from log files from your engine. The curve tends to be fairly linear so you only need a
few data points to plot the curve. A data point at low, medium, and high RPM from a log file is usually
enough. A spreadsheet or just graph paper can then be used to establish enough data points to fill in
the table for this curve.
ITB Load tuning requires that the MAP signal be above the %Baro switchpoint and that the TPS
value be above the value defined on this curve to switch from Speed-Density tuning to Alpha-N tuning.
Therefore, you want this curve to be relatively accurate and you may even want to set the values on
the curve a few percent low to ensure that the TPS value has been met when the MAP reaches the
%Baro switchpoint.
Besides defining the switch point to Alpha-N tuning, this curve also establishes the lower TPS
value that will be used to interpret the range of VE bins allocated to Alpha-N tuning in the VE table.
7.1.9.3 ITB Load at TPS Switchpoint Curve This curve is used to allocate the bins on the VE
table to either Speed-Density or Alpha-N tuning. The area of the VE table below the curve will be used
for Speed-Density tuning and the area above the curve will be used for Alpha-N tuning. The shape
of this curve defines how much of the VE table will be allocated for use between Speed-Density and
Alpha-N tuning for each RPM column. You want to allocate the largest portion of the VE table at
each RPM to the tuning mode that has the most non-linear response. The lower RPM region typically
requires a little more Speed-Density definition range than the upper RPMs.
7.1.9.4 Putting it all Together - Calculating ITB Load The ITB Load VE table is defined as ITB
Load vs. RPM. The ITB Load should not be confused with MAP or TPS, it is neither. What the ITB
Load tuning algorithm does is calculate a load value based on MAP, TPS, and the two ITB Load
curves. This calculated load value is the Y axis of the ITB Load VE table; it can also be applied to the
ignition advance and AFR tables as well.
7.1.9.5 ITB Load Calculation in Speed-Density Mode When the throttle position is less than
the value defined in the ITB load TPS switchpoint curve or the MAP value is less than the %Baro
switchpoint, the tuning algorithm will take the array of cells from the VE table below the ITB load at
TPS switchpoint curve and interpret this array within the context of 0% to %Baro switchpoint load.
A couple examples that assume %Baro switchpoint = 90:
If you have allocated the region between 0% ITB Load and 60% ITB Load on your VE table for use
in Speed-Density tuning and your %baro is 50% then the VE value for 30% ITB load will be used. In
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this same example, a MAP value of 0kpa would use the 0% ITB load bin and a MAP value of just less
than %Baro switchpoint would use the VE value just below the 60% ITB Load value on the VE table.
7.1.9.6 ITB Load Calculation in Alpha-N Mode When the throttle position is greater than or equal
to the ITB load TPS switchpoint curve and the MAP value is greater than or equal to the %Baro
switchpoint, the tuning algorithm will take the array of cells from the VE table above the ITB load at
TPS switchpoint curve and interpret this array within the context of TPS position. The lower TPS value
used for this interpretation is taken from the ITB load TPS switchpoint curve and the upper TPS value
is always 100%.
For example, if you have allocated the region between 60% ITB Load and 100% ITB Load on your
VE table for use in Alpha-N tuning and also assigned a value of 10% TPS on your ITB load TPS
switchpoint curve then a TPS value of 55% would yield an ITB Load value of 80% and the VE bin for
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80% ITB Load would be used. In this same example, a TPS value of 10% would use the 60% ITB
Load bin on the VE table and 100% TPS would use the 100% ITB Load bin.
7.1.9.7 Tuning For Idle Air Control The Idle TPS Threshold % setting defines the minimum TPS
value required to allow the transition to Alpha-N tuning. This feature allows the fast idle MAP to exceed
the %Baro switchpoint without entering Alpha-N mode. On engines with aggressive cams with higher
overlap, it is possible for the fast idle MAP to exceed the %Baro switchpoint. When this happens, you
do not want to enter Alpha-N mode tuning since the throttle is still reading fully closed. The Idle TPS
Threshold % prevents you entering Alpha-N mode and you can use the warm up enrichment curve
to compensate for any tuning errors caused by being stuck at the maximum Speed-Density bin while
the MAP is greater than the %Baro switchpoint.
7.1.10 MAF options
Mass air flow (MAF) sensors provide a measurement of actual airflow through the intake system of an
engine. In its most basic form, the fuel required by the engine (in mass per second) is directly related
to the air flowing into the engine (in mass per second), so the MAF sensor should give a good basis
for the fuel equation. (By comparison, Speed Density uses RPM, MAP, MAT and VE to estimate the
mass air flow.) In practice, like any other sensor input, the MAF has its own quirks and can suffer from
reversion effects (particularly on "cammy" engines) where the air flow gets measured twice.
The MegaSquirt implementation of MAF consists of the following main elements:
• Engine and injector parameters
• MAF calibration curve
• Optional trim table
Before setting up the MAF options, be sure you have the right parameters set under Engine and
Sequential Settings. The critical settings to enter here are:
• Engine Stroke
• No. cylinders/rotors
• Number of Injectors
• Engine size
• Injector size each.
Having entered those details, click on the Required Fuel button to calculate the global fuel constant.
You may need to re-enter the numbers if the calculator doesn’t pick them up automatically. Make sure
you set the correct units.
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The MS3-Pro will need all these numbers to be entered correctly, as it calculates the required
pulse width to hit target air/fuel ratios, instead of using something along the lines of “send X pulse
width at Y RPM and Z air flow meter volts.”
You will also need to set these settings in the General Settings page.
• Primary fuel load is set to MAF
• Incorporate AFR target is set to include AFR target
• Stoichiometric AFR is set to 14.7 for petrol/gasoline.
• Ignition load is set to MAF (If MAF is also being used for ignition control)
Now, you’re ready to set up the MAF options screen.
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Note that you can configure the MAF sensor and datalog MAF without using MAF for fuel or
ignition control. This could be useful to ensure it is operating as expected on an existing install before
switching to MAF. Your Primary Fuel load would be set to something other than MAF.
• Sensor type - selects between 0-5V voltage input (e.g. most MAFs) or frequency input (e.g.
GM)
• Voltage input port - selects the hardware input pin where the MAF is connected. (See wiring
section above.) Or "off" to disable MAF readings.
• Frequency input port selects from four possible frequency input pins. (See wiring section
above.)
– Low frequency - the frequency the MAF outputs to indicate least air flow.
– High frequency - the frequency the MAF outputs to indicate greatest air flow.
• MAT correction curve - optionally enables a trim curve based on MAT sensor input.
• Use VE1 as trim table - optionally enables VE table 1 as a trim table. Fill the table with 100%
to begin with.
• MAF sensor range - sets the range to match your MAF sensor. Set this before loading a
MAF calibration curve. On gasoline, 650g/s ~800hp; 1300g/s ~1600hp; 1950g/s ~2400hp and
2600g/s ~3200hp. Use the lowest range suitable for better low-end precision.
• MAT correction table - this curve allows adjustment of flow values from the loaded calibration
curve.
• Use old-style calibration curve - select this if you want to use MAF in the “old way” as per
1.1.x and earlier. In this case, the calibration curve is not the actual flow curve, but a trim curve
applied to the calibration curve loaded in the Tools menu. See section 7.1.11 for details.
7.1.10.1 More about frequency based MAFs Some GM MAF sensors are known to give a frequency output rather than an analogue voltage. This has the potential advantage of not being susceptible to any ground differences. Due to the way that the frequency is measured, the reading becomes
more coarse at higher frequencies. At 10kHz the measurement has 1% accuracy, 15kHz is 1.5%. For
better repeatability, it is suggested to get a larger MAF and recalibrate in preference to running above
10kHz.
Be sure to set the minimum and maximum frequencies before altering the flow curve. Pre-defined
calibration curves are available for GM LT1, LS1, LSx MAFs. When using the 650g/s file (~800hp)
set the min/max frequencies to 1000Hz and 11500Hz. When using the 1300g/s file (~1600hp) set the
min/max frequencies to 1000Hz and 14125Hz. For larger flowing MAFs, a custom calibration will be
required.
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7.1.11 MAF flow curve
This will bring up the MAF calibration curve, showing airflow as grams per second as a function of
voltage. Ideally you should start with the curve that matches your actual sensor. Some examples are
provided in the software package that may be loaded with File > Load Dialog Settings.
(This one curve replaces the Calibration and Correction Curve that were used in previous firmware
releases.)
7.1.11.1 MAF Load As shown above, the primary fuel load is MAF because fuel required is directly
related to mass air flow. However, ignition, AFR, and other load based tables are not directly related
in the same way. While it would be possible to use MAF volts as the Y-axis on other tables, it would
mean that only a very narrow band of the table was used, and tuning would suffer. So instead of that,
the code calculates a synthesized load value called MAF Load. This behaves similarly to MAP in a
speed density system and should give a repeatable load value and allow tuning of those tables in the
conventional manner. Make sure the axes on the table are set to cover all MAF load values and RPMs
if the engine is turbocharged; as a rule of thumb, the highest MAF load will probably be higher than
the highest K Pa value the engine sees. When live tuning, the active cell will be highlighted.
A MAF only install will need to use MAF Load for spark and AFR table lookups. But, if you have
a MAP sensor installed you can choose to set "Speed Density" for spark and/or AFR which will then
use MAP as the Y-axis in the table. It is also possible to use alpha-N and tune the spark map based
on TPS.
7.1.11.2 Tuning Initially it is suggested to leave the trim table turned off. Ensure you have configured the basic engine parameters: number of cylinders, number of injectors, engine size, injector flow
and used the ReqFuel calculator to set ReqFuel. As noted above, set primary fuel load to MAF and
spark and AFR to use MAF. Configure the AFR table for your chosen target AFR values. Ensure that
the load and rpm axes cover your expected range; alter them to suit if needed. It is suggested that
EGO correction be set to "No correction" at this time. Having started your engine, your primary tuning
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tool at this point is to make tweaks to the MAF Flow curve so that the reported AFR from your wideband matches the target table you configured. (You can enable the AFR error gauge in TunerStudio
to see the difference between the two.)
Ignition tuning will be about the same, but do not try dialing in the final ignition table until you have
the final MAF calibration curve.
7.1.11.3 Using VE1 as a trim table If and only if you have exhausted tuning using the Flow curve
alone, you can enable VE1 as a trim table. This gives you a full trim table of MAF Load vs RPM. (VE3
is also available with table switching.) When first enabling VE1 as a trim table you will need to fill it
with 100%. Press CTRL-A, = and then enter 100. The table should now look as follows:
Adjust the table as needed to hit your AFR targets.
7.1.12 MAF correction table (old)
When using the older MAF implementation, you will enter the MAF calibration curve under Tools ->
Calibrate MAF Table. This curve is a percentage trim to correct the curve loaded from the Tools menu.
The MAF flow number is the number on the original calibration curve, and you apply a % correction
to adjust the curve.
7.1.13 MAF / MAT correction table
The MAF setup should automatically compensate for ambient air temperature as the mass flow is
measured. If it is found necessary to make small adjustments for air temperature, then an optional
correction curve may be enabled. Enabling this allows access to the MAT correction table on the
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Advanced menu. The default values of 0% mean that no adjustment is made. Small +/- percentages
can be used to tweak the fueling at these air temperatures.
Use this table if you are using MAF based fueling and you find your car runs differently under
different weather or temperature conditions.
7.1.14 Realtime Display
This tab allows you to monitor real time data from the ECU. The “Summary” tab gives line graphs over
time of the more commonly used channels, while All Output Channels gives a numerical readout of
more channels.
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7.1.15 Feature List Shiwing I/O Pins
This allows you to display all the pins in use. You can use this to check what wire does what
function, or check if you have accidentally assigned one pin to multiple functions. Features not in use
are grayed out.
7.1.16 I/O Pins Showing Useage
When TunerStudio is connected to the ECU, this presents the same information in a different
grouping - it shows each pin and what function (if any) is assigned to it.
7.1.17 Expansion I/O Pins List / Usage
This screen is similar to the I/O Pins Showing Usage screen, but does the same for devices connected
to the MS3-Pro via the CAN connection, such as a CAN-EGT or a MicroSquirt running IO Box or
transmission control code.
7.1.18 Gauge and setting limits
Allows you to specify RPM levels and maximum load values on the gauges, as well as the highest
values you can enter into the load and VE tables. The other settings are explained below.
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• Allow WUE Below 100% - The warmup enrichment is a multiplier, with 100% being no enrichment. Values under 100% will reduce fueling to less than the base fueling. This is ordinarily an
undersirable thing to do, so the MS3-Pro will lock you out of this. However, LPG and gaseous
fuels often use an evaporator or expansion device heated by engine coolant. When the engine
is cold, the evaporator delivers colder, denser fuel than normal, which may require reducing
warmup enrichment below 100%.
• Prefered Speed Units - This is used for speedometer gauges, boost by speed, and other speed
related functions.
• Prefered Length Units - This is used for entering tire size and similar parameters. The MS3-Pro
allows mixing metric and English units.
• Air Cooled Expanded CLT Range - Adjusts the default range of the coolant temperature gauge.
Liquid cooled engines seldom have a coolant temperature very far beyond the boiling point of
water, but if you’re measuring the cylinder head temperature with your CLT sensor, the temperatures can, and do, go much higher.
7.2 Fuel Settings
This contains all settings outside of the Basic / Load Settings related to fuel, other than ones for
nitrous control. Injector dead time, the injector small pulse widths, AFR table, and the VE table are
discussed earlier.
7.2.1 Injector timing table
This is a 3D tuning table where you specify the injection angle in degrees BTDC for the cylinder
receiving the injection. The Engine and Sequential Settings menu allows you to define whether this
angle is the beginning, end, or middle of the injection event.
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Injector timing is specified as a function of RPM and fuel load. Most engines run best if the injection
timing is completed before the valve opens, to allow the fuel to vaporize.
7.2.2 Secondary injector timing table
This timing table is used if you have enabled a secondary set of injectors, either with the Staged
Injection or Dual Fuel menu. While these injectors may need the same timing as the primaries,
secondary injectors that fire in an upstream direction or in an air horn often need different timing.
7.2.3 Staged injection
Staged injection allows the use of one set of small injectors for low-load and/or low RPM operation
of the engine with the ability to engage a second set of injectors at higher load and RPM when the
primary set of injectors would otherwise reach their maximum operational duty cycle. The MS3Pro’s staged injection function supports staging equally between the primary injectors and secondary
injectors during staged operation as well as staging completely to the secondary set of injectors. You
may either use the standard injector outputs A through H on a four cylinder, or use injectors I and J in
batch fire on engines with more than four cylinders.
If you have enough outputs to use timed injection on the secondary injection, the Secondary
Injection Timing Table is enabled (in addition to the standard injection timing table), so the user must
remember to tune secondary injection timing separately from primary injection timing.
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• Staged Injection First Parameter - This setting enables staged injection and sets the primary
staging parameter, which is used to determine when to engage the secondary injectors. This
setting includes the following options:
– Off - Staging disabled.
– RPM Stage at a specific RPM.
– MAP Stage at a specific MAP.
– TPS Stage at a specific throttle position.
– Duty Stage at a specific primary injector duty cycle.
– Table Stage based on the table included in the dialog.
For table-based staging, 0% means not staged at all, and 100% means fully staged. Anywhere
between 0% and 100% means partially staged. The firmware calculates the primary and secondary
pulse-widths based on the injector sizes specified elsewhere in the dialog.
• Primary Injector size (cc) - Size of primary injectors in cubic centimeters.
• Secondary Injector size (cc) - Size of secondary injectors in cubic centimeters.
• Transition fully to secondaries - This setting is used to determine whether the fully staged
state means that the primary and secondary pulse-widths are equal, or if the fully staged state
means that primaries are shut down completely and staging transitions fully to the secondary
injectors. The following settings are possible:
– Off - The fully staged state means that the primary and secondary injector pulse-widths
are equal.
– On - The fully staged state means that the primaries are shut down, and staging transitions
fully to the secondary injectors.
• Secondary Outputs - This setting controls whether the regular sequential outputs are used for
secondaries or the I/J outputs on the gray connector are used. This option is only available with
4 or less cylinders. The following options are possible:
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– Use Inj A -H if possible - Use the standard outputs A through H. The second stage is fully
sequential with this setting Available on engines with four cylinders or less.
– Use Inj I/J - Use the I and J injector channels in batch fire.
• Secondary V3 Alternate - This setting controls whether the secondaries (when using the I/J
outputs) alternate between injector channel 1 and injector channel 2, or inject simultaneously
on injector channel 1 and injector channel 2. The following settings are available:
– Alternating (2 squirts) - Alternate between injector channel 1 and injector channel 2. Note
that when in alternating mode, the firmware injects 2 squirts per cycle.
– Simultaneous (1 squirt) - Squirt fuel on injector channel 1 and injector channel 2 simultaneously. Note that when in simultaneous mode, the firmware injects 1 squirt per cycle.
• Gradual Transition - This setting enables the ability to gradually reduce the pulse width of the
primary injectors and gradually increase the pulse width of the secondary injectors as staged
injection engages. This setting is most useful when the secondary injectors are located far
away from the primaries on the intake tract. Gradual transition and associated settings are not
available when using table-based staged injection. The following settings are available:
– On - Gradual staging is enabled. The associated settings will be used to control how quickly
the secondaries are engaged.
– Off - Gradual staging is disabled. When staged injection engages, the pulse width will go
immediately to the fully staged width.
• Transition events (ign events) - This setting is used when gradual staging is enabled to determine how many ignition events it will take to go from no staging to fully staged.
• Primary reduction delay (ign events) - This setting is used to delay the reduction of the primary
pulse width by the number of ignition events after the secondaries start coming online. It is only
enabled when the gradual transition feature is enabled.
• Secondary Enrichment (ms) - This setting is used to inject more fuel on the secondaries than
the fully staged calculation determines. This is useful when there is a small lean spot just after
staged injection fully engages. This setting is only available when the gradual transition feature
is enabled.
• Primary staging threshold (units) - This setting is used to determine when staged injection
engages when using RPM, MAP, TPS, or Duty. It is not available when using table-based
staging.
• Primary staging hysteresis - This setting is used to determine when staged injection shuts off.
For example, if RPM is selected as the staged injection first parameter, and the primary staging
threshold is 4100, and the primary staging hysteresis is 300, then staged injection will shut off
the secondaries and return the primaries to their normal pulse width at 3800 rpm. This setting
is not available when using table-based staging.
• Second parameter - This setting is used to add a second method for determining when to
stage. Note that this setting should not be set the same as the first parameter setting. This
setting is not available with table-based staging. The following settings are available:
– Off
– RPM
– MAP
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– TPS
– Duty
• Secondary staging threshold (units) - This setting determines the RPM, MAP, TPS, or Duty
at which the secondary staged parameter allows staged injection to engage. This setting is not
available unless a second staging parameter is enabled.
• Secondary staging hysteresis (units) - This setting is used with the secondary staging threshold setting to determine when staged injection will shut off. This setting is not available unless a
second staging parameter is enabled.
• Secondary staging logic - This setting is used to determine whether both the primary and
secondary staging parameters must be met to engage staged injection, or if only one of the
parameters must be met. This setting is not available in table-based staging mode.
• Relay Output - Allows using a relay to power secondary injectors in systems where the primary
and secondary injectors are both wired to the same ECU output pin, with the secondary injectors
receiving switched power from a relay. This tends to produce a jerky, abrupt transition, and is
mainly in place to support plug and play applications where the factory wiring lacks separate
outputs for primary and secondary injectors.
• Relay Output Polarity - If set to normal, turning the output on turns on the secondary injectors.
Inverted turns this off to activate the secondary injectors.
• Pre-Relay Output - Allows activating a relay before the secondary injectors are active. This is
usually to allow a secondary fuel pump to pressurize the second stage injector rail.
• Pre-Relay Output Polarity - If set to normal, the pre-relay is turned on before turning the
injectors. If set to inverted, the pre-relay output is set to off before turning on the secondary
injectors.
• Pre-Relay Timer - Specifies the time, in seconds, between turning on the pre-staging relay and
the secondary injector stage.
7.2.3.1 Tuning Staged Injection Our recommendation is that on any setup with secondaries are
further up the intake tract than the primaries, that you should use table-based staging. It is possible to
achieve a much smoother transition to staged injection in all situations when tuning with this method.
7.2.3.2 Tuning Table-based Staged Injection The following tips should be followed when tuning
table-based staged injection:
• RPM and Load transition bins - Make the two RPM bins and two Load bins where staged injection first engages close together. Also make the staging percent jump to 10-20% almost
immediately (as shown in the dialog at the beginning of the staged injection section). This is
so that a very small amount of time is spent with the secondary injectors at or near the injector
opening time for those injectors. Spending a lot of time near the injector opening time can lead to
inconsistent fueling, especially if the secondary injector opening time has not been determined
and the default value is being used.
• Transition to 100% engaged - The transition to 100% engaged should be determined using
experimentation. In general, the transition should be set so that the primaries stay close to
their maximum duty cycle (80% is recommended) for as long as possible. This ensures that
reduction to the primary pulse-width does not result in a lean situation. The table displayed at
the beginning of the staged injection settings section is a good example of how to tune tablebased staging for a smooth transition on a naturally aspirated engine.
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7.2.3.3 Tuning All other Staged Injection Modes All staged injection modes that do not use the
table to determine the staging amount can be tuned similarly. The following tips should be used:
• Primary staging parameter - It is usually recommended that the primary staging parameter used
is Duty. This ensures that staged injection engages when the duty cycle of the primary injectors
warrants it instead of trying to guess what RPM or load will cause use of the secondaries to be
necessary.
• Secondary staging parameter - It is recommended that this parameter only be used with forced
induction engines. It should be used to ensure that staging is fully complete before going into
boost so that any lean spots caused by staging are gone.
• Gradual transition - The gradual transition code was introduced to try to solve the same problems
that table-based staging solves, notably the small lean spot in AFR briefly after staged injection
engages. It should be set to transition over as many ignition events as possible for the smoothest
transition. If doing this still causes a lean spot, the primary reduction delay can be used along
with the secondary enrichment setting to make sure that slightly more fuel than calculated using
the normal fuel calculations is injected. If enabling the gradual transition feature still does not get
rid of the brief lean spot after staging is engaged, it is recommended that table-based staging is
used.
7.2.4 Fuel sensor settings (Flex)
The flex fuel system allows the use of E85 or other ethanol and petroleum blended fuel mixes to be
used when a special fuel composition. sensor is fitted. The support is specifically based around
the use of a GM flex fuel sensor which outputs a varying frequency signal depending on the fuel
composition. This information can then be used to add more fuel and advance timing. Ethanol blends
need more fuel volume than unblended fuel and different advance. The basic system uses a two-point
system (low/high) and interpolates between the values. You can also use flex fuel to create a blend
curve, which is explained in the section on blend curves below.
• Flex fuel sensor - this enables or disables the Flex Fuel system
• Sensor port - where the sensor is connected. A GM flex fuel sensor typically has pin A as
ground, B as 12 volt supply, and C to the MS3-Pro Digital Switched In 1. Note that Digital
Switched In 1 is currently the only supported port.
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• Frequency (low) - the sensor output frequency to indicate a low blend condition (typically 50Hz)
7.2.5 AFR / EGO control
This screen allows you to set up closed loop O2 sensor feedback.
7.2.5.1 Basic EGO settings These settings are used to control the behavior of the closed-loop
EGO algorithm.
• Algorithm - There are three options here:
– Simple - This method of closed-loop EGO control is well-suited to use with a narrowband
O2 sensor. If the current AFR (or EGO voltage for narrowband) incorrect, the amount
of fuel being injected is adjusted by Controller Step Size every Ignition Events per Step
ignition events. This method often results in the actual AFR oscillating above and below
the target.
– PID - This method incorporates a Proportional Integral Derivative control loop which tuned
properly, adjusts the amount of fuel being injected to quickly get to the target, and then
maintains the target without any oscillation (when tuned correctly). You tune the three
proportional, integral, and derivative numbers below when this mode is active.
– No correction: The O2 sensor is used for data logging only and is not used for closed loop
control.
• Use EGO Delay Table - You can select how often the EGO correction is updated based on
either the number of ignition events or by using a 12 x 12 table that determines how often to
update the correction as a function of RPM and engine load.
• Ignition Events per Step - While closed-loop EGO is active and the EGO delay table is off,
how often the correction is run is determined by this setting. It is the number of ignition events
per correction.
• Controller Step Size - This setting is only used with the "Simple" EGO algorithm. It controls how
large each correction "step" is. So if the AFR does not match the desired AFR, and Controller
Step Size is configured to be 1%, each time a correction is made, that correction will be 1%.
• Use Authority Table - Turning this on will allow using a table to determine how the maximum
amount of correction that can be applied applied as a function of load and RPM. For example,
you might want to give a large amount of control authority while cruising at light throttle, but
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reduce controller authority to zero under boost to protect against the consequences of a failing
oxygen sensor leaning out the engine under load.
• Controller Auth - This setting controls the maximum amount of adjustment performed by the
closed-loop algorithm if not using the authority table.
• Only correct above (AFR) - AFR readings below this level are not used and correction is turned
off when your receive this reading. Used to turn off EGO correction if the sensor is out of its
accurate range.
• And correct below (AFR) - This parameter allows setting a maximum AFR for correction in
combination with the above setting.
• Active Above Coolant - Below the temperature defined by this setting, closed-loop EGO will
not activate.
• Active above RPM - Below the RPM defined by this setting, closed-loop EGO will not activate.
• Active Below TPS - Above the throttle position defined by this setting, closed-loop EGO will not
activate.
• Active below Load - Above the load defined by this setting, closed-loop EGO will not activate.
• Active Above Load - Below the load defined by this setting, closed-loop EGO will not activate.
• EGO delay after start - The time in seconds after engine-start before closed-loop EGO can be
activated.
• PID parameters - These numbers are used to tune the correction when the algorithm is set to
PID.
• EGO Sensor Type - This setting enables EGO control and allows the user to choose between
using a wideband sensor or narrowband sensor. The following settings are supported:
– Disabled - No EGO sensor enabled. Note that this will also disable AFR logging. If you
wish to log your EGO sensor information, but do not want to use closed loop correction,
enable your sensor type and set Controller Auth to zero instead.
– Narrowband - Sensor in use is a narrowband sensor.
– Wideband - Sensor in use is a wideband sensor.
• Number of Sensors - This setting is used to select the number of oxygen sensors in use by the
MS3-Pro. Up to 12 sensors can be configured.
7.2.5.2 EGO ports The EGO Ports settings allow the user to select the input port used to read the
signal from the oxygen sensor. The number of EGO ports available depends on the number of sensors
selected. The “Normal EGO” input is reserved for the primary O2 sensor, but you can optionally use
one of the three other analog inputs for the primary, or an O2 sensor on a CAN network. The second
and subsequent sensors may not use “Normal EGO”, but may use any spare analog input or a CAN
device.
7.2.5.3 AFR/EGO Sensor Mapping Use this menu to assign which injector channel is associated
with what O2 sensor input.
7.2.5.4 Tuning
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Simple algorithm with narrowband sensor A narrowband sensor is only accurate at exactly
stoichiometric mixtures for the fuel being used (14.7:1 for gasoline). At around 0.5 volts, the mixture
is stoichiometric. For leaner mixtures (above 14.7:1 for gasoline, above 1.0 lambda) the voltage dips
slightly below 0.5 volts. For richer mixtures, the voltage goes above 0.5 volts. This behavior means
that it is not possible to hold an exact mixture when running closed-loop with a narrowband sensor.
Because of this, the best algorithm to use with a narrowband sensor is the "simple" algorithm.
The simple algorithm adjusts the mixture richer if the sensor reads lean, and leaner if the sensor
reads rich. It adjusts Controller Step Size percent every Ignition Events per Step. This can lead to
a small oscillation in O2-based correction once the AFR reaches close to stoichiometric.
The following steps are recommended when tuning the simple algorithm with a narrowband sensor:
1. Ignition Events per Step - When first tuning the engine, this should be set to a fairly low number
(4-8) so that if the AFR is very far off, it is corrected quickly. Once the engine is better tuned,
this number can be switched to a higher number to gain more stable correction behavior (8-16
or more).
2. Controller Step Size - When first tuning the engine, this should be set to 2% so that when
correcting, the engine reaches stoichiometric quickly. Once the engine is well tuned, this should
be reduced to 1% to gain more stable correction.
3. Controller Auth - When first tuning the engine, this should be set to 20% or higher. Care must be
taken to watch how the algorithm is correcting. In some situations, it is possible for the sensor
to read very lean when really the engine is running very rich. Once the engine is tuned, this
should be set between 5% and 10%.
4. Engagement Settings - Most of the remaining settings control how and when the closed loop
algorithm is engaged. Engagement with a narrowband sensor should happen when the engine
is nearly fully warm, 500-1000 rpm above idle, below 80% throttle, below about 80% load, just
above the lowest load seen when barely pressing the throttle, and at least 30 seconds after the
engine starts. These settings are because the sensor must be hot to operate, must not be used
at high load due to the fact that the engine should be operated rich of stoichiometric, and must
not be used at very low load because the oscillations will cause the engine speed to oscillate.
Simple Algorithm with Wideband Sensor Tuning the simple algorithm with a wideband sensor
is essentially the same as tuning it with a narrowband sensor with the caveat that the AFR target table
is used to set the AFR target. It is still recommended that the EGO algorithm not be used at high
throttle position/load due to the fact that the accuracy of the wideband sensor decreases dramatically
with pressure and temperature changes caused by high load.
PID Algorithm with Narrowband Sensor When using a narrowband sensor with the PID algorithm, all the same recommendations for settings given in the section describing the Simple algorithm
should be followed.
Additionally, since it is nearly impossible to keep the narrowband sensor from oscillating, it is
recommended to start by tuning the "I" term until the target is reached with minimal oscillation. Once
this point is reached. It is recommended that very little (if any) "P" term is used since the "P" part of
the PID algorithm causes instantaneous reaction, and the response of the sensor is not proportional
to the distance from stoichiometric.
PID Algorithm with Wideband Sensor When using a wideband sensor with the PID algorithm,
the same steps as when using a narrowband sensor can be followed for tuning the "I" term.
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Additionally, since the response of most wideband controllers and sensors is linear with AFR,
a larger "P" term can be used to help correct for fast changes in AFR. Caution must still be used
however since there is a significant delay between the amount of fuel being injected changing and
MS3 registering an AFR change as a result.
Finally, a small amount of "D" term can be used to help slow response during very fast changes.
This helps reduce overshoot of the target.
7.2.6 Narrowband EGO targets
This is a 3D table that behaves like an AFR table, but instead of specifying a target air/fuel ratio, it
specifies what voltage from a narrow band the MS3-Pro should target.
7.2.7 AFR safety system
The "AFR Safety" System is designed to help you protect your engine from unwanted dangerous
lean conditions. Typically this will be used for wide open throttle and/or boosted conditions. It only
makes sense to use this feature with a wideband lambda sensor on an already well tuned engine. The
system compares the wideband EGO input against your existing AFR target table and a safety limit
difference table. If this situation persists beyond a time you specify, the engine will be shutdown as
a protective measure until you get out of boost, off the throttle and down in revs. NOTE This system
will only work if configured correctly and will not protect your engine against bad tuning or knock!
However, it is likely it would detect a failing fuel pump or regulator. A single faulty injector could easily
go un-noticed with a single wideband reading the average AFR. This shutdown mechanism is shared
with the EGT over-temperature settings.
Settings:
• Enable AFR Safety - This enables or disables the system
• Warning output - This can be used to turn on an output (such as a warning light or buzzer) as
soon as an over-lean condition is detected.
• Load axis - Typically choose MAP if running speed-density or TPS if running Alpha-N
• Check above load - The system only checks the AFR above this load.
• Check above RPM - The system only checks the AFR above this rpm
• Wait for - This delay allows for a brief lean-spike without tripping the shutdown. Set as low as
possible.
• Kill spark for - Initially spark is cut for this time and then fuel as well.
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• TPS below, MAP below, RPM below - normal engine operation resumes when all three conditions are met. The table on the right is the "safety limit" difference table.
Each install is different and it is up to the installer and tuner to decide on safe limits! The example
data in the screenshot above has the system only active above 95kPa and 2000rpm. Once in this
region, the safety limit difference table is the controlling factor. For example, if at a certain point you
have set your target AFR (AFR table) to be 11.9, and you then decide that a worst case of 12.3:1 AFR
is allowable, the safety limit table would have 0.4 in that position. i.e. allowed AFR = target AFR +
safety limit = 11.9 + 0.4 = 12.3
If then your wideband EGO sensor reports 12.4 or leaner, the warning output will be activated
immediately. (Typically this would connect to a dash mounted warning light.) If this situation persists
beyond the time limit (shown as 0.5 seconds here) then the shutdown mode begins. If the AFR
returns to a "safe" level before the time limit elapses, no shutdown takes place. Review datalogs
before setting this time. The lower it is, then the sooner the shutdown kicks in. This could help protect
your engine, but setting it too low may cause annoying false alarms.
The first step in the shutdown procedure is to cut spark for a specified time (shown as 0.5 seconds
here.) During this period fuel continues with the intention of cooling the engine internals, as the lean
condition is likely to have generated excess heat. On vehicles fitted with a catalytic converter, 0.0
should normally be specified, as catalysts are not designed to cope with raw fuel.
After the "kill spark for" time, fuel is also cut.
Normal engine operation will resume only when your Throttle, MAP and RPM are less than the
limits you set. In operation, if you trip the shutdown, the engine will suddenly die. While this will be
irritating, hopefully it is less so than the engine rebuild you might have needed.
7.2.8 Cylinder trim tables
These tables act like miniature VE tables and are added to each individual cylinder.
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7.2.9 Sequenced Batch Fire
These settings allow batch firing to be sequenced from a specific trigger number for repeatable phasing on each start if you are running batch fire fuel with a sensor input mode that allows for wasted
spark or coil on plug. As standard, batch fire sequencing is "random" at the change from cranking
mode to run mode. This setting forces the sequence to always start on the same "trigger" on each
startup. This can help if you are running batch fire injection and you find the engine runs differently
from startup to startup.
On an engine running wasted spark, the trigger numbers start at one and count up to half the
number of cylinders, with trigger 1 corresponding to the number one cylinder firing event. On an
engine running sequential coil on plug with batch fire injectors, the trigger numbers again start at 1
for the number one cylinder firing event and count up to the number of cylinders.
7.3 Ignition Settings
7.3.1 Dwell battery correction
The dwell battery correction/adjustment curve is a built-in curve to automatically apply greater spark
dwell at lower battery voltages. This is required for inductive ignition systems - more time is required
to charge the coil with less voltage. The default curve as shown is suitable for most applications. Note
that it is centered on 14.4V with 100% - at this voltage the actual dwell time matches the dwell entered
on the ignition options page.
7.3.2 Dwell vs RPM
The Dwell vs. RPM curve is a feature intended to be used with Saab Tri-ionic ignitions only. These
require "Time After Spark " to be enabled. The dwell vs. RPM curve must also be turned on under
the Ignition Options / Wheel Decoder mode, as shown below:
7.3.3 Dwell Table
This table allows you to specify dwell (before battery voltage correction) as a function of RPM and
ignition load. This allows increasing dwell under boost, then backing it off at low load to reduce the
amount of heat put into the ignition system.
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7.3.4 Cold advance
The cold advance feature can be used to run more (or less) advance on a cold engine. When cold, an
engine typically requires more advance for normal operation. Conversely, many OEMs are reported
to retard timing during warmup to more quickly bring the catalyst up to operating temperature. This
setting can be adjusted either way.
Ensure that the advance figure in the highest temperature point is zero; this will allow the spark
timing to follow the advance table when warmed up.
7.3.5 MAT based timing retard
High inlet air temperatures (MAT) can make an engine more prone to knock; this is especially the case
on boosted engines where prolonged periods of hard driving or idling in high ambient air temperatures
can have a significant impact on MAT. This feature allows the timing to be retarded at higher MAT
readings for greater engine safety.
Ensure that the retard figure at normal temperatures is zero, this will allow the spark timing to
follow the advance table during normal operation.
7.3.6 Noise filtering
The noise filtering menu allows the MS3-Pro to detect and ignore pulses on the crank and cam
position inputs caused by electrical noise.
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In the simplest form of a fuel-only controller with a tach signal from the coil negative, the "ringing"
of the coil may cause apparent rpm spikes. This will cause additional fuel to be injected on each of
these noise pulses and show up as a falsely high rpm. It will likely be irritating, but no major problems
are likely.
On an install controlling ignition, it is a different matter. In the simple distributor install with a
simple trigger arrangement (1 pulse per ignition event like in a normal distributor), the noise will cause
a misfire probably on that one event. On a multi-toothed wheel, the noise is likely to cause a loss of
sync with the wheel, and spark will be lost for 360 or even 720 degrees of engine rotation before the
re-synchronization occurs.
So, the tach input is critical to ECU operation, it is important to reduce or eliminate that noise.
Hardware is your first line of defense. Here are some tips on setting up hardware to keep out noise:
• Set the sensor gap to an appropriate level. Most sensors work with a gap about the thickness
of a normal business card.
• Use shielded wire, like in our standard wiring harness. Ground the shield at only one end - a
shield grounded at both ends can carry current, and induce noise in the signal.
• Route the signal wire away from any electrical noise sources, such as ignition coils, spark plug
wires, and the alternator or starter.
• Ensure that the MS3-Pro has a clean ground to the engine block, cylinder head, or negative
battery terminal.
• VR sensors need to be connected to the positive and negative signal wires. Hall effect or optical
sensors should be grounded to the MS3-Pro sensor ground.
With the hardware well defended against noise, the second line of defense is to set up the ECU to
read the sensors correctly and reject noise. The first setting is the ignition input capture is correct,
as covered in section 5. For example, the VR signal below has one stable and one unstable edge. It
needs to be set to triggering on Rising Edge.
Setting to Falling Edge would result in an unstable signal - you’ll see this as timing scatter and the
RPM bouncing around. And this is with a fairly clean signal, which the processor would see like this
if triggering on the correct edge:
If the wiring or sensor isn’t perfect, and the signal becomes noisy, the CPU will see a signal like
this instead:
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There are several strategies the MS3-Pro has to filter this out, which you enable from the Noise
Filtering screen.
• Noise filter period - this sets a minimum pulse time to ignore, measured in clock cycles. Each
clock cycle is 0.02 microseconds, so a value of 4 corresponds to 0.08 microseconds. It can filter
out very short noise spikes, like this:
Any pulse shorter than this time is considered to be noise and thrown out.
Primary Tach settings apply to the crankshaft position (CKP) input.
• Noise filter enabled - enables noise filter curve on primary/crank tach input. This sets a minimum pulse time versus RPM curve (the noise filter curve to the right)
The noise filter works on the principle that the noise is likely to be of short duration, far shorter than a
genuine tooth. If all inputs conditioners are setup correctly, we should be able to detect this condition
by measuring the width of the input pulse. A "long" pulse is real, a "short" pulse is noise. The width
can vary with RPM, so the curve allows you to set a minimum time.
• Tach period rejection - ignores pulses shorter than time/percentage
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This is a different approach: It ignores any pulse that comes in within either a timeframe or percent
of the spacing between the tach pulses. This goes off the timing of the pulse, rather than the length.
Note that the spacing used is between the smallest teeth, so this method works best on wheels
where most of the pulses are a similar distance apart. Modes like the Subaru 6/7 have several closely
spaced pulses (at least on the cam wheel), rendering this method less effective.
• Tach interrupt masking - turns off input pin so pulses are not seen at all for time/percentage
This setting is similar to tach period rejection. However, instead of sensing and rejecting pulses in
the rejection time, this setting outright turns off the interrupt - it actively stops the ECU from listening
during the rejection wheel.
• Time(ms) - time period to ignore for interrupt masking or period rejection.
• Percentage - percentage of "tach interval" to ignore.
Secondary Tach settings apply to the camshaft position (CMP) input.
• Noise filter enabled - enables noise filter time on secondary/cam tach input.
• Noise filter time period - pulses shorter than this are treated as noise. Used instead of the
noise filter curve.
• Tach period rejection - ignores pulses shorter than time/percentage
• Tach interrupt masking - turns off input pin so pulses are not seen at all for time/percentage
• Time(ms) - time period to ignore.
• Percentage - percentage of "tach interval" to ignore.
7.3.6.1 Examples These should be taken as a starting point and will often need install specific
tuning.
• Coil negative triggering for a fuel-only install. This requires noise filtering to eliminate the
effects of coil ringing. A typical setting would be to enable crank tach period masking at 2ms
and 30%.
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• Distributor type pickup, such as HEI, TFI, or EDIS (although the last is not a distributor, the
MS3-Pro will see a similar signal.). Noise filtering is often useful here. A typical setting would
be crank tach period masking with 1ms and 30%.
• Wheel decoder and other more advanced installs. Noise filtering may be useful on some
installs. Due to the multi-toothed input signal the rejection time periods need to be set far
smaller. e.g. on a V8 with distributor at 6000rpm, the time between tach pulses is 5ms. A 36-1
wheel on the same engine gives a pulse every 0.6ms (600us). Using too large a filter time will
filter out the real signal.
7.3.7 Knock sensor settings
Note: While this is a fairly good setup as far as knock sensing goes in a race ECU, getting
OEM like levels of knock protection generally requires grenading a few motors on the dyno to
get it dialed in perfectly. This can provide an extra layer of protection, but never use knock
sensing as your only spark tuning tool!
Spark knock is the sound of abnormal combustion in an engine. Once combustion in a sparkignition internal combustion engine is initiated by a spark, the flame front is designed to spread
from the spark plug and travel across the combustion chamber rapidly and smoothly. As the flame
front propagates across the chamber, the remaining unburnt air-fuel mixture can ignite spontaneously
(auto-ignites) before the flame front arrives, due to the increasing pressure and temperature in the
combustion chamber. When this occurs, there is a sudden jump in the pressure in the cylinder. This
causes in the characteristic knocking or pinging sound. It is most common at low-mid rpms and high
load, such as ascending a hill in too high a gear.
Prolonged heavy knock is likely to cause severe and permanent engine damage and must
be avoided.
It is a common misconception that engines make most torque just before knock. In reality, there
isn’t much of a connection between the knock threshold and the timing that makes best torque. A
knock resistant engine may start losing power well before the onset of knock, while a knock limited
engine may have the point where it makes best power past the knock threshold (and not safe to reach
without higher octane fuel) Ideally, set timing on a dyno to achieve maximum brake torque (MBT)
timing. Even with a well tuned engine, factors such as fuel octane, intake air temperature, coolant
temperature, engine age and condition, air/fuel ratios, air density, altitude and humidity and others
can push the engine from a safe condition to borderline knock or worse. The knock control system is
a safety measure designed to retard timing under these conditions and safeguard the engine.
The MS3-Pro contains an internal module that can process one or two knock sensors. It also
allows input from an external module that gives an on/off, “knock” or “no knock” signal. The knock
sensor inputs use dedicated wires intended for connecting directly to a knock sensor. External modules would use the digital input wires instead.
There are two main types of knock sensor. Resonant and wideband sensors. The resonant
sensor is tuned to a particular frequency and is only likely to work on an engine with a very similar
bore size. (Bore size determines "ping" frequency.) The wideband sensors give a lower voltage output
but operate over a wider frequency range, and can usually be applied to different engines.
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The GM resonant knock sensor pictured above is tuned to a specify frequency, like a tuning fork.
When this frequency is applied to the sensor (through its connection to the engine), a piezoelectric
crystal inside the sensor generates a small voltage (~1 volt), much like a microphone. As an example,
some Corvette knock sensors (GM PN 1997562, 1997699, or Standard Motor Products KS45, KS46,
KS49, or KS117) have a design frequency of 5200 Hz, and they produce a signal between 4800 Hz
and 5600 Hz.
Most Bosch sensors with a hole through the center are wideband knock sensors, adaptable to
many engine types.
The sensor should be mounted near the top of the engine block, as close to the center as practical.
Do not mount it close to noisy components such as the fuel pump or cam shaft lifters. Mounting the
knock sensor in the cylinder head is not a good idea because of valve train noise. Finding a suitable
location of the sensor is crucial. Wherever possible, use the location specified by the manufacturer
for that engine family.
Ideally, you will be able to find a suitable threaded hole in your block to which you can mount the
sensor. If not, an alternative is to drill and tap the block, or thread a steel adapter to accommodate
the sensor on one end and a stub with the thread to match those in an existing pre tapped boss in
your block. Note that it may be necessary to change the sensor location if you cannot isolate engine
noise while allowing MegaSquirt to identify knock.
If you choose to drill and tap your block, choose a thick area of the block with a boss that is at
least ¿" (19 mm) thick. Drill a ¡" (13mm) hole. The hole should be 0.500" to 0.625" (13 mm to 16 mm)
deep. Make absolutely sure that it is safe to drill a hole this size - a poorly placed hole can trash
the engine block.
The GM knock sensors have a 3/8" NPT thread. Tap the hole with a 9/16" UNF starter tap. Go in
4 turns of the tap to begin with, clean out the chips and try the sensor for fit. Keep tapping one turn
at a time until the sensor threads in 4 to 5 turns with hand pressure. Stop tapping when the sensor
will screw into the hole 6 to 7 threads with a wrench. Note that the thread on the knock sensor is a
tapered thread.
The Bosch sensor can be more simply attached by bolting it to the block. It uses a standard EV1
style injector connector.
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The knock sensor settings screen lets you adjust how the MS3-Pro handles knock input.
7.3.7.1 Knock sensor settings
• Knock control: Allows you to change the way the MS3-Pro applies timing retard.
– Disabled: do not use knock feedback for ignition advance control
– Safe Mode: use knock retard, but keep the advance below that which caused knock. This
backs the advance 1 small step back and leaves it at that until TPS or MAP changes - or
knock comes back. This is "safe mode" scheme is the safest thing for a DIY set-up.
– Aggressive Mode: use knock retard, but keep advance at threshold of knock occurring.
That is, the program advances (up to the timing table value) if it doesn’t see knock, and
retards if does see knock. The difference from safe mode is that the timing can be advance
all the way to the table value after knock, not just up to one step below knock. This may
result in the knock returning, in which case the timing is retarded again, then advanced
slowly, and so on. This approach is also called closed loop knock control.
• Input type:
– On/Off: basic on/off "knock" or "no-knock" external input.
– Analogue: external analogue input proportional to knock signal level
– Internal: internal knock module.
• Input pin (only for on/off) Which input pin the external module is connected to.
• Knock Indicated By (only for On/off) The logic input level. i.e. when set to "low" then a 0V
signal means there is knock. GM external knock modules fall into this categories.
• Pullup/down on input (only for On/off) Whether an internal pull-resistor should be applied.
When using the normal digital input modes, this should be set to “None.”
• Input pin (only for Analogue) Which analogue input pin the external module is connected to.
• Window Sample Type (only for Analogue) Either read single analogue value at end knock
window or peak detect.
• Window Output (only for Analogue) Optional digital output for knock window signal.
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7.3.7.2 Detection
• Knock Count (knocks): number of knock events detected before control is started
• Knock Ignored above MAP (kPa): no knock retard is implemented above this MAP
• RPM window low (rpm): knock control is implemented above this rpm
• RPM window high (rpm): knock control is implemented below this rpm. This upper limit is
desirable as valve train noise will typically mask out the knock sensor signal at higher rpms
which could cause false reports of knock.
7.3.7.3 Retarding
• Maximum Retard (deg): maximum total retard when knock occurs. This can be useful to
prevent timing from being excessively retarded (avoiding potential overheating issues) if the
senor malfunctions or there are other problems with the knock sensing system.
• Retard Check Time (sec): this is the time between knock retard corrections, allows short time
step to quickly retard.
• Retard Coarse Step Size (deg): ignition retard step size when 1st knock, make it large to
quickly retard the timing and stop knock.
• Retard Fine Step Size (deg): ignition retard step size when knock restarts after it had stopped.
7.3.7.4 Recovery
• Advance Check Time (sec): this is the time between knock advance corrections (I.e., timing
return to "normal")
• Advance Step Size (deg): ignition advance step size after knock has stopped.
• Recovery Advance (deg)): this is the change in table advance required to restart advance until
knock or reach table value (0 knock retard) process. This only applies in Safe Mode.
7.3.7.5 Knock input threshold For analogue and internal modes, this sets a threshold level. If the
measured knock signal exceeds the threshold, then the control system is started. This allows different
thresholds to be applied to match actual engine behavior. The curve will need to be set empirically by
examining datalogs of knock% when operating the engine under safe conditions.
7.3.8 Knock sensor parameters
This screen is used with the internal knock processing.
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• Bandpass frequency - this should be adjusted to suit the resonant frequency of you engine.
(Formulae exist on the web for estimating this frequency based on bore diameter.)
• Integrator time constant - internal setting to knock sensor chip. Default is 150us. A larger
number will reduce the output level and creates more filtering.
• Number of sensors - how many knock sensors are connected (1 or 2.)
• Monitor per cylinder - when sequential fuel or spark are in operation the code can determine which cylinder the knock signal applies to. This enables the individual cylinder data to be
recorded.
• Gain - compensate for sensor sensitivity and distance between cylinder and sensor.
• Sensor - pick which sensor to use for each cylinder.
Some engines have multiple knock sensors. In this case, you will usually want to pair the cylinder with
whichever sensor is nearest. For example, LS1 style engines use a pair of sensors in the valley which
are positioned to "listen" to four equally spaced cylinders each. i.e. the front sensor corresponds to
cylinders 1,2,3,4 and the rear sensor to cylinders 5,6,7,8.
7.3.9 Knock window settings
These are used with both internal and analog knock sensing modes.
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The upper chart sets the crank angle to start the knock window on the cylinder being monitored.
Positive is before TDC, negative is after TDC. The lower chart sets how many crank degrees the
knock window stays open for. The defaults reflect that knock events start around top dead center on
most engines.
7.3.10 Knock coolant scaling
This screen is used with both internal and analog knock sensing modes.
This allows increasing the knock threshold at low coolant temperatures. Many engines are noisy
during cold operating due to increased clearances. This would result in false knock reports if the
threshold was not raised at low temperatures. Ensure that the final row is 100% for a warmed up
engine.
7.3.11 Rotary settings
The MS3-Pro supports Wankel rotary engines with a leading and trailing spark plug split. Versions
supported include Mazda’s RX-7 FC, FD, and RX8 ignition types, as well as 3 and 4 rotor engines with
coil on plug. To enable this screen, “Engine Stroke” under Engine and Sequential Settings must be
set to Rotary.
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The “Allow negative split” setting lets you fire the trailing spark plugs before the leading (positive
split numbers have the trailing spark plugs fired after the leading). You can also set a separate dwell
time for the trailing coils. Note that all rotary modes have you set the number of injectors to the number
of primary injectors; a 2 rotor engine would have the number set to 2, even though there are a total of
four injectors, two primary and two secondary.
Here are the output modes available.
7.3.11.1 FC mode The second generation RX-7 used a logic level wasted spark coil for the leading
plugs and a coil that had a “coil select” mode for the trailing coil. FC mode requires setting “Number
of coils” to “wasted spark”, and uses this wiring.
Ignition wiring:
• Spark A Leading coil (IGt-L)
• Spark B Trailing coil (IGt-T)
• Spark C Trailing coil select
Fuel wiring:
• Inj A Front rotor primary injector
• Inj B Rear rotor primary injector
• Inj C Front rotor secondary injector
• Inj D Rear rotor secondary injector
7.3.11.2 FD mode The third generation RX-7 retains a wasted spark coil for the leading plugs, but
the trailing plugs are individual logic level coils. As with FC mode, “number of coils” needs to be set
to “wasted spark.”
Ignition wiring:
• Spark A Leading coil (IGt-L)
• Spark C Front trailing coil
• Spark D Rear trailing coil
Note that FD mode does not use spark B - this is done to match the RX8 mode. If you ever convert
to coil on plug, this means you only have to change one wire instead of three.
Fuel wiring:
• Inj A Front rotor primary injector
• Inj B Rear rotor primary injector
• Inj C Front rotor secondary injector
• Inj D Rear rotor secondary injector
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7.3.11.3 RX8 mode The RX8 mode is automatically enabled if you set the number of coils to “coil
on plug” and the number of rotors to 2.
Ignition wiring:
• Spark A Front Leading coil
• Spark B Rear Leading coil
• Spark C Front trailing coil
• Spark D Rear trailing coil
Fuel wiring:
• Inj A Front rotor primary injector
• Inj B Rear rotor primary injector
• Inj C Front rotor secondary injector
• Inj D Rear rotor secondary injector
7.3.11.4 3 rotor Using three rotors requires coil on plug ignition to be set.
Ignition wiring:
• Spark A Leading coil A
• Spark B Leading coil B
• Spark C Leading coil C
• Spark D Trailing coil A
• Spark E Trailing coil B
• Spark F Trailing coil C
Fuel wiring:
• Inj A Primary injector A
• Inj B Primary injector B
• Inj C Primary injector C
• Inj D Secondary injector A
• Inj E Secondary injector B
• Inj F Secondary injector C
The coils and injectors need to be wired in firing-order sequence. The outputs fire A,B,C,D,A....
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7.3.11.5 4 rotor As with 3 rotor mode, this requires enabling coil on plug ignition.
Ignition wiring:
• Spark A Leading coil A
• Spark B Leading coil B
• Spark C Leading coil C
• Spark D Leading coil D
• Spark E Trailing coil A
• Spark F Trailing coil B
• Spark G Trailing coil C
• Spark H Trailing coil D
Fuel wiring:
• Inj A Primary injector A
• Inj B Primary injector B
• Inj C Primary injector C
• Inj D Primary injector D
• Inj E Secondary injector A
• Inj F Secondary injector B
• Inj G Secondary injector C
• Inj H Secondary injector D
The coils and injectors need to be wired in firing-order sequence. The outputs fire A,B,C,D,A....
7.3.12 Rotary split table
This allows you to specify the split in degrees between leading and trailing sparks. Positive numbers
mean the trailing is later. Negative means that trailing is fired before leading.
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7.3.13 Cylinder trim tables
These tables are accessible if Spark Trim is set to On under Ignition Settings / Wheel Decoder.
Each screen has four mini spark tables which are added to or subtracted from the main ignition
table.
7.4 Startup / Idle
Section 5.4 covers the preliminary idle control setup. Section 6.3.6 covers many of the basics of the
MS3/Pro’s startup sequence, including the Cranking Pulse Width, Priming Pulse, Afterstart Enrichment, and Warmup Enrichment. Here, we’ll cover the startup and idle control that was not covered
there, and revisit a few settings in more detail.
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7.4.1 Cranking / startup settings
• Cranking RPM - On the initial start, the MS3-Pro will run in batch fire on the cranking pulse
width settings until RPM rises above this threshold, or if the RPM falls below this threshold
within 5 seconds of starting. Set this value higher than the engine can reach while being just
driven by the starter. The goal with this setting is to set it to a point where it will know the engine
is up and running once RPM goes over this value.
• Flood clear TPS - If the throttle position exceeds this value below cranking RPM, the MS3-Pro
will shut off the injectors because it will take this as a signal to clear a flooded engine.
• Batch fire during crank - If set to on, the MS3-Pro will fire all injectors every ignition event
during cranking. If set to off, the MS3-Pro will use sequential injection during cranking as soon
as it has established cylinder identification. This setting is grayed out if the engine is set to
batch fire as it will use batch firing on every ignition event in this case. Using batch fire during
cranking can allow more fuel to be injected in cold climates - the maximum cranking pulse widht
is approximately 65 ms, so injecting fuel more often can allow for more fuel during startup.
• Cranking taper curve - This curve allows for the ECU to vary the pulse width while cranking,
generally used to allow a large initial fuel shot that tapers off. This can make for easier startup
but is a bit more complex to tune.
• Cranking taper curve units - The taper curve can either use time or ignition events to change
how it adjusts fuel.
• Cranking fuel pulse rate - When using batch fired cranking, you can inject fuel every ignition event or every other ignition event. Every other ignition event can give better hot starting
behavior on engines with more than 8 cylinders.
• Blended cranking curves - Allows using a blend curve to blend between two cranking pulse
width tables. This is most commonly used with flex fuel engines.
• Priming pulse delay - Allows you to delay the priming pulse instead of firing it as soon as the
key is turned on.
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• Ignore MAT correction during ASE - This setting allows the MS3-Pro to override the air temperature correction while afterstart enrichment is active. If this is turned on, MAT correction will
be set to 100% until the ASE time is complete. This is useful if the IAT sensor is in the intake
manifold and absorbs heat from the manifold.
• ASE count units - You may set the afterstart enrichment to be based on either time or engine
cycles.
7.4.2 Cranking Taper Curve
This curve provides a multiplier for the pulse width during cranking, with 100% being to use the
cranking pulse width curve unchanged. The curve will repeat itself after reaching the end point. On
some engines, an initial spike of fuel followed by pulling fuel can lead to better startup performance.
7.4.3 Priming Pulse 2 through Warmup Enrichment 2
These are used in dual fuel mode or a blend curve (see Table Choices) if running on an alternate
fuel, as different fuels have different behavior when cold. An extreme case is CNG (compressed
natural gas), which has almost no tendency to stick to the intake walls even on the coldest engine.
This means an engine running CNG will require very little warmup or afterstart enrichment. E85 often
requires different cranking pulses from gasoline as well, both because it has a lower air/fuel ratio and
because it is more likely to stick to a cold intake manifold.
7.4.4 Idle control
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The MS3-Pro firmware has several methods for controlling idle speed, besides the “not run any
sort of ECU control, and just use a set screw to hold the throttle open” method. They were introduced
in section 5.4, but we will cover them again in more detail.
The current firmware allows you to specify the valve type separately from open vs closed loop
operation.
• Idle valve type
– None: The MS3-Pro does not control idle speed.
– On/Off Valve: The valve is a two wire solenoid that can only turn on or off with no in between
positions.
– PWM valve: A solenoid type valve where the amount of opening is controlled by the output
duty cycle.
– Stepper valve: This uses a rotating motor to move a pintle. The motor takes a discrete step
every time one of the wires is pulsed.
• Algorithm
– Open-loop (warmup): The MS3-Pro commands how far to open the valve as a function of
coolant temperature. Note that on/off valves are always open loop, so this setting is grayed
out when an on/off valve is selected.
– Closed-loop: The MS3-Pro adjusts the idle valve opening to match an RPM target.
The different valve types use different settings, described in detail below.
7.4.4.1 On/Off Valve
• Fast Idle Temperature - The MS3-Pro will energize the on/off valve until the engine reaches
this coolant temperature.
• Hysteresis - The amount of temperature drop below the fast idle temperature needed for the
on/off valve to turn back on. This prevents the valve from toggling on and off rapidly when the
engine is right at the fast idle temperature.
7.4.4.2 Stepper valve settings
• Time Step Size - This is the number of milliseconds the firmware will wait between each step if
the idle valve moves more than one step. If a valve does not move reliably, this setting should
be increased. Setting this valve too high will make the valve move slowly.
• Initial Time Step Size - This is the number of milliseconds for the first step. It is often set longer
than the other steps to help overcome friction.
• Minimum # of steps to move - This is the minimum number of steps the controlling piece of
code has to command before the code that moves the valve will actually try to move the valve.
We’ve found some stepper valves, particularly used ones on older cars, may stick if commanded
to move fewer than 5 to 8 steps.
• Homing steps - This is the number of steps the valve will move (in the homing direction) on
boot so that the rest of the code can rely on the start position being accurate. After homing, the
IAC valve will then move to the number specified in the Cranking Steps.
• Homing direction - You can set the valve to go through its homing routine by either opening or
closing.
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• Wide Open Steps - If the homing direction is set to open, this number defines the amount of
steps from the closed position to wide open.
• Crank-to-Run Taper Time - This is the amount of time the IAC valve uses to transition after
starting from its crank position to its running position.
• Power between steps
– Moving only: Power is turned off in between steps. Do not use if the valve freewheels when
unplugged.
– Hold current: Applies partial current in between steps.
– Always on: Leaves the valve at full power between steps. This produces the most heat but
will prevent a 4 wire stepper from moving when not commanded. Use this if the valve spins
with almost no resistance when unplugged.
7.4.4.3 PWM idle valve settings
• Crank-to-Run Taper Time - This is the amount of time the IAC valve uses to transition after
starting from its crank position to its running position.
• Valve Mode - Normal mode is off at 0% duty cycle, inverted mode is off at 100% duty cycle. As
the name implies, most valves use normal mode. If you’ve found you accidentally wired up a 3
wire IAC valve backwards, just flip this setting.
• Run valve before start - If set to on, the valve is energized with the key on and engine off. This
allows for slightly faster starting, but some PWM valves may make an objectionable amount of
noise before starting. Turning this off will prevent the valve from making noise with the engine
off, but may produce a small delay in starting.
• Output Port - Allows you to pick which output wires are used. In 3 wire mode, this is for the coil
that opens the valve.
• 3 wire mode - Used with 3 wire rotary IAC valves, common in Denso and Bosch applications.
This may be left off or used to specify the connection used for the coil that closes the valves.
• Valve Frequency Selection - Select a frequency from the list. Different valves operate best on
different frequencies.
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7.4.5 Idle Cranking Duty / Steps
This screen gives how much IAC valve opening to apply when the engine is cranking as a function
of temperature. A larger value means more opening. PWM valves go from zero to 100% duty, while
stepper valves allow specifying how many steps to use.
7.4.6 Idle Warmup Duty / Steps
This sets the position of the IAC valve as a function of temperature when the engine is running
when using open loop mode.
7.4.7 Closed loop idle settings
Closed loop idle lets the MS3-Pro target a set idle speed instead of opening the IAC valve a set
amount. This is used for compensating for changing engine loads. It should not be used to fix a
roving or hunting idle at steady load - you need to get the idle tuned so it is stable in warmup mode
under constant load first, if you find the idle is hunting.
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First, here are what the settings do.
The Closed Loop Idle Valve settings tell the MS3-Pro what range of valve opening to use and
where to set the valve when closed loop idle engages. Note that this screen will change between
“steps” or “duty” depending on whether you have enabled a stepper or PWM idle control valve.
• Idle Valve Minimum Duty or Minimum Steps - This specifies the lowest duty or number of
steps, below which changes in the opening position no longer affect RPM. The closed loop
control will not set the IAC valve to a lower number.
• Idle Valve Maximum Duty or Maximum Steps - This specifies the highest IAC position beyond
which further changes do not affect RPM. Note that intentionally setting this low can make the
closed loop idle a bit less sensitive and more stable.
• Dashpot Adder - The MS3-Pro will disengage the closed loop idle based on TPS or other
criteria. Once the TPS reading falls below the Idle Activation TPS threshold, the MS3-Pro will
add this amount to the current IAC valve opening to prevent the RPM from falling too quickly
and making the engine stall.
• Use last value or table - If “Use last value” is selected, the MS3-Pro will start with the value it
last used to obtain the target RPM when closed loop idle re-engages. If set to “use table,” when
the closed loop idle engages, it will select the initial idle opening from the Closed Loop Idle Initial
Value table.
• Use CLT or MAT in table lookup - This specifies if the initial value table uses coolant or manifold
air temperature to determine the initial value.
• Close delay - This setting controls how long in seconds the valve takes to go to the closed
position after the throttle is pressed. A setting of 0 seconds means do not close the valve.
• Leave Valve Closed Above (rpm) - On throttle lift, leave the idle valve closed above this RPM.
Note: This setting is only necessary if a close delay is set since otherwise, the valve does not
close when the throttle is pressed.
• For this number of seconds - This setting re-opens the idle valve after the number of seconds
set on throttle lift/shift. For example, if the throttle is lifted, and RPM is above the Leave Valve
Closed Above setting, the valve will stay closed until the value set for this setting expires, then
the valve will open to the previous learned value plus the dashpot adder. The purpose of this
setting in combination of with the Leave Valve Closed Above setting is to keep the valve closed
when shifting gears, but open it on longer overrun events.
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Closed loop idle PID gains are used to tune the response of the valve. We’ll go over the tuning
process after covering the remaining settings.
• Tuning Mode - In Basic, the P and I terms are set to 100, the D term is set to 0, and the slider
is the only adjustment. In Advanced, you can adjust the gains separately, and then they can all
be scaled with the slider.
• Proportional Gain This setting controls the Proportional Gain of the PID algorithm. Setting this
higher will result in a larger immediate response to changes in RPM. Setting this too high can
result in unwanted oscillation of RPM.
• Integral Gain This setting controls the Integral Gain of the PID algorithm. This is the PID setting
used to actually make the RPM meet the target RPM. Setting it too low will cause the RPM to
never reach the target. Setting this value too high will result in unwanted oscillation of RPM.
• Derivative Gain This setting controls the Derivative Gain of the PID algorithm. It can be used
to help dampen the effects of the Proportional and Integral settings. It is usually not necessary
for good control of idle speed. It is recommended that this is left at 0%.
Closed Loop Idle PID Delays and Behavior - These settings cover more about how the engine reacts
to a given amount of valve opening. The code has two adjustments, a sensitivity slider that affects
response with a single adjustment, and individual PID gain adjustments for engines that need more
detailed changes.
• PID delay - This is how long in seconds all other conditions for entering PID control must be
met for before the code will engage PID control. Set this as low as possible without being below
what is normal RPMdot jitter with the engine RPM not changing. Typical values will be between
50 and 75 RPM/sec.
• Crank to run taper - How long after starting the code will wait to engage PID control.
• PID ramp to target time - This setting controls how long after the PID control algorithm engages
the code will take to reach the target. The code starts with an RPM target of whatever the current
RPM may be, and then slowly over the ramp to target seconds reduces the target to the value
set using the target RPM curve. This can be used to help larger P-values be used, making it
easier to tune PID to catch sudden drops in idle speed.
• PID Control Interval - This controls how often the PID control code runs. Setting this too high
will make the code respond too slowly to sudden changes in load, possibly allowing the engine
to stall. Setting it too low will make the engine unstable and likely to
• PID disable RPMdot - This setting was added specifically for those who sometimes engage
the clutch while rolling to a stop after letting the PID code engage. Set this setting as low as
possible so that when RPM suddenly jumps when the clutch is engaged, PID is disabled and
does not try to close the valve due to the RPM suddenly going up.
Closed loop idle PID activation settings specify what conditions should be used to activate closed
loop idle control.
• Use VSS to activate PID - This setting controls whether the PID lockout settings (detailed
later) are used to activate idle speed control, or if VSS going to 0 MPH/KPH is used. If set to
“standard,” it will use the RPM range to determine if it should be using PID control. If set to “Use
VSS,” it will only engage closed loop idle when speed is below the minimum.
• Minimum VSS1 - Above this speed, closed loop idle is turned off.
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• Idle Activation TPS threshold - This setting is the throttle position below which the PID algorithm is engaged. It is used in conjunction with the RPM adder to determine whether or not to
engage PID control of the idle valve. This should be set as low as possible to avoid the idle
valve closing when the throttle is pressed.
• RPMdot threshold - This is a maximum RPM change in RPM per second. Above this rate,
the MS3-Pro will expect the car to be in engine braking and not activate closed loop. Set this
as low as possible without being below what is normal RPMdot jitter with the engine RPM not
changing. Typical values will be between 50 and 75 RPM/sec. This may look similar to “PID
Disable RPMdot.” However, this setting is used to allow the MS3-Pro to enter closed loop idle,
while PID disable RPMdot is used to deactivate closed loop idle.
• Max decel load - This setting controls the kPa below which the PID lockout detection code is
disabled. This should be set to a kPa just under the lowest kPa that is seen during a fast idle.
7.4.7.1 Tuning closed loop idle Before trying to tune closed loop idle speed control, be sure to try
tuning warmup only idle speed control. With warmup only control, a higher step-count or duty should
yield higher RPM. Make sure that this is the case, and that smooth idle speed can be attained with
warmup only before moving on to closed loop control.
There are two main things to tune when tuning closed-loop idle speed control:
• PID gains
• Conditions for entering PID control
We recommend tuning these in stages. For example, PID cannot be tuned if the code is never
entering the PID loop. Because of this, it is a good idea to start by tuning the conditions for entering
PID control, then come back and tune the PID gains.
These settings include:
• Use VSS to activate PID - This takes the place of the PID lockout settings. Turning this on will
make it so that the PID loop activates after the vehicle speed comes to zero MPH/KPH.
• Idle Activation TPS threshold - Set as low as possible. If the TPS has a bit of noise, set it to
around 1%; otherwise set it to 0.3%-0.5%.
• PID delay - This should be set so that the RPM dropping on throttle lift can come to a rest
slightly higher than the target RPM, and become stable there. Between three and five seconds
normally works the best.
• Crank to Run Taper - This setting controls how long after starting the code will delay before
entering PID. Between three and five seconds works well for this setting.
• RPMdot threshold - This is the first of the PID lockout detection settings. Use this setting so that
the code can tell the difference between decelerating with closed throttle (engine braking) and
sitting at one RPM. Set this as low as possible without being below what is normal RPMdot jitter
with the engine RPM not changing. Typical values will be between 50 and 75 RPM/sec.
• Max decel load - This is the second PID lockout detection setting. The code assumes that if
MAP is lower than this setting, the driver must be decelerating, and not "locked out" of the PID
loop. Set this to a value just under the load seen with an idle slightly higher than the current
target RPM + the Idle Activation RPM Adder. This can be done by temporarily switching to
warmup-only mode or idle test mode, and setting the valve position manually.
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• PID disable RPMdot - A good value for this setting will typically be in the 200-400 RPM/sec
range. If the engine speed suddenly accelerates with no throttle input (like if the clutch is engaged while the car is rolling and in gear), it must accelerate at a rate greater than this setting
before the PID code will be disengaged. Setting this value too high can lead to stalls after
engaging the clutch in this manner.
To tell whether the code is entering PID idle control, use the "CL Idle" indicator in TunerStudio. If the
current gauge cluster in TunerStudio does not include this indicator, temporarily switch to a cluster
that does.
Most modern OEM cars enter idle speed regulation in a very similar manner. The MS3 idle speed
control algorithm was emulates this behavior. The sequence of events that the code was designed to
follow are listed below:
1. Throttle Lift - On throttle lift, the code opens the valve to the value learned in the last iteration
of the PID loop (or the initial value table) + the dashpot adder. The logic here is that the last
learned value should result in an RPM close to the target RPM. The dashpot adder is added so
that when RPM settles, it settles to an RPM slightly higher than the target. This is in case the air
conditioning was turned on or IAT increased or anything else that might make RPM lower than
the last time the PID code ran.
2. RPM settles - After throttle lift, eventually the clutch is pushed in and RPM drops to wherever
it will settle given the learned value + the dashpot adder. Hopefully, the idle has settled to an
RPM that is less than the commanded target + the Idle Activation RPM adder. If so, then the
code will wait for the amount of time specified by the PID delay, and then enter PID control. If
RPM settles above the commanded target + Idle Activation RPM adder, the code then starts
checking the PID lockout detection conditions. Assuming those conditions are met, the code
will still enter the PID loop after the amount of time specified by the PID delay.
3. PID control activates, RPM starts dropping to target - After the PID delay expires, the PID code
will be activated. RPM will slowly drop to the target over the number of seconds specified by the
PID ramp to target time.
4. Normal idle speed reached - RPM reaches the commanded target. PID continues regulating
RPM until the throttle is pressed.
Once the code is reliably entering PID on every throttle lift, it is time to actually tune the PID code to
reach and hold the RPM target. The settings that are associated with or affect the operation of the
PID algorithm are listed below:
• Idle Open Duty/steps and Idle Valve closed duty/steps - These should be set to the minimum
and maximum values that should be used during PID loop and driving operation. In addition,
having these set further apart results in the PID loop being more sensitive (making changes to
the output given much smaller changes in input).
• Min duty/steps for PID - This is the lowest duty/number of steps that the PID loop is allowed to
command. Set this low enough to result in an RPM slightly lower than the lowest target RPM.
• RPM with valve open/closed - These should be set to the RPM with the valve closed and the
RPM with the valve opened respectively. If using these settings makes the code unresponsive
to changes in idle speed, the upper RPM value can be set lower.
• PID Control Interval - This controls how often the PID code runs. Setting this too high can result
in sluggish response to sudden changes in load, such as the Air Conditioning being turned on.
Setting it too low can result in the loop being overly sensitive to RPM changes. Typically 100ms
works well.
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• PID controller gains - These control the actual response of the code to changes in RPM, as well
as how well the code will reach the target. Tips for tuning these are listed below.
In Basic mode, simply adjust the slider, starting with a low value and increasing it until the engine can
react fast enough to any load placed on it to avoid stalling or an unacceptable RPM dip.
The following basic steps should be used for tuning the PID controller gains in advanced mode:
1. Zero all the gains - Set all the gains to 0%. This is so that the effects of tuning the I-term in the
next step are not confused with the effects of any other setting.
2. Tune the Integral (I) gain - The Integral gain is the only term that controls whether the code
actually reaches its target. Higher values for Integral gain will result in the code being able to
get closer to the commanded target; however, a value that is too high will result in oscillation.
The easiest way to determine a good value for the I term is to keep increasing it until oscillation
occurs, then slightly lower it. If this value is increased to 200% without reaching a point where
oscillation occurs, then the RPM with valve opened setting can be decreased as far as necessary, and the open duty/steps setting and closed duty/steps setting can be made further apart
to make the PID loop more sensitive.
3. Tune the Proportional (P) gain - After tuning the I gain so that the RPM reaches the commanded
target without oscillation, the P gain can be tuned. The best way to tune this is to set it as high
as possible without getting any oscillation. After setting this, try turning on the air conditioning
or other accessories that normally lower RPM or increase load. When these accessories are
turned on, the RPM should dip a bit, then recover (the valve position should increase significantly). Using longer PID ramp to target times can also make it so that when the PID algorithm
engages, a higher P gain can be set without causing oscillation.
4. Tune the Derivative (D) gain - For most users, use of the D gain should not be necessary. It
substantially dampens the response of the loop.
Some final tips:
• Idle Fuel Tuning - Before even attempting to tune Closed-loop Idle speed control, tune the area
around idle so that if RPM goes up or down or load goes up or down, the AFR stays close to
the same value. Changing AFR can affect idle speed, which can then cause the PID code to try
to correct, getting into an unrecoverable oscillation.
• Idle Advance - The idle advance feature can be used to help "catch" the idle in situations where
heavy load is suddenly added while the engine is idling. It is recommended that the advance
is increased with increasing load, and decreased with decreasing load. This way, when the air
conditioning or electric fan are turned on, the sudden increase in load causes a corresponding
increase in timing which generates more power. Also, this feature can be used so that on idle
without load, slightly less than what would normally be considered "optimal" timing can be used.
This causes the idle valve to need to open further to keep a particular idle speed. Then when
sudden load is added, the timing increases and the valve position does not have to change as
much to cope with the sudden load increase.
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7.4.8 Closed loop idle target curve
This screen is used when running closed loop idle. It lets you specify the target RPM as a function
of coolant temperature.
7.4.9 Closed loop idle initial values
If you are using closed loop idle with the initial value table selected, the MS3-Pro uses this to look
up the initial duty cycle when closed loop idle control engages. The X-axis specifies what target RPM,
and the Y-axis is either coolant or air temperature, as determined by the closed loop settings screen.
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7.4.10 PWM Idle voltage compensation
This screen is available when using PWM warmup or closed loop idle. PWM valves, particularly
the two wire sort, change how far they open when the battery voltage changes. This number is added
to (or subtracted from, in the case of negative numbers) the duty cycle at the specified battery voltage.
Three wire PWM valves are less likely to need this.
7.4.11 Air conditioning idle up
The MS3-Pro can control the air conditioning and increase the idle speed when the air conditioning
is active.
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• A/C idleup on - Allows the MS3-Pro to control the A/C or increase idle speed when the A/C is
on.
• Idle-up output - This uses an output pin to activate the A/C compressor and/or condenser fan.
• Idle-up input - This is the input used to tell the MS3-Pro that the air conditioning is on or needs
to be turned on.
• Input Polarity
– Normal: The A/C switch grounds the ECU input to trigger the A/C.
– Inverted: The A/C switch sends 12 volts to the ECU to trigger the A/C.
• Idle-up Delay - The amount of time between receiving a signal on the idleup input and increasing the idle valve opening.
• Idle-up min RPM - The lowest RPM where the A/C can run. If the RPM falls below this point,
the A/C output is turned off.
• Compressor delay since last on - The minimum amount of time between turning the idleup
output off and turning it back on. Use this to prevent excessively rapid cycling of the compressor.
• Idle-up duty / idle-up steps - The amount to increase the idle valve opening when the A/C is
on.
• Idleup target RPM adder - You can either set this to zero to make the MS3-Pro hold a constant
RPM when the A/C engages, or use this to increase the RPM to better drive the compressor.
This feature requires closed loop idle to be on.
• Idleup CL load allowance - The engine may be under more load when decelerating with the
A/C on. This number is added to the PID lockout max decel load when the idleup input is on.
• TPS shutoff - The MS3-Pro turns off the A/C output above this TPS opening value.
• TPS hysteresis - Once the TPS based A/C shutoff has engaged, the TPS needs to fall this
amount below the TPS shutoff value to turn the A/C back on.
• VSS shutoff - Allows you to specify a speed above which the MS3-Pro turns off the A/C.
• VSS hysteresis - Once the VSS based A/C shutoff has engaged, the speed needs to fall this
amount below the VSS shutoff value to turn the A/C back on.
7.4.12 Idle advance settings
The Idle Advance feature is useful to fine-tune ignition timing at idle. It is particularly useful to help
catch sudden load increases on the engine at idle by increasing timing when load increases to help
the engine generate more power, keeping RPM from dropping severely.
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• Idle advance on - Enables or disables this feature.
• Idle RPM timing correction - Setting this to on allows the MS3-Pro to use the Idle RPM Timing
Correction curve to add or subtract timing based on how far away the idle speed is from the
target speed.
• TPS is below (%) - The TPS must be below this value before idle advance will engage.
• and RPM is below (rpm) - The RPM must also be below this value before idle advance will
engage.
• and load is above (%) - The engine load must also be above this value before idle advance will
engage.
• and CLT is above (degrees) - The engine coolant temperature must also be above this value
before idle advance will engage.
• and after delay (sec) - All the other conditions must be met for this amount of time before idle
advance will engage.
• Idle Advance Timing curve - This is a four-point curve with Load as the X-axis and timing as
the Y-axis. This curve determines the actual timing once the idle advance feature has engaged.
7.4.12.1 Idle advance tuning There are two main types of settings to tune for the Idle advance
feature:
• Idle Advance engagement settings - These settings control the conditions under which Idle
Advance will engage.
• Idle Advance Timing curve - This curve controls the actual ignition timing once all the Idle Advance engagement conditions have been met.
7.4.12.2 Tuning Idle Advance Engagement Settings The Idle Advance engagement settings
should be set so that idle advance will engage in roughly the same conditions that occur during
normal, warmed-up idle.
Settings recommendations:
• TPS is below - This setting should be set as low as possible. Typically settings between 0.5%
and 1% should be used. If numbers that are too low are used, then idle advance may not
engage if there is some play in the throttle body or there are minor electrical fluctuations that
cause the closed TPS % to vary. If numbers that are too high are used, then idle advance may
engage at undesirable times.
• and RPM is below - This setting should typically be set just above the desired idle RPM, and
below the lowest RPM at which the driver normally drives in gear. For example, if the desired
idle RPM is 800, then a good value for this setting is 1000.
• and load is above - This setting should be set just below the load value seen during a normal
idle with no load on the engine.
• and CLT is above - This setting should be set to the temperature at which the engine idle
characteristics no longer change. Generally this is when the engine is fully warm.
• and after delay - This setting should be set to a value that is long enough for the engine RPM
and load to become stable before idle advance engages.
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7.4.12.3 Tuning Idle Advance Timing In general, the most stable idle is reached by decreasing
the idle timing, and increasing the amount of air entering the engine (using an idle air valve or similar).
As such, the idle advance timing should be as low as possible while retaining a smooth idle. Since
less timing is used during normal idle conditions, as load increase, the timing should also increase to
counteract RPM decrease when the load increases.
7.4.13 Idle RPM timing correction curve
This screen is available when you have enabled closed loop idle and Idle RPM Timing Correction.
The RPM delta number is the difference between the target RPM and the actual RPM. This curve is
added to the ignition advance, allowing you to add more timing if the RPM is below your target idle,
or pull timing if the RPM goes over the target number.
7.4.14 Idle VE settings
The idle VE table is similar to the idle advance table, letting you specify a small VE table specifically
for idle. This can avoid tying up multiple rows in the VE table strictly for idle tuning.
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• Idle VE on - Setting this to On enables using the idle VE table, while setting this to off uses the
regular VE table at idle.
• PID idle activates - Setting this to “Use PID idle activation” activates the idle VE table when in
closed loop idle. Setting this to “Use normal activation” uses the criteria on the idle VE screen.
• TPS is below - Specifies the minimum throttle position to use this table.
• and RPM is below - Specifies the minimum RPM for using the idle VE table.
• and load is above - Specifies the maximum load for engaging the idle VE table.
• and CLT is above - Specifies the minimum coolant temperature for using the idle VE table.
• and VSS zero - Allows locking out the idle VE table unless the vehicle is stopped.
• and after delay - The minimum time for which these conditions must be met before switching
to the idle VE table.
These should usually be tuned in the same manner as the settings for engaging the idle advance
curve - see section 7.4.13.
The upper idle VE table is used for running off the main fuel table in place of VE table 1. The lower
idle VE table is normally inactive, and is only used when using dual fuel mode with an alternate AFR
table.
7.5 Accel Enrich
Section 6.3.5 covers basic acceleration enrichment tuning. Here, we’ll go over more advanced ways
to fine tune your transient fueling.
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7.5.1 TPS WOT curve
If you have enabled “TPSdot enables %WOT” under Accel Enrich Settings, this curve defines what
is considered wide open throttle for a given RPM. This curve should be set so that beyond this point,
additional throttle opening has no effect on the MAP sensor reading or air flow. The acceleration
enrichment will not add additional fueling once the throttle moves past the WOT level for your RPM,
as the additional throttle will not make the engine need more fuel.
7.5.2 Enhanced acceleration enrichment
Enhanced Acceleration Enrichment (EAE) is a model base acceleration enrichment setup that uses
a physics model to determine how much fuel the engine needs under changing load. This is more
complicated to tune than regular acceleration enrichment, but can produce superior drivability. EAE is
applied on top of regular acceleration enrichment, as the regular acceleration enrichment often reacts
faster, but you’ll want to reduce the amount of regular acceleration enrichment you use when you turn
EAE on.
The Enhanced Acceleration Enrichment feature is based on the concept that the fuel injected
does not all enter the engine on every injector squirt. Instead, a portion of the fuel collects on the port
and/or intake runner walls. The fuel collected there forms a puddle, from which some fuel enters the
engine on every intake event.
During steady-state conditions (such as cruise or idle), the amount of fuel entering the puddle,
the amount of fuel leaving the puddle, and the amount of each injector squirt going directly into the
engine reach a state of equilibrium. However, during throttle opening or throttle closing transient
conditions, the amounts of fuel entering the puddle, leaving the puddle, and going directly into the
engine change. Until equilibrium is reached again, the amount of injected fuel must change to ensure
that the intended amount of fuel (from the normal fuel equations and VE table lookup) still enters the
engine.
The EAE algorithm tracks the various quantities and adjusts the amount of fuel injected accordingly, but does so based on several adjustment curves and settings. The following curves are what
you’ll use to tune it.
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7.5.2.1 Adheres to Walls Coefficient
The X axis is the engine load. The number on the Y axis is what percent of the fuel sticks to
the walls at that load level, instead of going on into the cylinders. As a general rule, the number is
higher as the load goes up, and lower at low load since the vacuum helps vaporize the fuel. Engines
with injectors pointed sharply downstream or aimed precisely at the intake valve tend to have lower
coefficients, whereas engines with worse injector targeting can have higher numbers. An extreme
example would be a carbureted manifold converted to EFI where the only available injector location
has the injectors firing perpendicular to the intake runner - you’re going to get a lot of your fuel puddling
in the manifold.
7.5.2.2 EAE Sucked-from-walls coefficient
This curve determines how much fuel is being sucked from the walls on each intake (valve open)
event. It is a percentage (Y-axis) of the total amount of fuel that has adhered to the walls based on
load (X-axis), so therefore the percentages are much smaller (about 10x smaller) than the Adhere-towalls coefficients. It also typically increases with load - while the vacuum can help fuel vaporize, the
added mass flow can help pull the fuel off.
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7.5.2.3 EAE Adhere-to-walls RPM correction
This curve modifies the EAE Adhere-to-walls curve. It allows the amount of correction specified
by the EAE Adhere-to-walls curve to be increased or decreased based on RPM. As you may expect,
the higher flow rates at higher RPM tend to carry more of the fuel into the cylinders and result in less
on the walls.
7.5.2.4 EAE Sucked-from-walls RPM correction
This curve modifies the EAE Sucked-from-walls curve. It allows the amount of correction specified
by the EAE Sucked-from-walls curve to be increased or decreased based on RPM. The increased
flow rate at higher RPM tends to pull more fuel off the walls as well as preventing as much of it from
sticking in the first place.
7.5.2.5 EAE Adhere-to-walls CLT correction
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This curve modifies the EAE Adhere-to-walls curve. It allows the amount of correction specified
by the EAE Adhere-to-walls curve to be increased or decreased based on coolant temperature. The
default curve is flat.
7.5.2.6 EAE Sucked-from-walls CLT correction
This curve modifies the EAE Sucked-from-walls curve. It allows the amount of correction specified
by the EAE Sucked-from-walls curve to be increased or decreased based on coolant temperature.
Increased temperature will make the fuel evaporate faster.
7.5.2.7 Tuning EAE Since EAE’s main purpose is to ensure that the proper amount of fuel specified by the VE table (and other enrichments) actually gets into the engine, it is essential that the VE
table as close as possible to correct before tuning EAE. Since EAE must track the amount of fuel
collected on the port walls in order to function, it is also necessary for EAE to be enabled at all times
and the tables to be tuned everywhere, including cells you rarely hit. This includes the high RPM, low
load cells where you typically are running in an overrun fuel cut.
The following procedure should be followed to tune EAE:
1. Tune VE, Warmup enrichments, and all other fuel-related features.
2. Turn off normal Acceleration enrichment by setting the TPSdot and MAPdot thresholds to extremely high numbers.
3. Make sure that the VE table covers all the way down to Cranking RPM and to extremely low kPa
values.
4. Enable EAE in the Acceleration Enrichment dialog box.
5. With the engine at a steady RPM in a high gear, step on the throttle SLOWLY, and note the
response feel and the AFR.
6. At the same RPM, lift off the throttle, and note the response feel and the AFR.
7. Tune the EAE Adhere-to-walls curve and EAE Sucked-from-walls curve until AFR and response
are smooth and stable.
8. Make sure that the throttle movements used are small and slow, allowing the AFR to reach
steady-state before moving the throttle again. Make sure that the whole load range is covered,
and that every load seen during engine operation is covered by each of the curves.
9. Choose a few other RPM ranges, and slowly step on and release the throttle. Tune the EAE
Adhere-to-walls RPM correction and EAE Sucked-from-walls RPM correction curves until the
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response and AFR are correct at the RPMs chosen. Typically, you should start at the idle
and high cruise RPMs should be chosen. High cruise RPMs, for example are when speed is
maintained but the gear selection is reduced by one or two gears.
10. Shut off the engine, and allow it to cool completely.
11. Start the engine; as the coolant temperature increases, adjust the EAE Adhere-to-walls CLT
correction and EAE Sucked-from-walls CLT correction curves so that response and AFR are
stable.
12. Once small, slow throttle movements are tuned, larger ones can be verified, as well as normal
driving with gear shifts.
13. Finally, try to quickly blip the throttle while free-revving. If response is slower than desired, a
very small amount of TPSdot or MAPdot acceleration enrichment may be re-enabled. Take care
to only use it for high TPSdot values and use very little. Just enough to get EAE to respond is
all that is required.
The second set of EAE curves under the main ones are for use with dual fuel mode, as alternate fuels
often vaporize at different rates and need different tuning.
7.5.3 X-Tau acceleration enrichment
X-Tau is an alternate model based acceleration enrichment, with slightly different equations. This uses
a number called X to represent the percentage of fuel sticking to intake walls, and tau to represent
the amount of time it takes for the fuel that sticks to the walls to reach the cylinder. While EAE uses
a load scalar curve, X-Tau uses two separate, RPM based curves for acceleration and deceleration.
The X-Tau algorithm uses the rate of change of the MAP reading, not the absolute value of the MAP
reading, to determine which of these two curves to use. At steady MAP, it blends between the two.
7.5.3.1 Puddling Factors
This is the X term. There are two tables, one for acceleration and one for deceleration, which
represent what percent of the fuel puddles in the intake as a function of RPM. Note that in the way the
X-Tau numbering works, setting either curve to values above 48% can cause the fueling to oscillate,
particularly at low RPM, unless you use large tau values as well.
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7.5.3.2 Time factors
This is the tau term. This number represents the time, in milliseconds, for the fuel to travel from the
puddle to the cylinders. Valid numbers are from 10 msec to 2500 msec. The closer the fuel puddle is
to the intake port and the faster the air is moving, the lower the number. A port injected engine with
small intake runners and injectors targeted on the intake valves will be on the low side of the scale. A
throttle body injection intake will be on the high side.
7.5.3.3 X (Puddling) Temp Correction Factors
The temperature correction factors are enabled if you enable X-Tau with CLT correction. This is
a percent multiplier used to scale the accel and decel puddling factor curves as a function of coolant
temperature.
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7.5.3.4 Tau (Time) temp corrections
This is a percent multiplier used to scale the time factor accel and decel curves as a function of
temperature.
7.5.3.5 MAP
This determines whether to use the accel or decel tables. If MAPdot is above the start transition
threshold, the X-Tau accel tables are used. If MAPdot is less than (i.e., more negative than) the finish
transition threshold, the the X-Tau Decel tables are used. If MAPdot is in between, a blend of the 2
tables is used. Note that these are in negative kPa (i.e., put 40 if you want the threshold to be at -40
kPa/sec).
7.5.3.6 X-Tau tuning tips You should start with low X and low Tau, such as the default values. You
should then see if the X-Tau helps. Start by adjusting the X factor. If that doesn’t help, try increasing
the Tau time table entries in the areas where you are having troubles with lean spots (engine coughs
on accel).
The Tau time table is deliberately conservative, so in most cases it will require increasing, by
perhaps 50% to 100%.
You may need to try adjusting the lag filter values for the MAP sensor for less filtering. The X-Tau
mode needs to see the rapid rate-of-change of MAP and the lag filters can reduce this if set too low.
Generally you do not want to set it to less than 50%, and may need to set it to 70% to 80%.
As you dial-in the X-Tau parameters, the engine will likely become overly rich due to both normal
and X-Tau enrichments being applied. You can try reducing the existing TPSdot or MAPdot based
accel/decel enrichments, which do NOT go away when you specify the X-tau option and increasing
the X-tau variables. (Note that you may have to increase the cold accel multiplier as you do this.)
7.6 Boost / VVT
The MS3-Pro has multiple boost control strategies, and can control up to four channels of continuously
variable valve timing.
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7.6.1 Boost control settings
The MS3 Firmware has two algorithms for controlling boost:
• Open-Loop - Solenoid duty comes from an 8x8 duty table of TPS vs RPM.
• Closed-loop - A Proportional-Integral-Derivative (PID) loop controls solenoid duty to match the
actual boost to the boost target. An 8x8 target table of TPS vs RPM or a 6-point boost vs vehicle
speed curve is used to figure out the boost target.
In addition to the algorithm selection, there are several other settings that you will need to set up in
order to use the boost control feature.
7.6.1.1 Boost control common settings This section covers settings that are used by both the
open-loop and closed-loop control algorithms.
• Boost Control Enabled - This controls whether the boost control feature is enabled or disabled.
• Solenoid Frequency Range - This setting controls the frequency range of the valve. Mid range
allows 12 to 1021 Hz, while Slow allows 11.1 to 78 Hz but allows you to use a wider variety of
pins (such as more unused injector outputs) for boost control.
• Solenoid Frequency - Note that there are two drop down menus depending on whether you
are using Mid or Slow mode. This sets how many times to pulse the boost control solenoid off
or on. Many boost control solenoids work well from 19.5 to 78 Hz, depending on the valve - we
typically recommend 19.5 to 39 Hz for the boost control solenoid we sell.
• Boost Control Pin - This sets which output pin is used to control the boost control solenoid.
• Output Polarity - This is used to set the polarity of the output. Normal is used when you have a
conventionally set up boost control solenoid designed to go to minimum boost if it loses power
as a fail-safe; with this setting, higher duty cycle means higher levels of boost. Inverted means
that increasing the duty cycle decreases the boost.
• Control Interval - This setting is used to control how often the boost control algorithm runs.
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• Closed Duty - This setting controls the lowest allowed reported duty. Normally, this should be
0%.
• Open Duty - This setting controls the highest allowed reported duty. Normally, this should be
100%.
• Boost Control Lower CLT Threshold - To prevent running maximum boost before the engine
is warmed up, the MS3-Pro will run minimum boost until you reach this temperature, at which
point the boost control turns on.
• Algorithm - Specifies if you are using open loop or closed loop control.
7.6.1.2 Closed loop specific settings Enabling the closed-loop boost control algorithm enables
the following additional settings:
• Boost control use initial value table - If this is set to On, the boost control will start with an
initial duty cycle table whenever it moves into a new load cell as a feed-forward mechanism. If
it is set to off, the boost control will adjust from the previous duty cycle it was running at, and
operate purely from the feedback loop.
• Boost Control Lower Limit Delta - This regulates how close the boost must be to your target
to engage closed loop control. When the boost is more than this amount below your target, the
controller holds the valve wide open to maximize spool up speed.
• Tuning Mode - In Simple mode, the PID parameters are all set to 100% and you only tune with
the slider. In Advanced mode, you can adjust the PID parameters.
• Closed Loop Sensitivity - Use this setting to tune how agressively the boost controller tries
to reach the target boost. Adjust the slider up until the boost oscillates around the target, then
back down until it stops.
• Proportional Gain - Proportional gain affects the strength with which changes in input immediately affect changes in output.
• Integral Gain - The Integral Gain setting affects the response to continued difference between
the target boost and the actual boost.
• Derivative Gain - The Derivative Gain setting helps to slow down the response of the Proportional and Integral gain settings as the target is reached. This should be used sparingly as it
can also completely dampen the other two Gains.
The first step for tuning Closed-loop boost control is to set the desired targets in the Boost Control
Target table (section 7.6.3). Typically, lower throttle positions will have lower boost targets. This lets
you modulate the boost with the throttle.
Typically, the defaults for the following settings can be used:
• Control Interval - The default for this setting is 10 ms. This is typically a good place to start.
Lower settings can be used if overshoot cannot be tuned out when tuning the PID parameters.
• Closed Duty - A closed duty of 0% is the default. This should be tuned to the value that starts
to open the wastegate, but typically 0% works well.
• Open Duty - An open duty value of 100% is the default. This should be tuned to the value that
fully opens the wastegate, but typically 100% works well.
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• Boost Control Lower Limit - This setting is used to set the pressure at which PID boost control is
engaged. The default for this setting is 100. If a faster rise to target is desired, this setting can
be set to a higher number, but the safest number is 100 since it gives the PID code the most
time to react to climbing boost.
The next step after setting up the target table and supporting settings is to adjust the slider for best
performance. If the slider on its own does not give the results you hope for, you can go to advanced
mode and tune the PID gains:
1. Set Integral and Differential Gains to 0% - This will let you focus on tuning the proportional gain.
2. Set Proportional gain to 100% and slowly lower - While tuning Proportional gain, higher numbers
mean slower boost climb and lower final boost. For safety, start with a very high gain (100%
should be sufficient). Find the RPM that typically spools quickly, and fully and quickly depress
the accelerator. Note how much boost is reached. If boost overshoots the target dramatically,
increase the Proportional gain. Otherwise, reduce the Proportional gain and try again. Do this
until boost reaches the target with a small amount of overshoot.
3. Tune the Integral Gain - The next step after the target is reached consistently is to tune the
Integral gain. Starting from the RPM used to tune the Proportional gain, fully depress the
accelerator and watch the boost as the engine climbs through the RPM range. As the engine
accelerates through the rev range, the boost will probably creep away from the target. Keep
increasing the Integral gain until the controller adequately maintains the target with minimal
oscillation. It may be necessary to increase the Proportional gain a bit after tuning the Integral
gain since the two gains tend to counteract each other.
4. Tune the Derivative Gain - Increase the Derivative gain until the overshoot is minimized. Care
must be taken when increasing the Derivative gain as too much Derivative gain can overdampen the effects of the Proportional and Integral gains.
7.6.1.3 Overboost Protection Overboost protection works similarly to a rev limiter, except that it
can stop engine operation when boost exceeds a user-set limit. In addition, use of the overboost protection feature is required when using the closed-loop boost control algorithm. The following settings
affect the operation of overboost protection:
• Overboost Protection - Activates overboost protection and lets you specify what action to take
when boost exceeds the maximum boost number.
– None - Disables overboost protection.
– Fuel Cut - Stops the engine by cutting fuel.
– Spark Cut - Stops the engine by cutting spark.
– Both - Stops the engine using both fuel and spark cut.
• Maximum Boost - The maximum boost (in kPa) at which the engine should be operated.
• Hysteresis - The amount boost must drop by (in kPa) after hitting the maximum boost before
fuel or spark are restored.
• Overboost switching - Allows you to use an input to raise or lower the point at which overboost
protection engages. For example, you might want one setting for pump gas and another for race
gas, and can use a switch to let the MS3-Pro know which you are running.
• Alt Maximum Boost - The boost level to allow when the overboost switch is active.
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Setting this ups very similar to setting up a rev-limiter. Choose from Fuel Cut or Spark cut or Both.
Do not use spark cut mode if the engine still has a catalytic converter. Spark cut can cause backfires
that melt or break the catalyst.
The maximum boost should be set up higher than the maximum target boost will be in the closedloop boost target table. Hysteresis should be set so that MAP jitter does not cause it to alternate
rapidly between on and off. Remember, overboost protection is not telling the MS3-Pro “I would
prefer my boost level stays below this setting;” it is more like, “Shut down my engine at once if the
boost gets this high!” And the MS3-Pro will react with that same level of urgency.
7.6.1.4 Other Boost Control Settings The following settings remain:
• Boost Table Switching - This option when enabled allows a switch input to be configured which
switches between two different boost duty or target tables. You can also allow it to switch tables
based on gear by selecting “Gear-based”.
• Boost Table Switching Gear - If boost table swithcing is set to gear based, the MS3-Pro will
switch to the second boost table when you shift into this gear and above.
• Boost Timed From Launch - If launch control is enabled, this setting allows a specific boost
duty or target to be used for a set amount of time after launch.
• Specific Launch Duty/Target - If launch control is enabled, this setting controls what target
(closed-loop) or duty (open-loop) is used for boost control.
• Launch Boost Duty - This is the duty used by Specific Launch Duty/Target, if using open loop
boost control.
• Launch boost target - This is the boost target used by Specific Launch Duty/Target, if using
closed loop boost control.
• Boost by speed / gear - this item enables the use of the boost vs speed curve. You may set it
to use one of two speed sensors if enabled.
• Above TPS % - This setting is used in conjunction with the Boost vs Speed function. Below
this TPS setting, the normal boost tables are used. Above this TPS setting, the boost vs speed
curve is used.
• Per Gear Targets - Specifies the boost target in each gear if boost by gear is active.
7.6.2 Boost control duty table
This is the table you use to tune open loop boost control.
To tune this table, start with small values (the default table is all zeroes) and increase the numbers
until you reach the desired amount of boost. Use open-loop boost control to try out different frequency
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settings and find the settings that work the best for the particular solenoid being used. We recommend
using open loop boost control to establish that the boost control setup is working before you use closed
loop control.
The second duty cycle table (Boost control duty table 2) can either be used for switched boost or
a second wastegate.
7.6.3 Boost control target table
When using closed loop control, this table specifies what boost level to target in kPa as a function of
throttle position and RPM.
The second table (boost control target table 2) can either be used for a second wastegate or for
switched boost.
7.6.4 Boost control initial duty table
This is a feed-forward table. If the initial value table is enabled, whenever the target boost level or
RPM changes, the MS3-Pro will look up what duty cycle to start with. The X axis is the engine RPM,
while the Y axis is the target boost level. As with the other tables, the second table (boost control
initial duty table 2) can either be used for a second wastegate or for switched boost.
7.6.5 Boost delay
This screen is active if you enable “Boost timed from launch” and launch control.
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This specifies how long to go from no boost (if the initial value is not used) or the specified initial
value (if used) to full boost after you release the launch control switch. This is a percentage of the
regular boost, so it should end at 100% boost.
7.6.6 Boost control vs speed
This allows you to specify the amount of boost allowed (closed loop) or solenoid duty cycle (open
loop) as a function of ground speed.
7.6.7 Boost 2 control settings
The boost control 2 menu is for twin turbo setups, either sequential or compound. Use these settings
if you have a second solenoid valve controlling a second wastegate independently of the primary
wastegate. Setups that use a single solenoid to control two wastegates do not need these settings.
As the screen notes, you cannot use this with timed, speed, or switched boost control.
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• Boost control enabled - allows a second solenoid output using the second set of boost tables.
• Boost control pin - specifies which output to use for the second solenoid.
The closed duty, open duty, lower limit, algorithm, and PID settings work in the same way as the
primary boost control settings.
• MAP sensor to target - When running in closed loop, the second boost control solenoid will
not target the main MAP sensor, as most setups that require different wastegate pressure from
side to side also require different compressor outlet pressures. You will need to define what the
second MAP sensor is on the Generic Sensor Inputs screen in the Advanced Engine menu.
7.6.8 Turbo anti-lag (ALS)
Anti-lag is a combination of features you can use to keep the turbo spooled while shifting, beyond
the basic flat shift rev limiter. The MS3-Pro has several strategies it can use to dump extra fuel into
the exhaust and increase exhaust gas temperatures under these conditions. This increase in exhaust
temperature will shorten turbo life and possibly result in increased wear and tear on other parts of the
exhaust system as well.
All anti-lag variations require an input switch to arm the system. When active, the anti-lag system
will add fuel and retard timing to a number specified by the ALS tables. You can also allow the
MS3-Pro to use the following additional strategies when the anti-lag is active:
• Use a cyclic fuel cut
• Use a cyclic spark cut to dump unburned fuel into the exhaust
• Activate a solenoid or additional injector output to send fuel or air into the exhaust manifold
directly
• Open the idle valve a set amount
• Open a solenoid to let additional air into the intake manifold
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Note - use extreme caution if using any system that dumps fuel directly into the exhaust! This
type of anti-lag can turn “danger to manifold” from an ironic “The Fast and the Furious” reference into
a very real hazard.
As many anti-lag systems also have the throttle or idle control valve open by a large amount, the
MS3-Pro can also use a rotational idle fuel cut to reduce idle speed on engines using anti-lag. The
rotational idle engages when anti-lag is off.
Anti-lag is only used when you release the throttle to shift; see the Launch Control section for how
to set up the MS3-Pro for no lift shifting.
Since anti-lag creates so much heat, the MS3-Pro has several settings to limit the anti-lag system’s
use to limit heat buildup.
• Anti-lag enable input - Select what input pin is used to arm the anti-lag system.
• Maximum TPS - Specify the maximum throttle position for anti-lag to be active.
• Minimum RPM - Anti-lag is shut down if the RPM drops below this point.
• Maximum RPM - Anti-lag is disabled above this RPM.
• Maximum MAT - Anti-lag shuts down if the air temperature goes over this point.
• Maximum ALS time - The longest allowable time, in seconds, for the anti-lag system to operate.
• Time between activations - This is used to prevent a brief sensor reading out of the anti-lag
range from resetting the anti-lag timer. The MS3-Pro treats any set of activation conditions in
this time block as a single activation, even if it briefly comes out of the TPS or other conditions
that would activate anti-lag.
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• Minimum CLT - The lowest coolant temperature at which anti-lag can be used.
• Maximum CLT - Anti-lag is disabled above this temperature.
• Enable cyclic fuel cut - If this is turned on, the anti-lag system will use a rotating fuel cut when
active.
• Enable cyclic spark cut - Cuts spark when the anti-lag system is active.
• Enable roving idle fuel cut - This uses a secondary fuel cut to reduce idle speed. Roving idle
fuel cut is active when anti-lag is off.
Note that cyclic fuel cut and roving idle fuel cut only work with full sequential fueling. They do not
work in semi-sequential or batch fire fuel modes.
• Use idle valve - If set to on, the idle valve will open an additional amount when anti-lag is active.
• Idle valve duty - The amount of extra duty cycle to apply to a PWM valve if the idle valve is
active.
• Idle valve duty steps - Like the above setting, but for a stepper IAC valve.
• On/off output - Allows you to activate an on/off output when anti-lag is active. Use this setting
to specify which pin.
• PWM output (generic PWM F) - Allows you to turn on a PWM output when anti-lag is active.
• Output port / pin - Specifies the output pin for the PWM output.
• Output duty - The PWM output is driven at a fixed duty when anti-lag is active. Use this setting
to specify what duty cycle.
• Frequency - Specifies the frequency to use with the PWM output.
7.6.9 Turbo anti-lag tables
Anti-lag functions operate on a TPS vs RPM basis. The TPS range is fairly low as anti-lag is only
active at part throttle. The tables available will depend on what anti-lag options have been enabled,
although the Added Fuel %age and ALS Timing will always be available if anti-lag is on.
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• Added fuel %age - The amount of extra fuel to add when anti-lag is active.
• ALS timing - This is a timing table in absolute numbers which the MS3-Pro will use when anti-lag
is active. As the MS3-Pro specifies timing with BTDC numbers being positive, negative numbers
indicate to retard the timing to after top dead center.
• Spark cut % - The percentage of spark events to cut if cyclic spark cut is enabled.
• Fuel cut % - The percentage of injection events to cut if cyclic fuel cut is enabled.
7.6.10 ALS roving idle fuel cut %
This screen is enabled when the roving (rotational) idle is enabled. It allows you to set the percent
of fuel injection events to cut to limit idle speed on cars that do not allow added air bypass items
and therefore have the throttle adjusted open to allow more air to flow into the turbo with the throttle
“closed”. Note that the right hand column needs to be set to all zeroes.
7.6.11 VVT settings
Many engines now feature variable valve timing. This allows a balance between engine performance
and economy, with the ECU automatically adjusting the valve timing to suit operating conditions. The
particular implementation varies with engine and manufacturer. The first systems available are of the
"on/off" variety where the cam is moved by a fixed angle only, and there is no feedback systems.
Examples of this include:
• Honda first generation VTEC
• Toyota first generation VVT
• BMW single VANOS
More advanced systems use continuously variable cam controls - typically an oil solenoid valve controlled by a PWM signal from the ECU. The ECU uses one camshaft position sensor per cam to
compare the cam advance to a crankshaft position sensor reading. Examples of continuously variable systems include:
• Toyota VVTi
• BMW double VANOS
• Ford Zetec and Ti-VCT
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Most continuously variable VVT systems use a single solenoid where a duty near 50% holds the cam
in position. More than 50% causes it to advance or retard. Less than 50% moves it in the opposite
direction. Since the duty cycle controls the direction the cam moves and not the absolute position,
continuously variable valve timing requires closed loop control. The MS3-Pro uses a missing tooth
wheel (or otherwise irregular pattern) on the crankshaft compared to a sensor on the moving cam to
determine camshaft position, and uses this to adjust the solenoid duty cycle.
Note that outside of the V10 applications, BMW’s Double VANOS is a bit of an oddity - it uses
separate solenoids to advance and retard the cam, much like a 3 wire PWM idle control valve.
If you are controlling more than one cam, you will need to use the digital frequency input circuits
for cam input. These can read most Hall effect sensors with no modification. If your engine uses VR
type camshaft position sensors, you will need external VR conditioner circuits to read the additional
sensors.
• No. VVTs - the number of VVT actuators to be controlled
• Cam Decoder - Standard mode works with either cam teeth that are all equally spaced, or a
hard coded spark mode. Nonstandard cam decoders work with engines that use Toothed Wheel
mode with an unusual cam wheel. Currently supported modes include BMW V10s, the BMW
S54’s double VANOS setup, and Chrysler VVT Hemi engines. All of these use a 60-2 crank
trigger.
• Frequency - the PWM output frequency. Adjust to suit your solenoids.
• On/Off or PID - the mode of operation. Full variable systems should use PID.
• Adjust inj. timing based on - whether the Injector Timing for sequential injection should be
adjusted as the cams are moved.
• Commanded vs Actual - If the injection timing adjustment is on, this specifies whether the
commanded or actual timing is used to make the adjustment.
• Inj. Timing Adjustment - for on/off mode, this specifies the Injector Timing adjustment when
VVT is on.
• Test output - during initial setup the test mode is used to confirm solenoid operation and learn
the cam range of movement. The output specifies which cam should be altered.
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• Test duty - the PWM duty cycle to be applied to the chosen VVT output under test.
• Control Interval - Synced to Cam adjusts the duty cycle each time the MS3-Pro updates its
data on the cam position, which usually gives the best response. Timed mode adjusts the duty
cycle once per specified timed interval.
• Control Interval Time - the time interval in milliseconds for adjustments in timed mode.
• Range Check Measured Angles - Checks to see if the measured range is within the minimum
to maximum settings. If the cam moves out of range, this triggers a cam fault.
• Minimum VVT Duty - The lowest duty cycle to use for the solenoid.
• Maximum VVT Duty - The highest duty cycle to use for the solenoid.
PID Parameters - these are used to adjust the closed loop feedback. There are separate settings for
intake and exhaust.
• Use hold duty - Specifies whether to default to a set value when no cam change is commanded.
• Hold/neutral duty - the duty at which the cam stays still.
• Proportional gain - Proportional gain affects the strength with which changes in input immediately affect changes in output.
• Integral gain - The Integral Gain setting affects the response to continued difference between
the target cam angle and the actual angle.
• Difference gain - The Derivative Gain setting helps to slow down the response of the Proportional and Integral gain settings as the target is reached. Usually smaller than the other two
numbers.
• Table is Advance / Retard - Controls whether the table reads the degrees advanced from the
minimum advance, or degrees retarded from minimum retard. Intake cams always use advance,
while exhaust cam tables may use a retard table instead.
Cam Settings - allow you to specify each cam’s output, function, and range of movement.
• Input - the position sensor input for this cam. (Cam 1 always uses the main cam sensor input
set in Ignition Settings.)
• Polarity - The capture polarity of the cam input. (Cam 1 typically follows the main settings.)
• No. teeth - How many capture teeth on the cam wheel.
• Output - where the PWM solenoid valve is connected.
• Minimum - the minimum absolute angle from the cam sensor. See setting up. This is the angle
of the signal from the sensor - not necessarily the actual cam center angle.
• Maximum - the maximum absolute angle from the cam sensor.
• Int./Exh. - specifies if the cam is an intake or exhaust cam. This determines the PID parameters,
direction and target table to be used.
• Tooth 1 - only used by BMW V10 at present. Look for the cam tooth edge after this crank tooth
no.
• Tooth 2 - same again, but for second crank revolution.
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• More duty means - whether more PWM duty on the solenoid causes the cam to advance or
retard.
Note that on dual solenoid applications, such as the BMW S54 mode, the Cam 1 solenoid is used to
advance the main cam and the Cam 3 solenoid is used to retard the same cam. Cam 2 advances the
secondary (usually exhaust) cam, while Cam 4 retards this cam.
The most basic setup is to make the wiring connections for inputs and outputs. Most engines will
run safely with VVT inactive; ensure this is the case on your engine. Having completed the wiring,
set the basic configuration reflecting the wiring choices you made, the control type and the number of
teeth on the cam wheels. Leave the min/max cam angles as zero for now.
On your TunerStudio dashboard, enable the gauges VVT_angle (1,2,3,4 as required). Start the
engine and observe the VVT angle gauges. Use the test mode for each VVT with 0 and 100% duty and
observe the swing of the cam angles. You will hear the engine tone change as the cam angle changes.
It is important that the VVT angles you observe are stable and vary evenly. With continuously variable
cam timing, the VVT angle will normally swing from fully retarded to fully advanced (and vice versa)
quite quickly with any duty beyond the hold/neutral duty, so it will be unlikely that you will be able
to catch the cam at anything other than the limits of its travel. Double check that the cam min/max
angles are presently set to zero.
For each cam, record the minimum and maximum angles you observe while varying the test duty.
Enter these into the min/max fields. Note that the maximum MUST be larger than the minimum. (In
the instance where the angles cross 720 degrees, add 720 to the maximum angle. e.g. if minimum
was 700 and maximum was 40 degrees, enter 700 and 760.) At this stage you should also be able to
determine if more duty is retarding or advancing each cam.
Having configured the inputs and outputs, proceed with PID tuning. Take datalogs and observe
the VVT actual angle compared to the target angle. We recommend tuning in much the same way as
boost control. Start with the I and D terms zeroed out, dial in the P term first, followed by the I. If you
have problems with the cam overshooting its targets, gradually increase the D term until it damps out
the overshoots.
Once the cam control is working, you may dial in the VVT activation tables. These are usually best
to dial in on a dyno.
7.6.12 VVT intake and exhaust tables
The intake and exhaust VVT tables show the cam position as determined by the angle of the cam
sensor signal relative to the crankshaft position sensor. Usually, this one requires dyno tuning to
determine what settings perform best.
7.6.13 VVT on/off table
For on/off mode, no feedback of cam position is used and most settings on the VVT settings screen
are unused and grayed out. The output value, frequency and injector timing adjustment are set
through the main settings screen. In place of the angle target table, an on/off table is used. In this
table, set 100 for cells where VVT should be active and 0 for cell where it should be inactive. Do not
use other values.
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7.7 Table Choices
For many installs a single fuel table is all that is required! New users are strongly advised to
start with a single table!
MS3-Pro offers a number of methods of switching and blending between tables. These methods
can be used to effectively extend the basic table size, for better tunability with different fuel algorithms
(e.g. low vs high rpms), for dual fuels, or for different fuel mixes. Presently, fuel, ignition, boost
and AFR targets may be blended or switched. Due to the complexity introduced with multiple tables,
only experienced users should consider enabling these features. Additionally, the algorithm blending
should only be enabled once each table is well tuned. Autotuning (VE Analyze Live) will not function
on some combinations of blended tables.
Terms used:
• Table switching - the ability to swap from one table to another, based on RPM, TPS, MAP or a
physical switch input
• Combined tables - two tables are combined to give a single VE (or spark) result
• Algorithm blending - two tables with different calculation algorithms are used to calculate fuel
(or spark) and then the result is blended together
• Dual table - two tables operate independently to control injectors or injector banks
• Staged injection - one fuel calculation control two banks of injectors. e.g. small injectors for
idling and larger injector for full power. (See Staged Injection page.)
Algorithms are different strategies for determining the "load" on an engine and then calculating fuel
and spark etc. As a brief recap:
• Speed-Density - Uses MAP as load.
• Alpha-N - Uses TPS as load.
• MAF - Measures actual airflow. Spark load uses a calculated percentage of cylinder filling.
• %baro - Uses MAP divided by barometric pressure as load.
• ITB - Uses a mix of MAP and TPS as load.
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7.7.0.1 Example scenarios Why use table switching or blending at all? Actually, most users won’t
need to, and can get by just fine with a single table. Here are some examples of engines that could
genuinely need table switching or blending.
• A big block Chevy has two different types of port designs, one half of which flow considerably
better than the other half. Such an engine may need true dual table mode (although you can
also use the individual cylinder trim to achieve the same effect.)
• A large cammed motor with a poor MAP signal below 2,000 RPM that stabilizes at higher RPM
could use blended alpha N and SD, with the motor running on alpha-N at low RPM and speed
density at high RPM.
• A turbo motor with a very large MAF for good fuel metering that runs out of MAF resolution at
low flow could use blended speed density and MAF fueling, with speed density at low RPM and
the MAF at high RPM.
• A motor with a very wide powerband could use two separate speed density tables, switching
them based on RPM. This can effectively be used to create a 30 x 16 fuel table.
• A motor with switchable intake runners could use separate tables for when the long runners are
open vs when the short runners are open.
• A race car that runs in classes with different fuel requirements could have separate maps for
pump gas and race gas.
• A vehicle with a flex fuel sensor can blend in between separate gasoline and ethanol maps,
interpolating between the two for the percent of fuel in the tank.
7.7.0.2 Fuel blending and switching types
There are four VE tables, numbered 1 through 4.
Here are some of the possible combinations of fuel table blending and switching. Electrical symbols for switches and variable resistors illustrate the switch or blend functions.
Method
Diagram
Single table. One fuel algorithm uses VE1.
This is the most common setup.
Single algorithm, with table-switching.
One fuel algorithm uses VE1 or VE3
depending on table switch setting/input.
Could be used with dual-fuel or also as a
method to extend effective table size.
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Single algorithm with table-blending. One
fuel algorithm uses a proportion of VE1 or
VE3 depending on the blend input and curve
(3).
The tables could be blended based on
ethanol percentage in the fuel from a flex-fuel
sensor.
Combined tables - secondary additive
table. Fuel is calculated by adding the
lookup from VE1 and VE2.
VE2 can be used a tweak to VE1 to add a
4th dimension to the fuel table e.g. including
a throttle component in a speed-density tune.
0% in the secondary table means no change,
2% means add 2%
Combined tables - secondary
multiplicitive table. Fuel is calculated by
multiplying the lookup from VE1 and VE2.
VE2 can be used a tweak to VE1 to add a
4th dimension to the fuel table e.g. including
a throttle component in a speed-density tune.
100% in the secondary table means no
change, 102% means add 2% etc.
Secondary algorithm blended table. Fuel
is calculated from VE1 using the primary fuel
algorithm and also from VE2 using the
secondary fuel algorithm and then the result
is blended.
This could be used to have a blend between
a Speed-Density in VE1 and MAF tune in
VE2. The blend curve (1) allows you to alter
where each algorithm is in use. Each table
should be tuned individually i.e. set the curve
to 0% and tune VE1, then set to 100% and
tune VE2, afterwards enable blending.
Two way blend.Fuel is calculated from VE1
and VE3 using the primary fuel algorithm.
These are blended. Then VE2 and VE4 are
calculated using the secondary fuel
algorithm and blended. The VE1/3 result is
then blended with the VE2/4 result.
This could be considered for E85 (VE3/4) vs
regular gasoline (VE1/2) where algorithm
blending is also used between left and right,
such as a blend of Speed Density and MAF.
This is incompatible with ’Dual Table’ as that
uses VE3/4 for the second bank.
Two way blending is complex ! Do not enable
it without fully tuning each individual table.
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Dual table. Fuel for injector bank 1 is
calculated from VE1 and fuel for injector
bank 2 is calculated from VE3.
This could be used where an engine has
radically different fuel requirements between
banks (or cylinders in a V twin.) or as part of
a dual-fuel install where the second bank is
used for LPG or methanol etc.
Injector staging. Fuel is calculated from
VE1 and the staging parameters determine
the split between primary and secondary
injectors.
This is typically used on engines with a large
dynamic range so that small injectors may be
used at low loads for good tunability with
additional (staged) large injectors coming
online at full power. This concept is used
from the factory on Mazda rotary engines.
More variations. There are many more
combinations possible to include double
blending, switching between blended tables
etc.
These are partially set in the Basic / Load Settings and partially set in the Table Choices menu.
7.7.0.3 Fuel settings
Single algorithm, single table
By far the most common install is to use a single Speed-Density fuel table. This really
should be your starting point before considering other load methods and certainly before multipletable configurations are enabled.
Multiply MAP controls whether MAP is included in the calculation for VE1 (and VE3). For regular
Speed-Density this should almost always be enabled. For "Pure" Alpha-N, leave it disabled. For
"Hybrid" Alpha-N, enable it. For MAF, it is ignored.
Single algorithm with table switching
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Here we have table switching enabled in the upper left hand corner of the Table Switch / Dual
Fuel menu. A physical switch input (shown here connected to “Digital Frequency In 1”) is used to
swap between VE1 and VE3 for fueling. The same algorithm is used for both tables. The RPM, TPS,
kPa switch points can be used as a form of table extension where say VE1 is 0-3500rpm and VE3 is
3500-7000rpm.
Single algorithm with table blending
Blend curve (3) is used to define the blend between VE1 and VE3 which use the same algorithm.
At 0% of ’sensor9’ (could be a trim pot) the fuel is calculated from VE1. At 100% of ’sensor9’ the fuel
is calculated from VE3. In-between, proportions of table will be used. It is very important to tune each
table individually - trying to retune with a partial blend is likely to result in confusion or failure.
Dual table
Fuel for injector bank 1 is calculated from VE1 and fuel for injector bank 2 is calculated from VE3.
This can also be used in conjunction with VE1/2 (and VE3/4) combined tables and algorithm blending.
It is not compatible with table switching or blending from VE1 to VE3.
7.7.0.4 Spark / ignition blending and switching types There are also four spark tables, with
switching and blending options similar to fuel.
Some options are not present as they do not apply to ignition; you cannot multiply spark tables,
for instance, or stage two sets of spark plugs (although the rotary split tables are a similar idea).
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Method
Diagram
Single table. One ignition algorithm uses
Spk1.
This is the most common setup.
Single algorithm with table-switching.
One ignition algorithm uses Spk1 or Spk3
depending on table switch setting/input.
Could be used with dual-fuel or also as a
method to extend effective table size.
Single algorithm with table-blending. One
ignition algorithm uses a proportion of Spk1
or Spk3 depending on the blend input and
curve (2).
The tables could be blended based on
ethanol percentage in the fuel from a flex-fuel
sensor.
Combined tables - secondary additive
table. Ignition is calculated by adding the
lookup from Spk1 and Spk2.
Spk2 can be used a tweak to Spk1 to add a
4th dimension to the fuel table e.g. including
a throttle component in a speed-density tune.
Secondary algorithm blended table.
Ignition is calculated from Spk1 using the
primary ignition algorithm and also from
Spk2 using the secondary ignition algorithm
and then the result is blended.
This could be used to have a blend between
a Speed-Density in Spk1 and MAF tune in
Spk3. The blend curve (2) allows you to alter
where each algorithm is in use. Each table
should be tuned individually i.e. set the curve
to 0% and tune Spk1, then set to 100% and
tune Spk2, afterwards enable blending.
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Two way blend.Ignition is calculated from
Spk1 and Spk3 using the primary ignition
algorithm. These are blended. Then Spk2
and Spk4 are calculated using the secondary
ignition algorithm and blended. The Spk1/3
result is then blended with the Spk2/4 result.
This could be considered for high-octane
(Spk3/4) vs low octane (Spk1/2) where
algorithm blending is also used between left
and right.
Single table
By far the most common install is to use a single Speed-Density ignition table. This really
should be your starting point before considering other load methods and certainly before multipletable configurations are enabled.
Single algorithm with table switching
In the above screen shot, the MS3-Pro is set to switch the spark tables at 5000 RPM. You can also
set the switching to kPa or throttle position, or use a physical switch.
Single algorithm with table blending
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Blend curve (4) is used to define the blend between Spk1 and Spk3 which use the same algorithm.
Here it is used for gear based spark table switching. Spk1 is used for gears 1,2,3. Spk3 is used for
gears 4,5. It is very important to tune each table individually - trying to retune with a partial blend is
likely to result in confusion or failure.
Combined tables - secondary additive table
Spk1 is combined with Spk2 using addition (the advance numbers are added together.) This can
allow a secondary algorithm to act as a modifier or as a means to extend table size e.g. Spk1 =
0-100kPa and Spk2 = 100-400kPa with the same primary and secondary algorithm selected. In the
above screen shot, it’s being used to extend tables.
Secondary algorithm blended table
Blend curve (2) is used to define the blend between Spk1 and Spk2 which may use different
algorithms. Here it is used to blend between the spark tables based on flex fuel percentage. It is
very important to tune each table individually - trying to retune with a partial blend is likely to result in
confusion or failure.
7.7.0.5 AFR blending and switching types
There are two AFR tables, AFR1 and AFR2.
The MS3-Pro has three options for choosing these.
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Method
Single table.Target AFR is determined from
AFR1.
This is the most common setup.
Switched tables.Target AFR is determined
from AFR1 or AFR2.
A physical switch input determines which
table is used.
Diagram
Blended tables.Target AFR is determined
as a blend between AFR1 and AFR2 using
Blend Curve (5) .
The target AFR is then be used for closed loop EGO or for Incorporate AFR. Note that even in
"Dual Table" mode, only a single AFR target number is in use at one time. Both channels will target
the same number if closed loop is enabled.
7.7.0.6 Boost table switching Like with the AFR tables, there are two boost tables, and you can
either use one table, switch tables, or blend them. These work the same way as AFR table switching,
except that you have the option of setting the boost table switching to use a gear input instead of a
hardware switch, so you can use a different boost map in lower gears if you are traction limited. The
boost table blending uses blend curve 6.
Note that you could effectively create a third boost setting by using a switch to shut off power to a
boost control solenoid. The result would give you the lowest boost level permitted by the wastegate
spring.
In Closed Loop mode these two tables are target boost. In Open Loop they are raw boost solenoid
duty cycle.
Method
Diagram
Single table. Boost is determined from
boost table 1.
This is the most common setup.
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Switched tables. Boost is determined from
boost table 1 or boost table 2.
Either a physical switch or a gear option
determines which table is used.
Blended tables. Boost is determined as a
blend between boost table 1 and boost table
2 using Blend Curve (6).
7.7.1 Table Switch / Dual Fuel
This screen sets up many of the table switching options, as well as settings for running an engine on
multiple fuel types.
Several of the settings have been covered in the previous section; here, we’ll explain the settings
we have not yet covered.
• Req Fuel Switching - Allows you to use a hardware input to change the base pulse width
number. The MS3-Pro will use the lower number when the switch is active and the higher
number when the switch is off.
• Alternate ReqFuel - The number to be entered when the switch is active.
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• Stoich Switching - Switch to the alternate stoichiometric ratio number (for purposes of using
the “incorporate AFR” into the fuel calculations) when the switch is active.
• Alternate Stoich - The air/fuel ratio used when the switch is active.
• Dual fuel enable - Enables dual fuel or dual table mode.
• Mode - Allows either dual table mode or switching between two sets of injectors.
• Outputs mode - You can either use two sets of injectors wired to the same outputs and a relay
to switch between them, or a second set of outputs for the secondary fuel injectors. Note that
the code assumes that the same switch triggers the relay and the input pin - the MS3-Pro does
not trigger the relay.
• Secondary outputs - You can either use the injector I and J in batch fire, or use the remaining
outputs in the injector A through H series.
• Secondary v3 alternate - If using injectors I and J in batch fire, this determines if they fire at
the same time or alternate.
• Input pin - Specifies what input is used to signal to switch to the secondary fuel.
• Alt parameters - allows switching the specified numbers when the dual fuel input pin is active.
• Enable temperature adjustment - Allows you to turn on a curve to compensate for fuel temperature for secondary fuel.
• Temperature on - Allows you to select the fuel temperature sensor. This must be defined in
Generic Sensor Inputs.
• Enable pressure adjustment - Allows you to use a curve to compensate for fuel pressure on
the secondary fuel.
• Gauge pressure in kPa on - Allows you to specify a pressure sensor for the secondary fuel.
This also must be defined in Generic Sensor Inputs.
7.7.2 Temperature Adjustment
This screen is enabled for the secondary fuel in the dual fuel menu. This curve gives a percentage
multiplier that is applied to the fueling as a function of temperature.
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7.7.3 Pressure Adjustment
This screen is enabled for the secondary fuel in the dual fuel menu, and is intended for gaseous
fuels, which often can have the tank pressure drop below regulator set pressure. It allows adjusting
the fuel amount in percent as a function of fuel pressure.
7.7.4 Alt Injector Dead-time 2
If you are using a second set of injectors for dual fuel mode, this screen allows you to specify separate
dead time values for these. It works just like the primary dead time screen.
7.7.5 Alt Injector small pulsewidths 2
This works like the primary injector small pulse widths, but applies to a second set of injectors when
dual fuel mode is enabled.
7.7.6 Blend curve menus
The MS3-Pro has six blend curves for blending multiple tables. Each curve has a specific function.
1. Blend curve 1 blends between a primary and secondary fuel algorithm (VE1 and VE2).
2. Blend curve 2 blends between a primary and secondary spark algorithm (Ignition 1 and Ignition
2).
3. Blend curve 3 blends between two fuel tables on the same algorithm (VE1 and VE3). If using a
two way blend, blends between VE2 and VE4 as well.
4. Blend curve 4 blends between two ignition tables on the same algorithm (Ignition 1 and Ignition
3). If using a two way blend, blends between Ignition 2 and Ignition 4 as well.
5. Blend curve 5 blends between AFR tables 1 and 2.
6. Blend curve 6 blends between boost tables 1 and 2.
7. Blend curve 7 blends cranking pulse widths. Typically used for E85 flex fel applications.
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The curves all work in the same manner.
The % is the amount of the second (higher numbered) table to use, with the remaining percent
being on the lower numbered table. The X axis can be set to several different types of inputs:
• TPS - Throttle position
• MAP - MAP sensor reading
• RPM
• MAF load
• Flex% (percent ethanol in fuel, as measured by a flex fuel sensor)
• VSS1 - driven wheel speed
• Gear - transmission gear position
• RPM * Load / 100
• Generic sensor inputs
7.8 Advanced Engine
7.8.1 Speed and gear sensors
The vehicle speed sensors (VSS) allow one or two wheel speeds to be monitored. The MS3-Pro
allows one or two speed sensors, with the second one being used to measure wheel slip for traction
control. The inputs read from either a wheel/axle mounted pickup or a perhaps pickup that is part of
the transmission. The input can be magnetic (with suitable interface) or more directly a hall type input.
This input is converted to a linear speed (mph or kph). The shaft speed inputs work in a similar way
to the vehicle speed but calculates to rpms. It could be used as gearbox input shaft speed to monitor
convertor or clutch slip. The VSS output feature provides a pulsed output in proportion to the VSS for
driving a digital speedometer. The gear detection calculates the current gear selected in the gearbox
by a number of methods.
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You can use the Project Properties screen to set the units, both mph vs kph and meters vs inches,
in the Settings tab under Project Properties, or you cna change them with the settings in the lower
corner of this table.
There are four options for speed input.
1. Analogue linear input where 0V = zero speed and 5V = max speed.
2. Digital pulse input to MS3-Pro
3. MS3-Pro collects speed value from remote CAN device
4. MS3-Pro collects pulse data from remote CAN device
7.8.1.1 Analogue linear input A 0-5V signal is applied to one of the analogue inputs. Set the
analogue sensor input channel, the full scale speed, and the smoothing lag factor.
7.8.1.2 Digital pulse input to MS3-Pro This is most easily achieved with a hall-type sensor applied to one of the frequency or switched digital inputs. Analogue sensor should be set to Off and the
0-5V input pin specified as the Input. Set wheel diameter, VSS position, number of teeth and lag factor. There are many options for mounting a reluctor and sensor on the vehicle; two basic categories
exist - wheel mounted and driveline mounted.
Wheel mounted Select this when your sensor is picking up on a shaft spinning at the same
speed as the wheels. Possibly the simplest option here is a gear tooth sensor (such as the Honeywell
1GT101DC) in close proximity to the back of the wheel studs, or a pre-existing ABS reluctor.
Driveline mounted Select this when your sensor is picking up on a shaft before the final drive
gear. e.g. gearbox output shaft, driveshaft. (This is most likely the setting to use for RWD transmission
mounted sensors.) Many transmissions already offer a VSS output. If this is suitable, you may be
able to just tap into this. Alternatively, you could add a magnet on the output flange and a hall sensor.
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7.8.1.3 Speed value from a remote CAN device In the case where you have, say, a CANconnected transmission controller that is already calculating vehicle speed, you can simply configure
MS3-Pro to collect this number. Analogue sensor should be set to Off and CANVSS specified as the
Input. Set scaler% and lag factor. Internally, MS3-Pro stores speed in units of 0.1 ms-1 (metres per
second). To convert from a remote device using mph, a scaler of 46% would apply. Configure the
CANVSS offset/table/id through the CAN menus.
7.8.1.4 Pulse data from a remote CAN device This is similar to option 2, but the VSS connects to
a remote CAN device, the time between pulses is collected and MS3 calculates the speed. Analogue
sensor should be set to Off and CANPWMin specified as the Input. Set wheel diameter, VSS position,
number of teeth, PWM port and lag factor. Configure the CANPWM offset/table/id through the CAN
menus.
7.8.1.5 Menu settings
• Analogue sensor - If using an analogue sensor (method 1) this is set to the analogue input.
Otherwise, set it to Off
• Full scale speed - only used with an analogue sensor. Sets the speed reported on a 5V input.
Assumes 0V = 0 speed.
• Input - specifies either the digital pulse input or CAN input. Not used with analog sensors.
• Wheel diameter - only applies to methods pulsed input modes.
• VSS position - either wheel or driveline - applies to methods pulsed input. If using driveline, be
sure to set your final drive ratio.
• Speed sensor #teeth - how many teeth the reluctor has - used with pulsed input
• PWM port - the CAN PWM "port" being used - only used with pulsed input over CAN.
• Scaler - applies a scaling to the CAN collected speed value, for units conversion. Applies if
using CAN.
• Smoothing lag factor - Smoothing on the speed value. Lower numbers mean more delay and
smoothing. Sensible range is 15-100.
7.8.1.6 VSS dot smoothing These settings control how the VSSdot (acceleration) calculation is
performed. The lower the sample interval, the more responsive the calculation but the noisier it will
be. Experimentation will be required to get the best settings for your application. Calculating launch
acceleration is particularly difficult to get right. Very low tooth counts and wheel speed collected via
CAN will be the most difficult due to the low data rate and the communication delays.
7.8.1.7 VSS output This allows the MS3-Pro to provide a scaled output based on speed sensor
#1 to control a speedometer.
• VSS output - specifies which output channel to use.
• VSSout units - valid units are as follows:
– Time
– Pulses per mile
– Pulses per kilometer
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• Scale - If “pulses per mile” or “pulses per kilometer” is selected, this is how many pulses to put
out per unit of distance. If “time” is selected, the time between output pulses is calculated as
time factor / speed in meters per second.
7.8.2 Shaft Speed Sensors
These use digital pulsed inputs to determine speed of other components in the car for data logging.
For example, you can log the converter output shaft speed in an automatic transmission. Currently,
shaft speeds are just recorded and displayed, but not used for any other calculations.
High speed input mode allows more precision, but is not available on all inputs. If it is available on
your input, it is best to turn this on.
This mode allows fractional teeth in case the sensor is driven by a gear or other mechanism that
results in a non-integer number of outputs per shaft revolution.
7.8.3 EGT / Thermocouple settings
The EGT system in MS3-Pro allows inputs from EGT sensors to be datalogged by serial or SDcard.
It optionally allows the engine to be shut down if EGT exceeds a set temperature. If an EGT probe is
fitted to each exhaust port, it can be used in conjunction with per-cylinder fuel trim to balance cylinders
to account for air flow and injector flow differences. EGT is used extensively in piston driven aircraft
and much useful information can be found from aircraft literature and then applied to your non-aero
engine. (EGT differences between cylinders can be significant at idle. Evidence shows that V8s often
run cold on the four corner cylinders and hot on the inner four. One engine required over 10% fuel
trim to balance these air-flow differences.)
To use the EGT system an EGT probe (usually a K-type thermocouple) is installed in the exhaust
manifold. When installing an EGT per cylinder, it is typical to install ~50mm from the head.
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The thermocouple output is a small voltage that the MS3-Pro will not read directly. There are two
ways you can connect a thermocouple to the MS3-Pro:
• An amplified that converts the signal to a 0-5 volt reading which you can connect to an MS3-Pro
analog input
• A CAN enabled thermocouple interface like the CAN-EGT input module that transmits the data
over the CAN bus
• No. EGT inputs - specify the number of channels you have connected
• Calibration - the calibration depends on the thermocouple amplifier in use. Consult the documentation that came with it.
• Data Capture - here you specify the local or remote analogue channels that the EGT inputs are
connected to. For remote CAN inputs, see the CAN section for configuration.
The Actions section allows you to specify action if EGT gets too high.
• Warn temperature - above this temperature the code will take action. The warning output
selected on the AFR Safety system is turned on.
• Add fuel - specifies a raw pulsewidth in milliseconds of additional fuel. This could be used to
help protect the engine if EGT is too high.
• Add to - Normally this is set to "Both". When using staged fuel outputs or dual table, you may
want to specify a particular channel.
• Shutdown engine - if you want, the engine to be shutdown if EGT is too high.
• Time > warn temp - if any of the EGT stays above the warn temperature for more that this time,
the engine is shutdown.
• Max temperature - if any of the EGTs exceeds this temperature, then the engine is shutdown
immediately.
See the AFR Safety system for shutdown and resume settings.
The temperatures, pulsewidth and time presented are purely examples. It is very important that
you review your datalogs and think carefully before specifying these settings. With correct settings,
EGT overtemp is likely to detect a failing injector causing a lean mixture on one cylinder or an overall
problem such as a faulty pump or regulator causing everything to run lean.
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7.8.4 Generic sensor inputs
The Generic Sensors allows optional analogue inputs to be connected and easily recorded in datalogs
or used as parameters in the Output Ports. The analogue inputs are in the 0-5V range and are
internally converted with a 10bit ADC (Analogue to Digital Convertor), giving 1024 steps. Typical
uses include:
• Pre- and post- intercooler pressure and temperature
• Fuel pressure
• Nitrous pressure
• Exhaust backpressure
• Pedal position
• Suspension travel
The MS3-Pro has three built in 0-5 volt inputs. You can also bring analog sensors in over the CAN
bus.
Each sensor channel is turned on individually. Once it is enabled it will appear in datalogs. The
channels are named sensor01, sensor02....up to sensor16.
7.8.4.1 Source To enable a channel, change the source from "off" to a specific input. The Analog
In 1 through Analog In 3 are built into the MS3-Pro. CAN ADC01-24 are analogue inputs collected
from a remote CAN connected board(s) and must be configured in the CAN section before use.
7.8.4.2 Field Name
You can set a description of the field, to improve readability.
7.8.4.3 Transformation This specifies how the raw 0-1023 number the MS3-Pro sees internally
should be turned into something meaningful to you. These are your options.
• Raw - just the raw 0-1023 number. This is mostly of use for troubleshooting.
• Linear - apply a linear conversion from 0V to 5V values. This is appropriate for many sensors
• Same as MAP - if you have an identical pressure sensor as the main MAP sensor
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• Same as CLT - if you have an identical temperature sensor and bias resistor as the main CLT
sensor
• Same as MAT - if you have an identical temperature sensor and bias resistor as the main MAT
sensor
• Same as EGO - if you have an identical EGO calibration as the main EGO sensor
• Same as MAF - if you have an identical Mass Air Flow sensor as the main MAF sensor calibration
• GM calibration - if you have a GM temperature sensor and standard (2490 ohm) bias resistor
7.8.4.4 0V, 5V value
These are only used with the Linear transformation.
• 0V value - specifies the number you want to see when 0V is applied
• 5V value - specifies the number you want to see when 5V is applied
Many sensors specify output at other voltages, e.g. some data sheets advise pressure at 0.5V and
4.5V. This needs to be converted to the 0V and 5V values using a calculator.
Take the following numbers:
“A” = low voltage
“B” = high voltage
“C” = low pressure
“D” = high pressure
Calculate E = (D - C) / (B - A)
0V value = C - (E * A)
5V value = (E * 5) + 0V value
Let’s work these out with an example sensor: Honeywell’s 2000 psi sensor, part number MLH02KPSB06A.
This sensor has a linear (ratiometric) output voltage range of 0.5V to 4.5V from zero to full pressure. It is a 2000psi gauge sensor that would be suitable for measuring nitrous line pressure 0.5V is
0psi 4.5V is 2000psi
Calculate the 0V and 5V values as above. Take A = 0.5V, B = 4.5V, C = 0psi, D = 2000psi
E = (D - C) / (B - A) = (2000 - 0) / (4.5 - 0.5) = 2000 / 4 = 500
0V value = C - (E * A) = 0 - (500 * 0.5) = 0 - 250 = -250 (yes, this is negative) 5V value = (E * 5) +
0V value = (500 * 5) - 250 = 2500 - 250 = 2250
For this particular sensor, you would enter -250 in the 0V box and 2250 in the 5V box. Those
values are never actually reached, but this gives the correct calibration.
7.8.4.5 Lag The smoothing factor to apply. This uses the same number system as lags elsewhere.
100% means no smoothing and lower numbers give increased smoothing and lag to the input. 15%
is a sensible lower limit.
7.8.4.6 CLT/MAT temp units
Specify the temperature unit system you want.
7.8.4.7 Allow Input Sharing Normally each input can only be used by one feature. This setting
allows inputs to be shared between generic sensors and other features. (Obviously you can still only
connect one sensor to each input!) For example, you may want to enable a sensor as an EGT input,
but also have TunerStudio display the raw voltage from the sensor.
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7.8.5 Accelerometer parameters
The accelerometer input allows for a user-supplied one, two or three axis accelerometer to be connected to the MS3-Pro and datalogged. It may be connected to any of the spare analogue inputs or
remotely via a CAN.
The accelerometer is calibration to +/-1g for convenience, but internally the code uses SI measurement units (m per second squared) so accelerometer acceleration can be compared to vss measured
acceleration.
However, BEFORE enabling the accelerometer, your need to collect the calibration data.
7.8.5.1 Collecting calibration data
nected to Analog In 1 through 3.
In this example we will assume that the three axes are con-
• Ensure that the accelerometer is wired in and powered on.
• Open up Generic Sensors and define three spare "sensors" with the three accelerometer inputs.
Set the transformation to “Raw”.
• Next, define a gauge on your TunerStudio dash to match one of these inputs. Right click on a
gauge and then re-define it to match one of the sensor inputs you just defined.
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• Physically move and rotate the accelerometer until it gives the minimum reading on that gauge.
Write it down.
• Repeat for the maximum reading on that gauge. Write it down. The minimum value will be for
-9.81ms-2 (-1g) and the maximum will be for +9.81ms-2 (+1g).
• Repeat for all three axes.
• Return to the Generic Sensors screen and turn off the three inputs you defined.
• Go to the Accelerometer dialogue and enable the three inputs and enter the pairs of calibration
data you captured.
• The process is now complete, and in future the acceleration will be recorded in datalogs as
accelX, accelY, accelZ.
7.8.6 Traction control settings
The MS3-Pro offers several strategies for traction control:
• VSS Slip %: The MS3-Pro compares a speed sensor on the driving wheels to one on the
non-driven wheels, and reduces power if the driving wheel speed exceeds the non-driven wheel
speed by a specified amount.
• Perfect Run: The MS3-Pro monitors a single speed sensor. You specify the maximum speed
the vehicle can reach in a given amount of time, and the MS3-Pro considers any acceleration
faster than this to be wheel spin and engages traction control. As this strategy is intended for
drag racing, Perfect Run traction control requires starting with launch control active to engage.
• Perfect Run RPM: A variant of traction control for racing events which do not allow the ECU
to monitor vehicle speed. In this mode, you specify the engine RPM as a function of time.
The MS3-Pro will engage the traction control if the RPM increases faster than the specified
curve. Like regular Perfect Run, this mode requires starting with launch control active before it
engages.
• Switch Input: The MS3-Pro engages traction control in response to a signal from an external
traction control module. Used on cars with OEM traction control modules which send an on/off
signal, such as some Corvettes.
Traction control allows several different responses to reduce power, depending on what features you
are using.
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• Retarding the spark timing.
• Using a rolling spark cut.
• Adding fuel.
• Reducing or shutting off a nitrous oxide injection system.
• Reducing boost on a turbocharged motor.
7.8.6.1 Traction control settings
• Traction control - Allows turning traction control off or on.
• Method - Specifies what method is used to determine when to apply traction control.
• Enable input - If set to “off,” traction control is active full time (for switched input or VSS %slip)
or active any time the launch control system is used (for Perfect Run). This can specify an input
pin used to arm traction control.
• Minimum TPS - Specifies the minimum throttle position below which traction control is not
applied.
• Minimum MAP - Specifies the minimum MAP reading below which traction control is not applied. (Not used for Perfect Run)
• Minimum VSS - Traction control is not used below this speed. (Not used for Perfect Run)
• Slip % setting - If set to “Fixed value,” you specify the maximum percent the drive wheel speed
can exceed the non driven wheel speed with the Slip Threshold % setting. “Adjustable” allows
you to use an external dial to change the slip threshold.
• Slip threshold - The maximum amount of wheel slip permitted in VSS % slip mode.
• Nitrous control - Current firmware only supports on/off. In on/off mode, nitrous is left on if the
Nitrous Cut curve is less than 40%, and cut if nitrous cut % is over 60%.
• Add fuel to - If using added fuel, specifies if this is applied to the first stage (Bank 1), secondary
injectors if used (Bank 2), or both.
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7.8.7 Traction control - perfect run VSS
This screen lets you specify the maximum speed for the traction control to allow as a function of
the time after launch control deactivates. After passing the top time point, the traction control turns
off.
7.8.8 Traction control - perfect run RPM
This works in the same manner as the perfect run VSS screen, except you specify the maximum
engine RPM to allow as a function of time. This provides a slew control function instead of true traction
control, to meet various sanctioning body rules.
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7.8.9 Traction control - External % slip input
Allows you to specify the maximum slip percent to allow as function of the amount of input from
an external adjustment knob.
7.8.10 Traction control reactions
This screen lets you specify what actions to take if traction control is active. The MS3-Pro can be
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set to take more action the longer the traction control is active. The slip number is different based on
the method used.
• For VSS% slip, it is the percent by which the driving wheel speed exceeds the non-driven wheel
speed.
• For perfect run, it is the percentage difference in acceleration or time vs the target.
• For switched mode, off is 0% slip and on is 100% slip.
With on/off nitrous cut, we recommend setting the nitrous cut at 0 for leaving the nitrous off, and 100%
to cut off the nitrous.
7.8.11 Launch / 2 step / 3 step / T-Brake
The MS3-Pro launch control system is a 2-step limiter, typically used in drag racing applications for
consistent hard launches and/or to build boost with a turbocharged engine. The flat shift settings
allow full throttle shifts on a clutched vehicle. A switch on the clutch triggers the flat-shift rev limiting
(for bikes, see also the sequential shift cut, which may be more suitable.) It is important to install the
clutch switch with adjustability, as the exact height has an effect on how well flat-shifting works. Flat
shift is unlikely to be useful when running an automatic transmission. The 3-step is typically used as
a burnout limiter and will often be linked to a line-lock.
A typical drag racing scenario would go like this: You pull forward into the burnout box, stand on
the brakes and flick on the line-lock. This also enables the 3-step. You now do your burnout and the
3-step limits are applied. After your burnout, you pull into stage, depress the clutch (activating the
launch switch) and then push the throttle to the floor. The launch settings will hold the engine close to
your chosen rpm. When you change gear, keep the throttle planted, and only use the clutch. Now the
flat shift settings come into play, and the revs will be limited to those settings. After changing gear and
lifting your foot off the clutch, the limiter is disabled. Be sure to also set the normal rev limiter should
you miss shift.
7.8.11.1 Basic launch control / flat shift settings
• Launch control option
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– Off - all of launch if turned off
– Launch - launch only, no flat shift
– Launch/flatshift - launch and flat shift
• Input on - where the launch input switch is connected
• Launch hard limit - when the launch conditions are met, above this rpm the hard limiter methods are used
• Soft Limit Zone - When the RPM is this far below the launch hard limit, the MS3-Pro will apply
spark retard, and if spark cut is used, it will begin to phase in a partial spark cut.
• Soft Limit Retard To - This is the timing (in absolute degrees BTDC) that the MS3-Pro will
command while in the soft limit zone.
• Launch retard above - when the launch conditions are met, the timing is retarded above this
rpm
• Retard to - the absolute timing to retard to. For example, if you enter 5 in here, the timing will
be 5 BTDC, -3 means 3 ATDC. Using ATDC timing can be useful for building boost, but beware
of the potentially harmful heat it generates in the turbo too.
• Launch fuel add/remove - Allows fueling to be changed while the launch limiter is on.
• Fuel addition - the raw millisecond pulsewidth change to make (+/-)
• Enable launch when TPS above - launch is only active when the throttle is open a certain
percentage. Most users can safely set this to a very low number. Setting it too high can cause
launch not to activate as expected.
• Limiter method
– None - Launch control itself is not activated. However, this will allow you to use timed
features that activate after a launch, such as timed boost control or perfect run traction
control.
– Spark cut - drop sparks; this is the most common limiter used. (Will not work with EDIS
ignition or some other semi-autonomous ignition controls.)
– Fuel cut - cuts fuel. Seen by many as risky due to the possibility of partly fueling, but if your
ignition goes into a limp home mode if you try to cut it off, this may be your only option.
– Spark and fuel - both
• Disable launch when VSS above - If you have set up a speed input, this allows you to lock out
the launch control when the vehicle is in motion.
Flat shift settings:
• Disable Flat-Shift when VSS Below - Prevents flat-shift from activating at low speeds, such as
just after launch.
• Flat shift arming rpm - this rpm set point is used to differentiate between a flat shift and launch
condition. Typically as you are preparing to start a launch you will be at lower rpms, while for
flat shift you operate the clutch near your rev limit. So set the flat shift arming rpm to say 3/4
or your max rpms. i.e. consider what rpms are you doing when you press the clutch and make
sure the code will always know if you want the launch limits or flat shift limits.
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• Flat shift hard limit - The maximum RPM to use when flat shift is active. Uses the same soft
limit zone as launch control.
• Soft Limit Retard To - This is the timing (in absolute degrees BTDC) that the MS3-Pro will
command while in the soft limit zone during a flat shift.
• Cut fuel above - this is intended to be used during flat shifting. During the up-shift as the revs
are falling, the fuel is cut off until the revs have fallen below this set point. This reduces the raw
fuel in the exhaust system that can otherwise produce a loud backfire.
• Timed retard after launch - Allows you to set a spark retard that is active immediately after
launch. The MS3-Pro will then use a time based curve to put the timing back in. Use this to
reduce power if you have wheelspin, but are running in a racing series that doesn’t allow traction
control.
7.8.11.2 Variable launch settings The variable launch mode allows you to adjust your launch
control RPM limit with a 0-5 volt input, allowing you to adjust your launch control for changing track
conditions.
• Variable launch input
– Off - disables the feature and uses the single limits
– One of the analogue inputs - indicates what input pin is being used for the variable launch
• minimum setting - With a 0V input, the launch hard limit is set to this rpm.
• maximum setting - With a 5V input, the launch hard limit is set to this rpm
• soft limit lower by - The soft launch limit is this many rpm below the variable hard limit.
1000rpm is typical.
7.8.11.3 Transbrake and throttle stop The MS3-Pro can control many timed delay functions for
bracket or drag racing. The trans brake control applies the trans brake when you press the trans
brake input button. When you release the button, the trans brake will remain on for the delay time,
then release. Launch control is enabled while the trans brake is on, and releases at the same time
as the transbrake. The throttle stop output switches on after launch, stays on for a set time, then
releases.
• Transbrake button input - Specify what input pin is used for the transbrake switch
• Transbrake output - Specify what output pin is used for the transbrake control.
• Delay - The time, in seconds, between releasing the transbrake input and releasing the transbrake.
• Turbo Staging Button - Press this button, and the MS3-Pro will pulse the trans brake off and
on, allowing the car to creep forward while building boost.
• Release Time - How long to release trans-brake for on each move step. This should be set long
enough to move the car a little without gaining any speed.
• On Time - How long the trans-brake should be re-activated for between each step. This should
be set long enough to fully grab again.
• Main # Moves - How many moves (trans-brake release steps) on the first press of the button.
Each subsequent press of the button gives a single move.
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• Throttle stop output - Specify what output pin is used for a throttle stop.
• On delay after launch - The time, in seconds, between releasing launch control and the throttle
stop turning on.
• Keep on for - The time, in seconds, to keep the throttle stop active.
7.8.11.4 3 step / burnout limiter This is another switch operated limiter that works similarly to
launch. It could be used as a burnout limiter and the input switched along with your line-lock.
• 3 step input - Allows you to turn this feature off or specify an input pin to activate the 3 step.
• Soft Limit Retard To - the absolute timing to retard to.
• Hard limit - when the 3-step is on, above this rpm the hard limiter methods are used
7.8.12 Timed retard after launch
If you have enabled “Timed retard after launch” in the Launch Control screen, this screen allows
you to adjust the timing immediately after launch. This curve specifies how much timing to subtract
from the regular timing curve, in degrees, as a function of the seconds after the launch control has
been released.
7.8.13 Sequential shift cut
Another drag racing feature, this one is intended for use with air shifters and sequentially shifted
transmissions. The MS3-Pro can cut the ignition during shifting and also control the air shifter solenoid
valve. Note that automatic shift control and gear based delays require setting up the gear input under
Speed and Gear Sensors. The shifting will happen in this sequence:
1. As soon as the button is pressed or automatic shift is required, the air shifter solenoid is turned
on.
2. The MS3-Pro pauses for a time defined by the shift cut delay before cutting spark.
3. The MS3-Pro waits for the specified spark cut time plus any gear based delay, if applied. During
this point, the solenoid turns off before the ignition resumes.
4. The ignition resumes firing.
5. The MS3-Pro starts the re-shift hold off timer. The MS3-Pro will not shift again until this timer
runs out.
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• Shifter Spark cut system - Toggles this feature off or on.
• Mode
– Button - The shift cut is activated by an external button.
– Auto - The MS3-Pro controls the shifting using preset RPM points. Pressing the button will
force an upshift.
• Button input - Select the channel for the switch to activate the shift cut. Usually, this button is
in the shifter mechanism itself.
• Solenoid output - Select the output pin for an air shift solenoid.
• RPM > (RPM) - The shift cut will only operate above this RPM.
• And TPS > (%) - The minimum TPS reading to activate the shift cut.
• Delay before spark cut - The time, in seconds, between the input shift and cutting the spark.
This is to allow the solenoid to start moving.
• Spark cut time (base) - The amount of time, in seconds, for the spark cut to be applied.
• Gear based delay - Turning this on allows you to add an extra amount of spark cut time in one
or more gears.
• Additional delay settings - These add a small number of extra spark cut for the specified shift
• Solenoid delay - the time to allow the solenoid to deactivate before re-applying spark
• Re-shift hold off time - Disables the shift cut for the specified time after shifting, to avoid
accidentally triggering.
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• Shift RPM - These five points let you specify the RPM for each shift if running in automatic
mode.
7.8.14 Nitrous system
Nitrous oxide injection is primarily used in racing applications where nitrous oxide and additional fuel
are injected into the intake to give a horsepower boost. This is particularly popular in drag racing.
Used correctly, nitrous can give perhaps 100% additional power. Used incorrectly, it can melt pistons
and destroy engines in seconds. The nitrous system within MegaSquirt allows control over the nitrous
and optional fuel solenoid to enable the nitrous injection when desired and also retard the ignition
timing. The system supports two stages of control with on/off or progressive.
There are two main categories of nitrous systems - wet and dry. You can further subdivide this
into on/off, progressive, and multistage nitrous systems.
7.8.14.1 Wet flow nitrous A wet system injects fuel into the manifold ahead of the injectors. This
can result in fuel distribution problems and mixture varying between cylinders. The simplest example
of a wet system is a "plate" system that installs under the throttle body (or carb) above the intake
manifold and delivers nitrous and fuel through spray bars. Other variations exist which use single
or multiple nozzles. A standalone wet nitrous system has the advantage that when used with the
suppliers suggested jetting it will typically install and work. More hardware, less tuning.
7.8.14.2 Dry nitrous With a dry system, the fuel injectors supply additional fuel when the nitrous
is active. Systems designed to work with OEM engine management sometimes do this by increasing
fuel pressure, which does not give accurate fuel increase across the rev range, but with MS3-Pro, we
can directly increase the injector pulse width instead. The nitrous enters through a nozzle typically
located upstream of the throttle body.
In a port-injection system, a dry nitrous system minimizes the fuel distribution problems. A dry
system can also have fewer system components, as it uses the existing fuel system components.
However, because the fuel and nitrous can be controlled independently, the software settings are
critical to getting the mixture correct. Less hardware, more tuning.
7.8.14.3 On/Off With On/Off control, the nitrous/fuel solenoids are either on or off. This is the
standard operating mode.
7.8.14.4 Progressive control The Progressive system allows you to pulse you solenoids with
output duty varying with rpm or time during drag pass. It is more complicated to setup than the On/Off
system.
7.8.14.5 Multistage and progressive nitrous Note! - you are advised to always start with a
simple system using small jets. Big hits with multiple stages or progressive are significantly more
difficult to install and tune correctly.
With a single on/off stage using fixed jetting, the flow of nitrous (and fuel) is approximately constant
under all conditions. This means that if you are getting a claimed 100hp at 3000rpm when you activate
the system, by 6000rpm the engine is turning twice as fast and each intake event will only receive
half the nitrous/fuel, so you will get half the torque benefit. One answer might be to use two stages
based on rpm. The first stage is still jetted at 100hp, but at 4500rpm you bring in a second stage
of say 25hp. This will make up for some of the "lost" torque. Another approach would be a single
stage progressive system using "200hp" jets. You could start at ~50% duty at 3000rpm and ramp up
to 100% duty at 6000rpm. This could keep a similar torque gain across the rev range.
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7.8.14.6 Tuning considerations In general, applying up to 50% extra hp to your engine with a kit
manufacturer’s jetting and suggested retard works well and will not cause problems to your engine.
However, it is very important to take plug readings and check for any signs of leanness or detonation.
As mentioned already, it is quite easy to destroy your engine with nitrous given the wrong combination.
Easy mistakes to make with bad consequences:
• Mixed up fuel/nitrous jets.
• Fuel pressure too low (mismatched to fuel jet size)
• Incorrect dry fuel pulsewidth
• Insufficient timing retard
• Too hot a spark plug
• Faulty fuel solenoid or wiring
• Blocked fuel lines or jets
• System activated at too low an rpm
7.8.14.7 Nitrous settings
• Nitrous Control - Turns the system on or off
• Enable N2O when above - sets the minimum RPM to enable nitrous.
• And Coolant Temp above - sets the minimum coolant temperature to enable nitrous.
• And TPS > - sets the minimum throttle position to enable nitrous (Typically, nitrous should only
be enabled on a warmed up engine at wide open throttle at an RPM point where the engine is
making at least as much horsepower as the nitrous shot provides.)
• Max RPM - sets the maximum RPM to enable nitrous. You will want this off before the rev limiter
engages.
• Enrich which bank - Set to "Both" for most installs. If "dual table" or Staging are in use it selects
which injector bank receives any additional fuel pulsewidth.
• On/Off vs Progressive mode - Selects between On/Off or Progressive control mode.
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• Time-based or RPM-based - For progressive, chooses between time or RPM as control factor.
• Solenoid frequency - For progressive, selects solenoid frequency.
• AFR safety uses AFR2 targets - Allows optional AFR safety system to use alternate AFR
targets when nitrous is active.
Stage 1 settings:
• Stage 1 output - nitrous - Selects output pin to use for stage 1 nitrous solenoid
• Stage 1 output - fuel - Selects output pin to use for stage 1 fuel solenoid (These will normally
be the same for an on/off system, but may be different for progressive.)
• Enable input on: - Selects the input pin to use to enable the nitrous system. We recommend
using the digital 12 volt input pin for nitrous. If you’re using a conventional arming switch, this
allows you to wire the input to the nitrous solenoid power source.
• Additional Fuel PW @ N2O min rpm - In on/off mode with a dry system the fuel PW to add at
the min rpm.
• Additional Fuel PW @ N2O max rpm - In on/off mode with a dry system the fuel PW to add
at the max rpm. (In between these two rpm points, the MegaSquirt calculates the required
pulsewidth using linear interpolation.)
• Retard Ignition by - In on/off mode sets a fixed ignition retard.
• Nitrous delay after launch - Sets a minimum time after launch control before nitrous can activate.
• Nitrous delay after flat shift - Likewise for flat shift.
Stage 2 settings:
• Stage 2 output - nitrous - Selects output pin to use for stage 2 nitrous solenoid
• Stage 2 output - fuel - Selects output pin to use for stage 2 fuel solenoid
• Enable stage 2 above - In on/off mode, sets the activation rpm for stage 2.
• Max rpm - In on/off mode, sets the maximum rpm for stage 2.
• Delay after stage 1 - Sets a minimum time delay after stage 1 activates before stage 2 can
activate. (To prevent a massive hit.)
• Retard Ignition by - In on/off mode sets a fixed ignition retard for stage 2.
• Additional Fuel PW @ N2O min rpm - In on/off mode with a dry system the fuel PW to add at
the min rpm.
• Additional Fuel PW @ N2O max rpm - In on/off mode with a dry system the fuel PW to add at
the max rpm.
The progressive feature adds another level of control and complexity. The solenoid duty, added fuel
and timing retard for one or two stages can be plotted out against rpm or time giving you fine control
over nitrous operation. You’ll need to experiment to determine the best duty cycles. The way most
solenoids work, 50% duty is rarely equal to 50% flow. You will likely find that fuel and nitrous solenoids
vary in behavior too (due to different coils and liquid pressures, among other factors.)
As always, experimentation and careful testing, datalogging and refinement will be required to
make the most of this feature.
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7.8.15 Nitrous - time based progressive
This requires the use of the MegaSquirt launch control system and the time is measured from the
release of launch. This is only really of use in drag racing. This allows you to specify the amount of
nitrous duty cycle, fuel (in raw pulse width numbers), and timing retard (in degrees) for both stages of
a progressive nitrous system.
7.8.16 Nitrous - time based progressive
These curves work in the same manner as the time based progressive curves, but use RPM for
the X axis instead of time.
7.8.17 Water injection
Water/meth injection is primarily used in boosted applications for charge cooling to reduce the tendency to knock, often allowing boost to be increased. Due to limited capacity of water/meth reservoirs
this will mainly be of use for short duration sprints and less of use for endurance racing. (Make sure
the reservoir does not run empty! The MS3-Pro can use a level switch to check this.)
The MS3-Pro system can control a pump via a relay when conditions are met and map the duty
cycle of a water valve on a 3D map of duty vs MAP vs RPM. The valve may either be fast acting (runs
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at injector speed) or a slow speed similar to a boost solenoid.
• Enable water/meth injection - enables or disables the feature.
• Pump Output - output pin to control pump relay.
• Valve style - select
– "Off" - no valve output (used fixed nozzle)
– "Slow" - slow speed valve output with chosen PWM duty cycle
– "Fast" - valve switches at injector speed with chosen PWM duty cycle
• Valve Output - output pin to control water valve.
• Frequency - selects the output frequency to the valve. (Slow mode only.)
Enable when...
• TPS > - enable when TPS is above this %age
• RPM > - enable when RPM is above this value
• MAP > - enable when MAP is above this value
• MAT > - enable when MAT is above this value
• Use maxAFR shutdown - This allows using a level switch on an input pin connected to the
MS3-Pro. When the level switch activates, the MS3-Pro will behave as if it has been shut down
from the AFR Safety feature.
The 3D table controls the valve duty cycle as a function of RPM and MAP sensor readings.
Water injection will almost certainly alter your reported AFRs, and you should therefore ensure
that closed-loop EGO control is not operating when water injection is active. Set the EGO control so
that open-loop mode is used at the boost levels where you plan to enable water injection.
7.8.18 High Power Time Enrichment
Engines that run flat out for long periods of time often require a richer air/fuel ratio than what would
make best power. This is needed to cool down the combustion chambers and reduce the vulnerability
to detonation. MS3-Pro allows ramping up the air/fuel ratio during sustained full throttle operation so
that you can tune for a maximum power air/fuel ratio, then add fueling if the engine stays under power.
Applications that can benefit from this include:
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• Road race vehicles
• Boats
• Air cooled engines
To use this feature, you will need to turn on Incorporate AFR Target under Basic / Load Settings ->
General Settings.
You can specify the minimum load and RPM to apply this feature. Once the engine is running in
this range and this feature is active, it will adjust the air/fuel ratio as a function of time until the engine
drops below the active load or RPM range. The curve specifies AFR decrease (richer) vs. time. It
is normal for the first row to be 0, 0. The second row typically specifies when the enrichment should
begin. e.g. 7, 0. This means that there is no change from 0-7 seconds as both are set to a 0 decrease
in AFR. The third row onwards specify the richening.
7.8.19 Oil Pressure
The MS3-Pro can monitor oil pressure and trigger a smart warning light. This feature can also be
used to trigger the check engine light. Setting the minimum pressure to more than zero on startup will
ensure that the oil pressure warning light turns on when you turn the key on, so you can make sure
it is working. The light will come on if the oil pressure goes above the maximum pressure vs RPM
curve or below the minimum pressure curve. You will need to define the input sensor under Generic
Sensors.
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7.8.20 Programmable on/off outputs
This screen is for setting up generic on/off outputs for features like shift lights, variable intake control
solenoids, and other items that don’t need complicated control settings.
Note that if you’re using one of these outputs for another function, you don’t want to enable it here.
For example, if you’re using PWM / Idle Out 1 for idle control, don’t enable it here. Enabling it here will
tell the MS3-Pro that you’re trying to use PWM / Idle Out 1 as some sort of on/off output at the same
time, and the MS3-Pro will report a configuration error.
7.8.20.1 Output port pane In the left hand pane, ports currently configured through this system
are shown with a green bulb. To configure a port, click on the name to highlight it and then view or
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alter the settings in the right hand pane.
7.8.20.2 Port settings pane
• Enabled This enables or disables the selected port. (Toggles green bulb on/off) Do not try to
configure a port already used for another feature.
• Power On Value Whether the output should be on or off when MS3-Pro first starts. Ensure that
this matches up with the conditions the MS3-Pro is likely to see on startup.
• Trigger Value The output state when your conditions are met. Typical settings would have the
power on value as Off and the trigger value as On.
7.8.20.3 Conditions
This pane is where you specify the logic that activates the output.
Output channel This is a list of MegaSquirt variables - much the same as the various gauges
you can select in TunerStudio.
>=<
This “logical operator” forms part of the equation.
• > is greater than
• = is equals
• < is less than
Usually, you don’t want to use the = sign here. This will turn on the output only when the variable is
exactly equal to the threshold number, with zero difference. There are a few variables, such as SD
card error conditions, where this can be useful. Most of the time, a variable won’t hit your threshold
right on the nose, and the output will stay unactivated.
Threshold
The value compared against.
Hysteresis It is very common for a value to hover around the threshold, which would cause the
output to turn on and off rapidly. This setting helps to prevent that by creating a dead band below the
threshold before the output turns back off again.
Additional condition
• No additional condition - only a single condition is used
• Or - output triggers if either condition 1 OR condition 2 is met
• And - output triggers only when condition 1 AND condition 2 are both met
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7.8.21 Generic PWM outputs
The Generic PWM system allows up to six independent open-loop PWM (pulse width modulated) or
on/off outputs. The duties are programmed through an 6x6 table of rpm vs. Y-axis. For the Y-axis you
can choose from MAP, %baro, TPS, MAF load, battery voltage, CLT, or MAT. The output is typically
used to drive a solenoid valve (PWM mode) or relay (on/off.) PWM is a method that pulses an output
on and off, the on-time percentage (duty) is variable, this allows a valve to "float" in-between closed
and open for variable flow rates.
• Enable generic PWM - Turns this PWM channel on or off
• Output port/pin - Selects the output pin to use
• On-off or variable - On/off or variable PWM output
• On above duty - For on/off mode, duties in the table above this value turn the output on.
• Off below duty - For on/off mode, duties in the table below this value turn the output off. (Leave
a gap to prevent chatter.)
• Frequency - For variable outputs, this sets the frequency to pulse the output channel.
• Load Y axis - Choose from MAP, %baro, TPS, MAF load, battery voltage, CLT, MAT for the
Y-axis of the table.
• Table or Curve - You can use a 3D table of load and RPM or a 2D curve with just the load to
determine the output.
• CLT/MAT units - This settings chooses the temperature scale in use. It can only be set through
the "Generic Sensors" menu.
7.8.22 Generic Closed Loop outputs
The MS3-Pro has several predefined closed loop functions, such as idle speed, fuel pressure, and
boost control. For other functions that can use closed loop, the MS3-Pro has a generic function.
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• Enable - Turns the generic closed loop function on or off.
• Closed loop PID type - This allows you to change which PID loop type is used. A Type B loop
has the P term react to changes in error, while a Type C load has the P term respond to changes
in the feedback input variable instead.
• Load Axis - Sets what variable is used for the load in the 3D table.
• Feedback Input Variable - This is the sensor input to target with the PID loop.
• Max Feedback Input - The highest value the loop can target.
• Min Feedback Input - The lowest value the loop can target.
• Control Output Port / Pin - The PWM output channel used to control the device.
• Frequency - The frequency used to pulse the output.
• Max Control Output - The highest duty cycle the PID loop can command.
• Min Control Output - The lowest duty cycle the PID loop can command.
• Control Interval - The time between updating the control output duty.
• P Term, I term, and D term - The gain terms used to control the PID loop.
• CLT / MAT units - If using a temperature input as the load or feedback input variable, you can
set this screen to display Celsius or Fahrenheit.
• Target Table - This is the target value which the closed-loop algorithm aims to match to the
feedback input by controlling the PWM output.
7.9 3D Tuning Maps
This menu allows alternate 3D views of tuning maps from other settings: Fuel, ignition, boost control,
and sequential injection timing. Each view has a set of mini gauges to help tune the map. You may
right click on the gauges and swap them to other values if you prefer to use a different gauge type.
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7.10 CAN bus / Testmodes
7.10.1 CAN parameters
The MS3-Pro’s CAN wires allow it to connect to other devices over a network that uses a simple two
wire connection. These devices can add inputs and outputs, or display information from other devices
on the CAN network. Here are some general notes; we plan to offer more detailed notes on exactly
how to use these settings with specific devices. You will only need to set this up if the MS3-Pro is using
the CAN network for data acquisition or to control remote outputs. You do not need to do anything
other then set the CAN ID to zero if using the MS3-Pro CAN network for an external dashboard or
other CAN device that is set up to automatically fetch data from the MS3-Pro.
The CAN network typically works by passing along sections of memory tables. So many of the
settings will deal with telling the MS3-Pro where the table is in memory and how to retrieve it.
7.10.1.1 Base data
• My CAN ID - the CAN ID of this MS3-Pro, normally left at zero.
Each device on the CAN network has its own unique ID, with the number zero reserved for the master
device. You may connect up to 14 extra devices to the MS3-Pro, so remote CAN ID numbers can be
from 1 to 14.
• Master Enable - Enables fetching data from expansion board via CAN. Setting to "Off" still
allows CAN-passthrough for tuning but turns off all other messages. This can be useful for
performing a firmware upgrade on a remote expansion board.
7.10.1.2 PWM polling The MS3-Pro can collect remote PWM or frequency based type input data,
from a VSS for example. Turning “Enable PWM polling” on enables capturing PWM (pulse/frequency)
from expansion board and selects either 16bit or 32bit data. Refer to your expansion board documentation for the appropriate setting.
• Remote CAN ID - the CAN ID of the remote board
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• Enable PWM polling - enable or disable this feature
• Remote table number for PWM data - varies by application
• Remote table offset for PWM data - varies by application.
• Remote clock - The clock on the remote device
• Remote prescale - If used a prescale divider
• Remote divider - If used a clock divider
7.10.1.3 Digital I/O This allows the MS3 to use up to eight remote on/off inputs (CANIN1-8) and
up to sixteen remote on/off outputs (CANOUT1-16). CANIN1 is bit 0 from the remote input port and
CANIN8 is bit7. CANOUT1 is bit 0 from the first remote output port and CANOUT8 is bit7. CANOUT9
is bit 0 from the second remote output port and CANIN16 is bit7.
• Remote CAN Id - the remote CANid to fetch from
• Table - the remote table number
• Enable input port - enable remote input port
• Offset - the offset number in the remote table
• Enable output port - enable remote output port
• Offset - the offset number in the remote table
7.10.1.4 PWM outputs MS3-Pro can command PWM outputs on remote CAN devices. You will
need to refer to your CAN device’s documentation for the appropriate settings to use.
• Enable PWM outputs - Enables sending PWM/pulsed outputs to expansion board.
• Remote CAN ID - Enables sending PWM/pulsed outputs to expansion board.
• Table - Enables sending PWM/pulsed outputs to expansion board.
• Offset - Data offset on the expansion board used for PWM outputs.
• Forde duty to 0-255 - Normally, PWM duty cycles read on a 0-100% scale. However, some
remote devices require an 8 bit, 0 to 255 scale. This setting enables the 8 bit scaling.
7.10.1.5 Analog (ADC) inputs over CAN This allows additional analogue inputs to be captured
from remote CAN devices and used with most MS3 features. The code allows up to 24 remote CAN
ADCs. The dropdown menus (e.g. EGT) allow you to select either a local ADC or a remote CANADC.
Before attempting to use the chosen CANADC, you need to enable it on this CAN settings menu. Due
to data sizes, the CANADCs are configured in groups of four. The exact table and offset numbers are
specific to the configuration of the remote device.
• Enable ADC polling - enable or disable the feature
• CAN ADC 1-4 - enable or disable this group.
• CAN Id - the remote CANid to fetch from
• Table - the remote table number
• Offset - the offset number in the remote table
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7.10.2 CAN broadcasting
This if for interfacing with simple gauge circuits that need the MS3-Pro to actively send out information at regular intervals. You can specify how often to transmit this information. Currently, the
MS3-Pro can broadcast RPM or coolant temperature data, and supports a handful of European car
dashes. Future firmware upgrades are likely to support additional devices.
7.10.3 CAN VSS, gear, EGO
These settings are for CAN enabled devices that provide the MS3-Pro with wideband O2 sensor,
speed, or gear information. Refer to your device’s documentation for how to configure it with the
MS3-Pro.
7.10.4 Real time clock
The MS3-Pro has a built in clock that lets you apply a date stamp to data logs.
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• Enable real time clock - You may set this to “On-board” to use the MS3-Pro’s internal clock, or
“CAN” to use an external, CAN enabled device such as a GPS module.
• Trim - This is measured in parts per million, and lets you adjust the clock if you find it is running
fast or slow.
The Remote CAN ID, Table, and Offset devices are only used if you are using a clock on a CAN device
instead of the MS3-Pro’s internal clock. If you are using a remote clock, refer to your CAN device’s
documentation for how to configure this,
The “Set MS3 Time to Now” button will synchronize the MS3-Pro internal clock to your computer’s
clock.
7.10.5 Check Engine Light
The MS3-pro has a sensor validation system that can sanity check the sensor inputs. If the sensor
appears to be malfunctioning, then it can switch on a Check Engine light. Additionally, limited operating strategies (limp modes) can be enabled. The aim of these settings is firstly to warn you of
a failed sensor that could cause poor or damaging engine operation and secondly, through the limp
modes, to allow some engine operation even with the failed sensor. The checking scheme varies
slightly for each sensor. Most sensors are checked against minimum and maximum possible values
that can occur if the wire breaks or is shorted to ground or 5V. The other criteria is minimum and
maximum fluctuation - this is to detect a stuck or wildly flailing sensor. All of these parameters are
engine specific, and you will need to dial them in for your installation.
The sensor validation often works with ADC counts. ADC stands for analog to digital converter,
and refers to a circuit in the MS3-Pro’s processor that converts an analog voltage to a digital readout.
The MS3-Pro converts sensor readings into a 0 to 5 volt signal that goes to the processor, and the
processor uses a 10 bit converter to turn this into a value that ranges from 0 at 0 voltage to 1023
at 5 volts. Usually, these ADC counts are hidden from the user - you’re more interested in what the
sensor reading actually means than a raw number. However, with sensor diagnostics, you’ll be looking
at the ADC count directly, since we’re looking at establishing when a signal doesn’t mean anything
other than that your sensor isn’t working. For starting settings, try a minimum ADC value of 5, and a
maximum ADC value of 1018. You can use Status 5 to data log the actual ADC readings.
The fluctuation units are a bit arbitrary; we recommend data logging the values to see what is
normal, and using that to set the minimum and maximum values.
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• Sensor checking - Enables or disables this system
• Light output - Selects an optional output for the Check Engine Light. Recommended. Note
that this can share a channel with the AFR Safety warning light.
• CEL Solid / Flash Codes - You can have the Check Engine light stay on, or transmit flash
codes.
• Light When Not Running - Specify if the Check Engine light should be off or on when the
engine RPM is at zero.
• Ignore fluctuations for first - The number of seconds that sensor fluctuations are ignored after
startup. This is to allow conditions to settle down and avoid false alarms.
• MAP sensor check - Enable or disable checking of the MAP sensor input.
• Minimum ADC - minimum valid ADC reading for the MAP sensor
• Maximum ADC - maximum valid ADC reading for the MAP sensor
• Minimum Fluctuation - minimum fluctuation during smooth running
• Maximum Fluctuation - maximum fluctuation during operation
The minimum fluctuation setting is likely the most useful setting here, as it can be used to detect
a failed or "stuck" sensor, or if a hose fell off. A correctly operating MAP sensor will not produce a
perfectly flat value on a running engine.
• MAT sensor check - Enable or disable checking of the MAT sensor input.
• Minimum ADC - minimum valid ADC reading for the MAT sensor
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• Maximum ADC - maximum valid ADC reading for the MAT sensor
• Maximum Fluctuation - maximum fluctuation during operation
• CLT sensor check - Enable or disable checking of the CLT sensor input.
• Minimum ADC - minimum valid ADC reading for the CLT sensor
• Maximum ADC - maximum valid ADC reading for the CLT sensor
• Maximum Fluctuation - maximum fluctuation during operation
The CLT sensor should be smooth in operation; the max fluctuations can be used to detect a fault.
You’re likely to see a lower maximum fluctuation value here than on most other sensors. Not only do
you have a sensor with a fairly large thermal mass, but the coolant and engine block aren’t going to
change temperature very quickly.
• TPS sensor check - Enable or disable checking of the TPS sensor input.
• Minimum ADC - minimum valid ADC reading for the TPS sensor
• Maximum ADC - maximum valid ADC reading for the TPS sensor
• Maximum Fluctuation - maximum fluctuation during operation
For the TPS, the minimum and maximum ADC values are the more likely ones to detect a fault. You
can view the ADC counts at closed and wide open throttle under the Tools menu when you select
Calibrate TPS. A good starting point is a minimum ADC that is 10 counts below the closed throttle
calibration and a maximum ADC 10 counts above the full throttle calibration.
• Battery check - Enable or disable checking of the battery voltage input.
• Minimum voltage - minimum acceptable voltage reading
• Maximum voltage - maximum acceptable voltage reading
• Maximum Fluctuation - maximum fluctuation during operation
This can be used to warn of charging system faults or ground issues causing excessive voltage noise.
• EGO1 sensor check - Enable or disable checking of the EGO1 sensor input.
• Minimum ADC - minimum valid ADC reading for the EGO1 input
• Maximum ADC - maximum valid ADC reading for the EGO1 input
• Minimum Fluctuation - minimum fluctuation during smooth running
• Maximum Fluctuation - maximum fluctuation during operation
The fluctuation settings are key to detecting a failed O2 sensor. Many wideband controllers will get
"stuck" if the sensor fails, although appearing to show a valid AFR reading. Combined with closedloop EGO or autotuning, this can be troublesome without this detection scheme. Other controllers
allow an “out of range” voltage output - match the min/max ADC readings to capture this.
• Sync-loss check - Enable or disable checking of sync losses to troubleshoot crank or cam
sensors.
• No. sync losses allowed - how many recorded losses of tach-in synchronization are allowed
before setting the CEL. (During normal operation, you may see one or two sync-losses during
startup. Beyond that, there is a problem with your RPM input wiring or configuration.)
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• EGT sensor check - Enable or disable checking of the EGT sensor inputs.
• Minimum EGT - minimum valid EGT while engine is running
• Maximum EGT - maximum valid EGT while engine is running
• Minimum Fluctuation - minimum fluctuation during smooth running
• Maximum Fluctuation - maximum fluctuation during operation ()
The exhaust gas temperatures are not checked immediately after startup, so the minimum temperature can be set to 200C to detect a dead cylinder or faulty sensor. The maximum will depend on your
engine. N/A could be around 900C, boosted perhaps 1000C.
• Flex sensor check - Enable or disable checking of the Flex sensor input. (An error condition
will be triggered if the frequency on the flex input is outside of the set range.)
• status5 input - Specifies which sensor details are logged in status5 in the data log fields.
• status5 shows - If set the fluctuation, the value of status5 is the fluctuation number the code
calculates and compares to the minimum or maximum for each chosen sensor. e.g. Set this
to MAP and then enable ’status5’ on your dash or view in a datalog. Allow the engine to idle
and observe the lowest number. You can then set the MAP minimum fluctuation to some value
LOWER than this number. If the MAP input becomes too stable (e.g. the hose falls off), then
the alarm will be raised. If set to ADC counts, this shows the raw analog to digital conversion
reading of the sensor.
7.10.5.1 Check Engine codes The Check Engine light can be set to flash codes. These codes
also show up as CELStatus in the data logs. The codes are as follows:
• 2: MAP sensor fault
• 3: MAT sensor fault
• 4: CLT sensor fault
• 5: TPS fault
• 6: Battery voltage fault
• 7: O2 sensor fault
• 8: Loss of sync (crank or cam sensor)
• 9: EGT sensor fault
• 10: Flex fuel sensor fault
• 11: MAF sensor fault
• 12: Knock sensor fault
• 13: Cam sensor fault, engine still has sync but is running in semi-sequential
• 14: Oil pressure out of range
• 15: Fuel pressure sensor out of range
• 16: EGT safety shutdown triggered
• 17: AFR safety shutdown triggered
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7.10 CAN bus / Testmodes
7 ADDITIONAL ITEMS: BEYOND BASIC FUEL AND IGNITION CONTROL
7.10.6 Limp Mode
After detecting a sensor fault, the MS3-Pro can take action based on what it has detected - either
substitute a replacement sensor reading, ignore the sensor, or use an alternate sensor. The limp
mode can also impose a low rev limit and limit boost. The purpose of the limp mode is to get you
home or off the race-track etc. without damaging the engine. Certain faults will cause poor operation;
the aim is to allow some operation in preference to no operation.
Here is what action the MS3-Pro can take in response to sensor failures.
• MAP sensor failure: The MS3-Pro can either continue running on the MAP sensor but apply
the rev and boost limits, or it can substitute a fallback MAP table that guesses the MAP reading
based on throttle position and RPM.
• MAT sensor failure: Substitutes a fixed sensor reading.
• CLT sensor failure: Approximates a coolant sensor reading based on time after start. Note - It’s
a good idea to set the warmed up value to a point high enough to turn your cooling fan on, if the
MS3-Pro is controlling the fans.
• TPS failure: Disables TPS based acceleration enrichment and assumes a zero TPS value.
• EGO sensor failure: Turns off all closed loop O2 correction.
• Flex fuel sensor failure: Uses the fallback timing addition and fuel multiplier defined on the flex
fuel screen.
• MAP triggers limp mode - whether a MAP fault triggers limp mode
• Use fallback MAP table - if this is enabled, the MS3-Pro uses a table to approximate the likely
engine MAP reading if the MAP sensor fails.
• MAT triggers limp mode - whether a MAT fault triggers limp mode
• Fallback MAT - replacement MAT value
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• CLT triggers limp mode - whether a CLT fault triggers limp mode
• Fallback cold CLT - replacement initial CLT value
• Fallback warmed up CLT - replacement final CLT value
• Time to warmup engine - time taken to blend from cold to warm value (simulating a warmup
cycle)
• TPS triggers limp mode - whether a TPS fault triggers limp mode. TPS based acceleration is
disabled if TPS is faulty.
• Batt triggers limp mode - whether an out of range battery voltage reading triggers limp mode
• EGO triggers limp mode - whether an EGO fault triggers limp mode
• Flex triggers limp mode - whether a Flex fault triggers limp mode EGT triggers limp mode whether an EGT fault triggers limp mode
The settings below are applied when any sensor triggers the limp mode.
• Limp rev limit - the hard fuel cut rev limiter when in limp mode
• Limp boost limit - the boost limit when in limp mode. Typically, this will be no boost to prevent
engine damage in unknown conditions.
• Limp boost valve duty - forces boost valve1 to a set duty in limp mode.
• Limp boost valve2 duty - forces boost valve2 to a set duty in limp mode.
• Limp retard timing by - retards timing by the set amount in limp mode.
7.10.7 Fallback MAP table
In the event of a MAP sensor failure, the MS3-Pro can use a synthesized MAP value based on
TPS and Rpm. This will be less accurate than the real MAP reading, but the aim is to allow some
driveability in the absence of a real sensor reading before the root cause failure is fixed.
The initial vales for this table can be derived from datalogs comparing MAP, RPM, TPS while
driving. You can use MegaLogViewer’s scatter plot feature to see what MAP reading is common for
the throttle position and RPM range in a data log; the shape of the scatter plot will be close to the
table required.
To test and tune this table, unhook the MAP hose and wait until “Limp Mode” engages. Then this
table will be operative and you can tune.
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7.10.8 Output test mode - Inj / spark
The test mode allows direct control of the coils and injectors. Used by accident this could cause
flooding of the engine and potential damage. Therefore a special initialization method is required to
enable it. Do not attempt to test injectors or coils on a running engine. Before testing injectors on
a engine be sure to depressurize the fuel rail - this can be achieved by unplugging the fuel pump
while the engine is idling. Unless you are flow testing injectors on a flow-bench, you may well want
to remove the fuel pump fuse during all of this testing. Before using the test mode, ensure that you
have already configured the correct number of cylinders and type of injector and spark output etc. i.e.
if you want to test 8 cylinder COP mode, you need to have configured that already.
First ensure that you are key-on, engine-off. (Or that RPM is set to zero on the stim if bench
testing.) In this condition the “Enable Test Mode” button will be available. Click the button to enable
the test mode.
7.10.8.1 Fuel Pump Clicking Fuel Pump On will enable the fuel pump output and light the "Ready"
indicator on TunerStudio.
Clicking Fuel Pump Off will disable the fuel pump output and turn off the "Ready" indicator.
7.10.8.2 Coils The coil test mode is useful to confirm you have the coils wired correctly and to
check dwell settings. (Do be careful as ignition coils put out a potential lethal voltage. Typically
30,000V or more.)
To enable coil testing:
1. Choose the desired output interval (the estimated RPM equivalent is shown below.)
2. Set Coil testing mode to One
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3. Choose which coil to test e.g. Coil A
4. Choose your dwell time in milliseconds. Start low. e.g. 2.5ms.
5. If your coils are powered via the fuel pump relay as is recommended, set the fuel pump to On.
6. With valid settings entered, the Start button should be active - click it.
7. When finished, click Stop.
If the coils get hot or your coil fuses pop, then you almost certainly have a basic settings mistake with
output polarity. Turn off power immediately and re-visit those settings.
The Coil testing mode called Sequence runs the coils in sequence up to the chosen coil. So if you
have four coils and selected Coil D and Sequence then the test mode will repeatedly fire Coil A, then
Coil B, then Coil C, then Coil D in turn. Note that the test mode does not allow dwell periods to overlap
in the sequence mode, unlike normal operation where the dwell periods overlap as required. (This is
why traditional V8 distributor spark was weak at high revs - there was not enough time to charge the
single coil between sparks.)
7.10.8.3 Injectors The coil test mode is useful to confirm you have the injectors wired correctly
and to experiment with opening times, PWM settings or to measure flow rate if you have an injector
test bench setup. (Using flammable liquids while testing is hazardous and can lead to serious fires.
Non-flammable injector test liquid is available.)
If your injectors are fitted to the engine you MUST NOT run the test mode with fuel pressure,
or you will fill your engine with fuel! Remove the fuse from your fuel pump and depressurize
the line first.
When semi-sequential is enabled, the injectors will fire in pairs. To test individually, temporarily set
Sequential to Off.
To enable injector testing:
1. Choose the desired output interval (the estimated RPM equivalent is shown below.)
2. Set Injector testing mode to One
3. Choose which injector to test e.g. Injector A
4. Choose your pulsewidth time in milliseconds.
5. If your injectors are powered via the fuel pump relay as is recommended, set the fuel pump to
On.
6. For functional testing, set the total number of injections to 65535 (the maximum), or for flow
testing use your chosen number.
7. With valid settings entered, the Start button should be active - click it.
8. The number of injections gauge will count down and stop at zero.
9. To stop testing sooner, click Stop.
When you have finished using the test mode, close the test mode window and power off the MS3-Pro.
If you disconnected you fuel pump, reconnect it now.
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7.10.9 Output test mode - I/O
This allows you to test some of the on/off and pulsed outputs in a controlled manner. As with the other
tests, be cautious - this mode allows you complete control over the outputs; it is up to you to ensure
that doesn’t cause any damage.
First ensure that you are key-on, engine-off. In this condition, the “Enable Test Mode” button will
be available. Click the button to enable the test mode. For each of the outputs you can select the
following:
• Off - turns the selected output off.
• On - turns the selected output on.
• Pulsed - pulses the output at the selected frequency and duty. (Not available on the fuel pump.)
Except for the Tach channel, all of these outputs are ground switched, so you will not be able to see
their status with a volt meter. Use a small test lamp or test LED connected between 12V and the
output, if you are not using them with a solenoid or the actual device you will be driving.
7.10.10 Output test mode - idle valve
The idle valve test mode can be used with the engine running or stationary. Note that with a PWM
idle valve you may need to run a temporary fused 12V supply to the valve if you normally take power
from the fuel pump relay and are testing with the engine off. You need to have enabled idle control
before this is available.
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7 ADDITIONAL ITEMS: BEYOND BASIC FUEL AND IGNITION CONTROL
• Idle Valve Homing Steps - This only applies to stepper idle valves. This setting determines how
many steps the motor should move during homing to ensure it has reached the home position.
The number needs to be large enough to close the valve from any unknown starting position.
(This is because there is no position on most automotive stepper IAC valves.)
• Idle Valve Step - the desired valve position if using a stepper IAC valve. Larger numbers should
give a more open valve and higher rpm.
• PWM idle duty% - the desired valve position if using a PWM IAC valve. Larger numbers should
give a more open valve and higher rpm.
(Note that some Bosch rotary PWM valves valves feature a failsafe mode so that zero flow is at a
midpoint, such as 20% duty,; above that the valve operates as expected where more duty gives more
airflow. Below this specific point is a failsafe mode that allows airflow even if there is no control signal.
This is readily observed during test mode.)
There are three control buttons:
• Enable Test - Home Position - for stepper idle valves, this moves the valve through the number
of homing steps back to the home position. (If it doesn’t get all the way back to the stop, increase
the number of homing steps.) The valve will move to the run position shortly afterwards.
• Enable Test - Run Position - enable test mode where the steps or duty setting controls the
valve position
• Enable Test - In / Out Cycle - Moves the valve continously between the home and run position.
• Stop Testing - disable test mode and allow normal idle control to operate.
7.10.11 Injector Sequence Testing
This screen allows you to switch in and out of sequential injection on the fly to evaluate how the engine
runs in different modes. You can make an engine running full sequential drop down to semi sequential
or batch fire, or make an engine running semi sequential swap to batch fire.
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7 ADDITIONAL ITEMS: BEYOND BASIC FUEL AND IGNITION CONTROL
Note that Full Sequential and Semi Sequential modes only work if the engine is already configured
to run in these modes. Clicking Stop Testing reverts to the existing settings.
7.10.12 Inj / Spk Disabling Test Mode
Looking for a dead cylinder? Instead of unplugging the injectors or coils to check for a cylinder that’s
not working, the MS3-Pro lets you shut down individual cylinders through TunerStudio. Note that you
need enough inputs for full sequential operation to allow for disabling cylinders. Click the cylinder
buttons to disable the coil or injector associated with that cylinder.
7.10.13 Special options
These are highly specialized options; most users will not need to ever touch them.
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7.10 CAN bus / Testmodes
7 ADDITIONAL ITEMS: BEYOND BASIC FUEL AND IGNITION CONTROL
• Pulsewidth Scaling - Setting the pulsewidth scaling reduces the pulse width resolution, but
enables four times the normal maximum pulse width (normally, this is limited to 65 milliseconds).
Usually, you would use this feature on very large, low RPM engines, where the injectors are
sized exclusively for operation below 2000 RPM. You also need to enable “PW4X” in Project
Properties when using this feature.
• Digital switched 12V In Pulldown - causes the voltage on this pin to default to 0 volts. This
ordinarily should not be changed unless you have modified the MS3-Pro internally or connected
a highly unusual circuit to this input.
• Log Trigger Times to Sensors 9-16 - This enables an experimental feature to record engine
trigger times to sensors9-16 to monitor per-cylinder effort. Only for developers.
The SpkAdj values can place limits on a remote device modifying the spark timing over CAN. Currently, the most likely device to do this is a transmission controller; the MicroSquirt transmission
control firmware can retard spark while shifting to reduce wear and tear on the transmission. Other
devices may also adjust timing in the future.
• Maximum SpkAdj Value - Sets a limit on the maximum adjustment a remote device can apply
to the ignition timing. This is a positive number, meaning advance.
• Minimum SpkAdj Value - Sets a limit on the minimum adjustment a remote device can apply
to the ignition timing. This is a negative number, meaning retard.
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8 TROUBLESHOOTING AND DATA LOGGING
8 Troubleshooting and Data Logging
8.1 Resets
A reset is when a disruption in power or a spike in voltage causes the processor to briefly shut down.
This will cause the engine to hiccup while running, and will display a couple other symptoms. The
MS3-Pro will reset when it is powered up, and this is the right time for it to reset. Having it reset on a
running engine, however, is something you’ll want to fix right away.
• The MS3-Pro will briefly disconnect from the laptop or other devices on USB or RS232.
• Data logs will indicate a “Mark (number) - RESET”.
• The SecL count will drop to zero.
The last item is a key part for spotting true resets in a data log. If the engine hiccups, but the SecL
count does not drop back to zero, you’ve got something else, such as a fuel cut, loss of RPM signal,
or other issue. If it’s a real reset, here are the items we recommend checking first.
First, make sure the MS3-Pro has all ground wire used, and grounded to the engine block, cylinder
head, or negative terminal of the battery. Chassis grounds can have issues caused by rust or points
where current runs through nothing but a thin spot weld.
Check where the MS3-Pro is getting power from a clean source - ideally, you’ll want it to be
powered off the battery, with no devices that draw significant current getting power from the same
feed. Many resets come not from EMI / RFI interference, but from something like an ignition coil or
fuel pump injecting voltage spikes into the power feed.
Make sure that you are using resistor type spark plugs, good spark plug wires (if you’re not running
coil on plug), and that the spark plug wires are not within one inch of any wires going to or from the
MS3-Pro.
8.2 Capturing data logs
Data logs allow recording information from the engine for later analysis. These can help you troubleshoot your fuel tables, sensor readings, and more. You can record data logs from a laptop or with
the MS3-Pro’s built in SD card. All of these are accessible from the Data Logging menu.
Use MegaLogViewer to play back the data logs.
8.2.1 Data logging with a laptop
To start a data log, go to the Data Logging menu and select Start Logging. TunerStudio will prompt
you for a file name. You can go with the default date stamp, or enter a more descriptive name. The
data log starts when you save the file. It stops when you either select Stop or close TunerStudio.
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8 TROUBLESHOOTING AND DATA LOGGING
Burst logging mode shuts down gauge updates and several other features. We don’t recommend
using this except for logging on extremely slow devices.
Automatic logging enables TunerStudio to start or stop logging based on ECU variables or math
expressions. For example, you can set TunerStudio to start logging when the RPM goes over a certain
value, or when the SD card logging reports an error.
8.2.2 Data logging with the SD card
The MS3-Pro comes with an SD card built in for internal logging. Selecting SD card datalogging from
the menu brings up this screen:
• SD card logging
– Disabled - turns off the SD logging feature
– Insertion - Logs at any time the MS3-Pro contains an SD card. We do not recommend
inserting or removing the card with the MS3-Pro powered up.
– Button - logging is controlled by a push button
– Trigger - Logging is triggered by RPM or throttle position.
• Datalog button - selects the input pin used for the button if used.
• Trigger - Specify whether the log is to be triggered by RPM or throttle position.
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8 TROUBLESHOOTING AND DATA LOGGING
• LED indicator - selects the output used for the optional LED indicator. This output is on when
SD card data logging is active.
• Log data block size
– 64 byte is the most common setting
– 64 byte + stream allows the simultaneous recording of data and a 8kHz mono sound input.
This could be used as a commentary during a datalog such as position on a racetrack or
notable incidents in the log. Presently the tuning software does not support extracting this
audio data.
• Interleave GPS Data - Enables the recording of interleaved GPS data. Requires a CAN connected GPS module.
• Sampling
– Timed - a data sample is taken at predefined time interval - this is the most common option
– every tooth, every cycle - for special logging and at low engine speeds, these options take
a data sample at these events
• Sample interval - how often to take a data sample. 3ms is the fastest supported, but many cards
will only sustain 5ms before you start getting small gaps in the logs. See the utilities section for
speed testing. The frames per second that this sample interval works out to is displayed below
this setting.
• Log file max duration - how long each datalog should be. The files are always created full size
and fill up the allocated space during logging. If the log file is filled, a new file is started. If you
turn off the power to the MS3-Pro (which is safe to do during a log) the log will be there and will
show full size. When the log file is extracted, the unused part of the allocated file will be ignored.
(Note, it is impossible for the MS3-Pro to set the file length or otherwise "clean up" the log file in
this case because there is no power and the processor is off !) A result of this is that all log files
on the SD card will appear the same size.
• Stream input - where the 0-5V audio input is connected, if using the stream option.
• SPI Comms Speed - Allows you to adjust the speed if you have swapped the SD card for one
that does not run at normal logging speed.
Log field selection
The field selector allows you to choose which data fields you want to log. Because of the compact
datalog format, only 64 bytes are available total, so you need to pick the data that you find most
critical. To add a field, highlight it on the left and then click on > to move it to the right. To remove a
field, highlight it on the right and then click on < to move it to the left.
Button usage
When Megasquirt-3 powers up it will create an empty datalog file ready for logging. Press and
hold the button for over half a second to start a log. A quick press of the button will end the log. When
extracting the log files you will likely find a blank log file on the card after your real logs, this is normal.
LED flash codes
• Off - SD logging not active
• On (solid) - Ready but not logging
• Fast flashing - Initializing card
• Slow flashing - Logging
• Pause, sequence of flashes - error code (See Error codes section)
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8.2 Capturing data logs
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8.2.3 Downloading SD data logs
The Browse / Import SD Card option on the Data Logging menu brings up the following screen.
The screen shot above shows the menu without a MS3-Pro connected. If you have data logs on
the SD card, they will appear in the list at the right hand side. Click the green “down arrow” button to
save the selected logs to your computer. The middle button will reload the list of files, and the red X
will delete the selected files.
8.2.4 SD card error codes
You can view SD card error codes by right-clicking on a gauge and swapping it to an “SD error” gauge.
Some error codes are not used.
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8.2 Capturing data logs
Error number
0
1
2
3
4
5
6
7
8
9
10
12
13
14
15
16
17
18
20
21
22
23
24
25
26
28
29
30
31
32
8 TROUBLESHOOTING AND DATA LOGGING
Error name
No error
Sending clock error
Idle error
Init error
Set block size
Request CSD
Error reading MBR
MBR end marker not found
No partition 1 defined
Error reading partition boot sector
Error reading directory
Error reading file allocation table (FAT)
Error reading FAT continuation sector
Error writing FAT
Error reading directory
Error writing directory
Error writing log sector
Unsupported FAT type (not FAT16)
SDHC detection error
VCA check pattern failed
VCA voltage rejected
Operation Condition Register (OCR) error 1
OCR2
OCR3
OCR4
Error processing CSD
Write failed
Directory full
Can’t find space in FAT
Looks like VBR but not valid
Notes
SD logger is working correctly.
Possible card fault. Try replacing SD card.
Possible card fault. Try replacing SD card.
Possible card fault. Try replacing SD card.
Possible card fault. Try replacing SD card.
The SD card being used is an unsupported type.
Erase files and reformat SD card.
Erase files and reformat SD card.
Erase files and reformat SD card.
Possible card fault. Try replacing SD card.
Possible card fault. Try replacing SD card.
Possible card fault. Try replacing SD card.
Possible card fault. Try replacing SD card.
Possible card fault. Try replacing SD card.
Possible card fault. Try replacing SD card.
Possible card fault. Try replacing SD card.
Possible card fault. Try replacing SD card.
Erase files and reformat SD card.
Try reformatting SD card.
Possible hardware fault. Try replacing SD card.
Possible hardware fault. Try replacing SD card.
Possible hardware fault. Try replacing SD card.
Possible hardware fault. Try replacing SD card.
Try reducing data logging speed.
Possible card fault. Try replacing SD card.
Full SD card - delete data logs.
Full SD card - delete data logs.
Erase files and reformat SD card.
8.2.5 Data log bit fields
Several of the data log fields are a bit code. To decypher a bit field, you need to determine what
combination of numbers adds up to the final number. Do this by taking the first code number that is
smaller than the value displayed, subtract that, and repeat the process until you’ve used up all the
numbers. For example, suppose you have a CEL Status code of 15. Here’s what you would do.
• The highest number on the chart that is less than 15 is 8. TPS fault. So we have a TPS fault
present.
• Subtract 8 from 15, giving us 7. We’ll need to see what codes make up the 7.
• The next lowest value is 4. CLT sensor fault. So there is also a CLT sensor fault.
• Subtracting 4 from 7 gives us 3. So we have more codes to find.
• The nexts lowest number on the chart is 2. MAT sensor fault.
• Subtracting 2 from 3 gives us 1. This is the last code, a MAP sensor fault.
The above combination of faults is likely to be a problem with the VREF voltage or sensor return
wiring, if you run into this status in the real world.
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8.2 Capturing data logs
8.2.5.1 CEL status CEL status
128
64
32
EGT fault
RPM loss
AFR input
of sync
fault
This is the only 16 bit variable used.
32768
16384
8192
AFR
EGT
Fuel
shutdown
shutdown
pressure
fault
CEL status 2
128
64
32
Reserved
Reserved
Reserved
8 TROUBLESHOOTING AND DATA LOGGING
16
Battery
voltage
fault
8
TPS fault
4
CLT
sensor
fault
2
MAT
sensor
fault
1
MAP
sensor
fault
4096
Oil
pressure
warning
2048
Cam fault
1024
Knock fault
512
MAF fault
256
Flex fuel
sensor
fault
16
Reserved
8
Reserved
4
Reserved
2
Safety
shutdown
1
Water
injection
fluid low
2
Cranking
1
Ready
(RPM or
fuel pump
on)
8.2.5.2 Engine “Engine” is a single status field with many basic information items.
128
64
32
16
8
4
MAP decel MAP accel TPS decel
TPS accel
Warmup
Afterstart
fuel cut
enrichfuel cut
enrichenrichenrichment
ment
ment
ment
8.2.5.3 Port codes These fields read the actual status of the input and output pins at the processor. Note that the ports that drive the fuel and ignition outputs, cam / crank inputs, and PWM signals,
may not be sampled fast enough to tell for certain if these outputs are active.
Port A
128
64
32
16
8
4
2
1
Injector H
Injector G
Injector F
Injector E
Injector D
Injector C
Injector B
Injector A
Port B
128
64
32
16
8
4
2
1
Spark H
Spark G
Spark F
Spark E
Spark D
Spark C
Spark B
Spark A
Port EH
128
64
32
16
8
4
2
1
Digital
Digital
Fuel pump
Digital
switched
switched
switched
12V in
in 2
in 1
Port K
128
64
32
16
8
4
2
1
Internal
Digital
Internal
Tach out
switched
in 2
Port MJ
128
64
32
16
8
4
2
1
Internal
Stepper
Internal
Internal
Internal
Internal
Stepper
Stepper
enable
out 2
out 1
The stepper enable output is on whenever either stepper output is active.
Port T
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8.3 Tooth / trigger logger and troubleshooting RPM8issues
TROUBLESHOOTING AND DATA LOGGING
128
-
64
Digital
frequency
in 3
32
Digital
frequency
in 2
16
Digital
frequency
in 1
8
Injector J
4
CMP
2
Injector I
1
CKP
8.2.5.4 Status codes These describe which features are currently active.
Status 1
128
64
32
16
8
4
2
1
Full RPM
Spark
Fuel table
Sync latch
RPM sync
Config
Lost data
Need to
sync
table
switching
error
burn
switching
settings
Status 2
128
64
32
16
8
4
2
1
Closed
Overboost
Spark cut
Flat shift
Launch
Launch
Nitrous
Nitrous
loop idle
protection
active
control
control
stage 2
stage 1
active
armed
active
active
Status 3
128
64
32
16
8
4
2
1
Launch on Sequential
Soft rev
3 step
Test mode
3 step
T log
Fuel cut
shift cut
limit
armed
active
active
Status 4 and 5 are development fields. You can set the Check Engine functionality to use Status
5 to record sensor ADC counts or input fluctuation levels.
Status 6
128
64
32
16
8
4
2
1
MAP
Fan on
Idle
Idle VE
AFR
AFR
EGT
EGT
sample
advance
table
shutdown
warning
shutdown
warning
error
mode
mode
Status 7
128
64
32
16
8
4
2
1
Limp
Check
A/C on
Knock
VVT4 error VVT3 error VVT2 error VVT1 error
home
engine
detected
mode
light
Status 8
128
64
32
16
8
4
2
1
Reserved
Reserved
VSS
VSS
PW 4X
Water
Spark
Injector
based
launch
mode
injection
disable
disable
launch
lockout
enabled
low
test mode
test mode
8.3 Tooth / trigger logger and troubleshooting RPM issues
Certain conditions such as electrical noise can cause the MS3-Pro to lose sync with the engine
position. This is called a sync loss event or a sync error. Common symptoms of this include:
• Feels like a misfire or a false rev limiter
• RPM in datalog suddenly drops to zero
• RPM in datalog suddenly spikes up
• "Lost sync count" increments while "SecL" counts up normally. (NB. If SecL suddenly drops to
zero this is a "reset"; see section 8.1.)
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Taking and reviewing a datalog is a required step for troubleshooting this. This datalog extract below
(viewed in Megalogviewer) shows the rpm (yellow trace) dropping to zero and at the same time the
"Lost sync count" increases. The "Lost sync reason" shows reason code 2.
8.3.1 Lost sync numbers
The MS3-Pro can report several different lost sync reasons in the data logs. Most of these simply
show that there’s a problem and don’t particularly pinpoint where it is, but some are more specific
than others. In particular, if you get Lost Sync Reason 11 or 17 in a specific RPM band, try changing
the ignition input capture and /or second trigger active edge.
0 no problem
1 init error
2 missing tooth at wrong time
3 too many teeth before missing tooth (last)
4 too few teeth before missing tooth (last)
5 1st tooth failed test
6 nonsense input (last)
7 nonsense input (mid)
8 too many teeth before missing tooth (mid)
9 too few teeth before missing tooth (mid)
10 too many teeth before end of sequence
11 too few teeth before second trigger
12 too many sync errors
13 dizzy wrong edge
14 trigger return vane size
15 and 16 - EDIS SAW signal error
17 second trigger not found when expected
20 subaru 6/7 tooth 6 error
21 subaru 6/7 tooth 3 error
22 Rover #2 missing tooth error
23 420A long tooth not found
24 420A cam phase wrong
25, 26, and 27 pattern does not otherwise match 420A
28 Pattern does not match 36-1+1
29 36-2-2-2 semi sync failed
30 36-2-2-2 tooth 14 error
31 Miata 99-00 - 2 cams not seen
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32 Miata 99-00 - 0 cams seen
33 6G72 - tooth 2 error
34 6G72 - tooth 4 error
35 Pattern does not match Weber-Marelli
36 CAS 4/1 error
37, 38, and 39 Pattern does not match 4G63
40 and 41 Twin trigger error
42 Pattern does not match Chrysler 2.2/2.5
43 Pattern does not match Renix
44 Pattern does not match Suzuki Swift
45 and 46 Pattern does not match Vitara
47 Pattern does not match Daihatsu 3
48 Pattern does not match Daihatsu 4
49 Pattern does not match VTR1000
50 Pattern does not match Rover #3
51 Pattern does not match GM 7X
52 36-2-2-2 tooth 30 error
53 rc51 semi error
54 rc51 re-sync error tooth 6
55 rc51 re-sync error tooth 16
56 rc51 re-sync error tooth 18
57 fiat 1.8 tooth 0
58 fiat 1.8 tooth 3
59 fiat 1.8 tooth 6
60 fiat 1.8 tooth 9
61 36-1+1 first
62 36-1+1 second
63 QR25DE semi failed
64 QR25DE lost running sync
65 CAS360 running
66 NGC8 semi failed
67 LS1 semi failed
68 LS1 resync failed
69 YZF1000 resync failed
Having identified that you have a sync loss problem, you need to attempt to eliminate it. Check for
any basic problems:
• Loose sensor
• Loose cabling
• Sensor wires running close to spark plug wires or coils
• Slop in timing belt
• VR sensor wired backwards
• Fouled plugs causing misfire
• Non-resistor plugs
• Excessively rich mixture causing misfire
• Excessively lean mixture causing misfire
Having ruled out all those possible causes, you should enable some noise filtering. See the noise
filtering settings, section 7.3.5.
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8.3.2 Using the diagnostic logger
The tooth / trigger logger, accessible under TunerStudio’s Diagnostic tab, lets you visualize crank and
cam signals. It does not give you a voltage reading directly, but it will show you the state of the crank
or cam signal, either on or off, as it reaches the MS3-Pro’s processor. Use this to troubleshoot issues
with the MS3-Pro’s RPM input. There are several different modes. They work in a similar way:
The Logger Type setting selects which log type to use.
The Start, Stop, and Clear buttons work as youd expect.
The Open Log button lets you pull up previous logs.
To capture a log to a file, first click the Capture Log to File button. You will be prompted to save a
file. After you save the file, you may then start the log and collect data.
8.3.3 Tooth logger
This records the tach events that are received by the main tach input (crank) after any noise filtering.
The height of the bar on the screen represents pulse length. The taller the bar, the longer the pulse.
This one is useful for interpreting sync issues with a missing tooth type wheel.
Here’s one with a simulated 36-1 wheel.
In the above 36-1 screenshot you can see 34 normal teeth and the single long "missing" tooth.
Usually, the log isn’t quite as perfect. Here’s one from a real 60-2 crank trigger while cranking a motor.
In the above 60-2 screenshot you can see 57 normal teeth and the single extra long "missing"
tooth. The cyclic nature of the teeth is due to the engine speeding up and slowing down during cranking. The OEM has place the missing tooth in a good place to avoid confusion with the compression
effect. With poor choice it can be difficult for the code to reliably detect the tooth.
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8.3.4 Trigger logger
This records the "decoded" and filtered tach events and is one pulse per normal ignition event. In
most cases, this is not nearly as useful as the tooth or composite logger.
8.3.5 Composite logger
The basic tooth logger records enough information to analyze a typical missing tooth wheel on the
crank. However, if the engine uses both cam and crank sensors, then a new logging method is
required. This third composite logger records both crank and cam signals and under some circumstances it will record both edges of the input signal. It could be used as a crude two channel oscilloscope. The composite logger shows three signals.
• The green line at the top represents the cam signal.
• The blue line in the middle represents the crank signal.
• The red line at the bottom represents error pulses that do not fit the expected pattern.
This log shows Subaru 6/7. This is a single edged signal, so the visualization can only show a
point/line.
This log shows an example double edged signal with some noise.
Here is a screen shot of a simulated signal with a 24 tooth crank wheel and a 1 tooth cam wheel.
The crank signal is single edged and the cam signal is double edged.
8.3.6 Sync error logger
This is a variant of the composite logger. During normal engine operation it will show nothing at
all, but if a sync-loss event occurs (due to noise) it shows the tooth pattern that led up to the loss
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of synchronization. This allows you to pinpoint the problem without searching for the needle in the
haystack as would be the case trawling through large composite logs. To use this logger, it is usually
useful to capture to a log file. Tick the "Capture to log file" box and save the file name. Then start
the sync error logger and drive or ride around. (You can datalog at the same time.) When you have
finished, Stop the logger and un-tick the "Capture to log file".
8.3.7 Example logs
Here are some examples of how these logs look in the real world.
Here is a tooth log of a 36-1 trigger wheel on a V8 while cranking.
The same trigger setup, but at running speed. Note that the time on the teeth smooths out and
the effect of the compression is much smaller.
Composite log of the same engine running.
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The above picture shows a 60-2 crank wheel during cranking. Note that the missing tooth is three
times the height of the other tooth marks, instead of twice the height as on a 36-1.
Tooth log of 60-2 showing incorrect VR sensor wiring. Two somewhat long teeth instead of one
very long tooth. In this situation the engine might get sync some of the time. Test it by change input
capture polarity to Falling, if that helps then swap VR sensor wires and return input capture setting to
Rising.
Composite log of a Nippon Denso ignition with a 24 tooth cam wheel (on the crank input channel)
and a 1 tooth cam wheel.
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Noise issues on the same ignition type. More noise filtering can reduce this problem.
8.4 Communication issues
If the internal fuse F1 is blown, the MS3-Pro will not communicate - see section 3.5.1 for how to
replace the fuse. A good way to check if this may be an issue without opening the case is to check if
you have 5 volts on the VREF wire with the MS3-Pro powered up. If either internal fuse is blown, you
will see 0 volts on this wire.
Most other reported user problems are actually a computer setup problem, so follow these steps
to get your settings right. The MS3-Pro package comes with a serial (RS232) and a USB cable; you
may use either one to connect, but not (currently) both at one time. If your tuning computer has a
built in RS232 port, that should “just work.” The USB port will work correctly with most versions of
Windows, but sometimes you will need to set up driver software. Note that the MS3-Pro cannot be
powered through the laptop; it needs to have 12 volt power through its wiring harness before it will
communicate. The USB connection will still show up on a computer, but it will not be able to send or
receive data to or from the MS3-Pro.
8.4.1 USB driver software
The MS3-Pro USB connection uses an FTDI chipset with a Virtual COM Port (VCP) driver.
8.4.1.1 Windows drivers You may download the driver from this page on the FTDI website:
FTDI virtual COM port drivers
Having downloaded the driver, you should run it and the drivers should be installed. Then insert
the USB cable and when Windows asks for a driver, you should be able to follow the automatic install
process. Having installed the drivers, proceed with Device manager. There are several ways to do
this, and you may have a preferred way. If you don’t know how to do this, here are directions for
getting into the Device Manager for XP and Vista / Windows 7.
On Windows XP, right-click My Computer and select Manage. This will bring up the Computer
Management screen. Select the Device Manager from the list at the left.
For Vista or Windows 7, click the Start button and go to the Control Panel. From there, click
System and Maintenance, then click on the Device Manager from there. You may need to enter a
password.
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If you DO NOT see "Ports" listed in the devices, then you do not have any ports setup. This would
usually indicate either your forgot to plug in your USB-serial cable to the MS3-Pro, or there is a driver
problem. Usually the best solution to the driver problem is to unplug the cable, uninstall the driver,
and then re-install the driver.
Find the Ports section and click the [+] to expand. Then double-click on the port number.
On the Port Settings tab, set the baud rate to 115200, then click on Advanced.
Ensure that the COM port number is 9 or less. If not, change it - TunerStudio can find higher
numbered ports, but it will take longer to detect an MS3-Pro on a high numbered port. It is usually safe
to ignore any Windows warning about ports being in use unless you really do have a physical serial
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port or built-in modem. The port number you select here is the one you need to use in TunerStudio.
While on this page reduce the Latency Timer. 1 is normally OK. The default value gives very slow
serial.
Now [OK] all windows to close them and then close the Device Manager.
8.4.1.2 Linux drivers USB serial adapters are typically used as /dev/ttyUSB0. All recent Linux
kernels include support for the built-in FT232RL USB-serial adapter. You might want to use the lsusb
command to check that the adapter has been recognized. dmesg can be used to see what port
number has been assigned.
8.4.1.3 MacOS drivers Install the latest MacOS driver from the link below:
FTDI virtual COM port drivers
Then plug in the cable and power on the MS3. Either use Autodetect in TunerStudio or check the
/dev directory for a port such as /dev/cu.usbserial-XXXXX .
8.4.2 Additional diagnostics
8.4.2.1 Portcheck The Port Check program is a small file, portcheck.exe, included for Windows.
Port Check scans the available COM ports and sends them commands that will cause a MS3-Pro or
other ECU to display its signature. The example below shows it detecting an MS2 on COM port 1.
Note that to run Port Check, you will want any other programs that use the serial connection,
like TunerStudio, closed. Sometimes it will report ’“S”ing “S”’ on a port at both speeds. This usually
happens if it’s trying to check a mouse port or other port that sends back any character it receives
instead of sending new information.
8.4.2.2 Loading firmware One other way to test an MS3-Pro that is not communicating and does
not pass the port check program is to try reloading firmware. It is possible to corrupt the firmware
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in such a way that it does not respond to normal communications, but still responds to a command
to load firmware. In such a case, loading firmware can reset the MS3-Pro’s settings. If the MS3-Pro
has power and ground, and is putting out a 5 volt signal on VREF, but does not respond to other
communications tests, try this.
8.5 Loading or upgrading firmware
MS3-Pros ship with the latest firmware on them, but we anticipate upgraded firmware being available.
The firmware can also be reloaded if it has somehow been accidentally erased. The MS3-Pro must
be powered up when loading firmware, and you need to close any other programs that could use
serial communication, such as TunerStudio, Palm HotSync, or modem software. The firmware loader
installs with the CD.
8.5.1 Windows firmware loader
The download utility is text based. Browse to the directory where you extracted the zip and doubleclick on ms3loader_win32.exe Example:
The firmware loading program will launch. Follow the onscreen prompts. Note that when it prompts
you for the file to load, you will want to use the file named ms3pro.s19.
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A message level of 1 is fine for most installs. The higher levels of detail are only needed for
debugging problems.
Scanning ports automatically is usually your easiest option, but it is slightly faster if you specify
what COM port to use.
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At this point, specify a file name of ms3pro.s19 and press Enter.
Preserving these settings can take somewhat longer. After this, the loader will give you a summary
of your requests before loading firmware:
Once you confirm this, it will load the firmware.
If this takes long than ~45 seconds then you likely need to adjust the port settings of your USBserial adapter to reduce the latency setting.
8.5.2 Linux firmware loader
It is assumed you’ll be using the command line here.
1. Create a directory for MS3. e.g. mkdir ms3
2. A 32bit compiled command-line firmware loader for Linux is included in firmware zip.
3. Fetch the latest s19 and ini files in a zip from the Code file area and save into the ms3 directory.
Extract the zip.
4. cd to the correct directory and key in the following: ./ms3loader_linux32bit
The program runs the same as the windows version, so see above for an example of typical output.
Typically, you only need to check you serial comm port. You can usually just press Enter on the other
selection. When loading code for the first time be sure to answer "Y" to the First time loading question.
If this takes long than ~45 seconds then you likely need to adjust the port settings of your USB-serial
adapter to reduce the latency setting. For the FTDI built in device, try the following.
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echo 1 > /sys/bus/usb-serial/devices/ttyUSB0/latency
If you get a permissions problem trying to run the file, you likely need to make it executable (e.g.
chmod a+x ms3loader_linux32bit or through your graphical interface.)
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