Tuning your vehicle. Hondata K-Series
The Hondata K-Series Programmable ECU is a plug-in replacement for the factory ECU in Honda K-Series engines. It features a high-speed USB interface and allows you to edit fuel, ignition, and cam angle tables, adjust fuel trim (including individual cylinders), control rev limiter, and protect your engine from overboost and overheating. It supports alternate MAP sensors, VTEC set as a VTEC window, and nitrous control. You can also adjust for different sized injectors and use closed-loop and idle speed adjustments.
Advertisement
Advertisement
Datalogging 16
4.3
Export Datalog
The command exports the current datalog file in a comma separated value format.
5
Fields and Units
· frame - frame number
· time - frame time (seconds)
· rpm - engine speed
· map - manifold pressure (bar)
· clv - calculated load value (%)
· tps - throttle position (%)
· camangle - cam angle (degrees)
· targetcamangle - cam angle (degrees)
· injector - injector duration (ms)
· ignition - ignition timing (degrees)
· ta - air temperature (degrees centigrade)
· tw - water temperature (degrees centigrade)
· lambda - air/fuel ratio (lambda)
· targetlambda -target air/fuel ratio (lambda)
· shorterm - short term fuel trim (%)
· longterm - long term fuel trim (%)
· knockcount - knock count
· voltage - battery voltage (volts)
· eld - electrical load (amps)
Tuning your vehicle
Basics
First it is important to understand how the Honda ECU determines the appropriate settings for the engine. The Honda ECU uses the speed/density method of calculating these values. The ECU uses the intake manifold pressure and engine speed to index lookup tables for ignition, fuel and cam angle
(amongst other things). Other parameters such as coolant temperature, battery voltage and intake air temperature are used to compensate the table lookup values for the engine. To tune the engine we alter the main tables (fuel, ignition and cam angle) to suit the particular configuration of the engine.
© 2003-2004 Hondata, Inc.
17 Hondata K-Series Programmable ECU
A typical fuel table is shown above. The indices used are rpm (along the bottom) and intake manifold pressure (along the side). The ECU uses interpolation to calculate valves from the table which do not fall exactly on a row or column index. e.g. if an ignition table contains 20 degrees advance at 2000 rpm and 10 degrees advance at 3000 rpm, when the engine rpm is 2500 rpm the ignition advance will be
15 degrees. The interpolation actually occurs in two dimensions (engine speed and engine load) or three dimensions (engine speed, engine load and cam angle).
VTEC
VTEC is one mechanism Honda uses to achieve good emissions, fuel economy and engine power from a small displacement engine. The function of VTEC (variable valve timing and lift electronic control) is to provide two distinct camshaft profiles which are switched electro-hydraulically. The smaller camshaft profile is called the low-speed cam; the larger the high speed cam. The camshaft profiles are switched depending on engine rpm and load, usually from 2500 rpm to 6500 rpm. The main effect on tuning of VTEC is that there are usually two copies of every major table - one for the low speed camshaft, one for the high speed camshaft. Another tuning consideration is the point at which
VTEC switches (see
).
iVTEC
iVTEC ('intelligent' VTEC) is a combination of VTEC and VTC. VTC (variable timing control) is another mechanism used by Honda to increase engine output which decreasing emissions and fuel consumption. VTC controls the intake camshaft advance. Unlike VTEC VTC is not a simple on/off control, rather the ECU controls the intake camshaft advance over a range of 60 crank degrees in steps of 1/4 of a degree. The effect on tuning of VTC is that there are 6 copies of each major table - for cam advance 0, 10, 20, 30, 40 and 50 degrees. In effect this makes the major tables three dimensional.
The Tuning Process
Because of VTC, tuning the K-Series engine is a little different from tuning any other engine. The best
© 2003-2004 Hondata, Inc.
Tuning your vehicle 18
process is:
· Tune the fuel then ignition for every cam angle for the low speed cam (see
and
).
· Tune the fuel then ignition for every cam angle for the high speed cam.
·
Tune the cam angle tables (see Tuning cam angle tables
).
·
Set the VTEC point (see Tuning the VTEC point
).
5.1
Tuning cam angle tables
Introduction
The cam angle is the intake cam advance measured in crank degrees. The allowable cam angle range is from 0 to 50 degrees.
The intake cam is positioned by an electro-hydraulic mechanism, which uses feedback from the intake cam position to alter the position of a solenoid which in turn rotates the intake cam inside the cam sprocket. Because of the design of the mechanism there is a delay between setting the cam position in the ECU, and the cam physically rotating to this position. This delay is around 0.1 seconds per 10 degrees of rotation.
Warning:
With Honda cams there is a physical stop limiting cam advance to prevent valve to valve contact and valve to piston contact. With after market cams it is up to the manufacturer to ensure that the cam lobes are positioned so that valve to valve and valve to piston contact is not possible. Because the cam control mechanism uses a closed-loop feedback system, limiting the cam position in the ECU will not guarantee that the cam position will not exceed what is set in the ECU. Because of this all cams must
have a physical stop to prevent valve contact.
Tuning Guidelines
In short, the better the breathing of the engine; intake, cams and exhaust, the greater the cam advance needed. There is no situation in which best overall performance is achieved by fixing the cam angle to just one setting or using manual cam adjustment wheels for the intake cam. There may be benefits to fitting and adjusting the exhaust camshaft angle, which is not under computer control.
·
With a naturally aspirated engine the cam advance should be set to maximum just after VTEC engagement until about 6500-7000 rpm. From 7000 rpm (where the cam advance should be near 50 degrees) to redline the cam is retarded back around 25 degrees. This procedure is correct for all commercially available after market cams at the date of release of this software, but camshafts which are substantially different from a Honda camshaft may require different settings.
· With a supercharged engine the cam advance needs to be set to maximum (50 degrees or more) throughout the rev range, with only a 10 degrees or so retard above 7000 rpm.
·
With a turbocharger engine the cam advance needs to be less than stock. This is because a turbocharger generates much more exhaust back pressure than a naturally aspirated or supercharged configuration. The higher the back pressure the more cam retard is needed. With small turbos and stock catalytic converters you may need to retard the cam fully to 0 degrees at
8000 rpm
Procedure
· Set the VTEC point high (6500 or 7000) rpm. Only dyno the low speed cam.
·
Set both the high speed and low speed cam angles to zero. Tune the fuel and ignition tables for this cam angle (this is necessary because the engines runs at 0 cam advance when cold and for the first
10 seconds of operation).
·
Set both cam angle tables to 10 degrees, then 20 degrees and so on up to 50 degrees, and tune the ignition and fuel tables for this cam angle.
·
Perform dyno runs at 0, 10, 20, 30, 40 and 50 degrees. This will give you with 6 dyno curves with different cam angles. Set the cam angles in the cam angle map to those which give you maximum
© 2003-2004 Hondata, Inc.
19 Hondata K-Series Programmable ECU
power then re-dyno. The power curve you get should be a maximum of all the 6 individual dyno runs you have just done.
· Now we need to "bracket" the composite cam angle map we have just created. Add 5 degrees to the cam angle map and re-dyno. Subtract 5 degrees and re-dyno. This will verify you have an optimum cam angle map. You will probably find a few RPM points, particularly where the cam is changing angle, that need a little modification to make more power. If you wish you can then bracket the resultant power curve by dynoing with plus or minus 2 degrees cam angle change. The power change at this degree of cam angle change is likely to be about 1 – 1.5 hp on a naturally aspirated engine.
·
Now set the VTEC point low (3000 rpm) and repeat the above procedure for the high speed cam.
Cam Angle at VTEC
If the cam position tables require the camshaft to rotate a large amount at VTEC (e.g. from 20 degrees on the low speed cam angle table to 45 degrees on the high speed cam angle table) you may lose power for 500-700 rpm after VTEC activates, as the cam rotates into the correct position. The best method is to start advancing the intake cam in the low speed cam angle table before the VTEC point, so the cam has to rotate less once VTEC activates. This usually means sacrificing a few hp just before
VTEC point to gain hp after the cams switch. When this is done right the characteristic VTEC change in sound is greatly reduced.
Part Throttle Cam Angle
This applies to the portions of the cam angle table below full naturally aspirates load (column 7 and less).
· At idle and low rpm (below 100 rpm) set the cam angle to 0 or 5 degrees.
· At cruising rpm and load (columns 2 - 7 and 1500 - 4500 rpm) set the cam angle to around 30 degrees. The EGR effect of the extra camshaft overlap will reduce emissions and improve fuel economy at cruise.
·
Above normal cruise rpm set the cam angle to the same value as under full load. This will smooth out gearshifts as the cam shaft will not start to rotate back to zero during the gearshift.
Hints
·
Remember that the cam cannot rotate instantaneously. It takes about 0.1 seconds to rotate 10 degrees. Cam angle changes should not be great over a small rpm interval.
· The intake cam is locked at 0 degrees for 10 seconds after a hot start. Let the engine run for at least
10 seconds after starting the engine before performing a dyno run.
5.2
Tuning fuel tables
Warning:
A lean air/fuel condition will damage the engine. Make sure that you monitor the air/fuel ratio at all times, and abort any dyno run if the air/fuel ratio becomes too lean.
Tuning Fuel at full load
It it necessary to use and lambda meter (air/fuel gauge) to tune to fuel tables. Certain K-Series engines utilise and wide-band oxygen sensor which is useful for tuning, otherwise most dynos are equipped with a lambda meter. It is best to tune so that the air/fuel plot are fairly flat.
Tuning Fuel at part throttle
To tune the fuel for part throttle the aim is to get the air/fuel ratio so that the engine will run correctly in closed loop. Normally the closed loop air/fuel ratio will center around the stoichiometric air/fuel ratio of
14.7:1, so it is best to tune the fuel tables up to column 7 to 14.7:1.
© 2003-2004 Hondata, Inc.
Tuning your vehicle 20
5.3
Tuning ignition tables
Warning
:
Excessive ignition advance will damage the engine. The combustion pressure and load on the engine
(especially bearing stress) increase dramatically if the engine is over-advanced. Do not believe the fallacy that 'more is better' for ignition advance. Too little ignition advance can also damage the engine by increasing the exhaust gas temperature, especially with turbo-charged engines. Do not rely on the
knock sensor to retard the ignition timing if the engine detonates.
The Knock Sensor
One important tool in tuning ignition advance is the knock sensor. This is a sensitive microphone located on the engine block which the ECU uses to determine when the engine is knocking (or pinging). A useful datalog variable is the knock count, which in incremented every time the ECU hears knock. The knock count is reset every time the engine is started. When performing dyno runs monitor the knock count after every run (and preferably during the run). It is normally for the ECU to sense a small amount of knock at the VTEC point, usually 2 times. If the knock count is more than this then it is very likely that the engine is knocking, which should be fixed as soon as possible.
Tuning Ignition Advance at full load
The best way to determine the correct ignition advance at full load is by using a dyno. Generally for naturally aspirated engines it is safe to set the advance near to maximum power, with the aim being to run the least amount of timing possible. A good procedure is to tune for maximum power then retard the timing until you just start to lose power (around 1 hp). At all times monitor engine knock to make sure there is no detonation (even for a naturally aspirated engine). If pinging it audible or the ECU shows that the engine is knocking (e.g. the knock count is increasing) then it is advisable to abort the dyno run, retard timing/add fuel, and restart the run.
With forced induction engines it is important not to over-advance the ignition, otherwise the engine will be damaged in only a few seconds. Use conservative ignition settings, monitor the knock sensor and abort any dyno run if the engine shows signs of knock, pinging or detonation.
Tuning Ignition Advance at part throttle
Tuning ignition advance at part throttle is more difficult than full throttle because it is difficult to accurately determine the correct settings. In general the default calibrations are suitable for part throttle, otherwise an EGT gauge can be used to determine the best ignition advance.
5.4
Tuning the VTEC point
Warning:
·
Do not set the VTEC point too low as the engine will lose oil pressure and possibly damage the engine. It is not recommended to set the VTEC point below 2000 rpm.
· Do not set the VTEC point too high as the high speed cam rocker arm may float on the lost motion assembly, damaging the valve spring retainers. It is not recommended to set the VTEC point over
6500 rpm.
The determine the best VTEC point perform two dyno runs, one with VTEC set low (e.g. 3000 rpm) and the other run with VTEC set high (e.g. 6500 rpm). Set the VTEC point to the intersection of the high speed cam and the low speed cam. Generally if there is a sudden increase in engine output immediately after the cams switch then lower VTEC. Conversely if there is a sudden dip in engine output then raise the VTEC point. Since the VTEC point will be at the intersection of the low speed and high speed cam torque curves, it is normal for the torque to dip around the VTEC point.
© 2003-2004 Hondata, Inc.

Public link updated
The public link to your chat has been updated.
Advertisement
Key features
- Plug-in replacement for factory ECU
- High-speed USB interface
- Editable fuel, ignition, and cam angle tables
- Fuel trim, including individual cylinders
- Expanded tables for forced induction
- Alternate MAP sensor support
- Rev limiter control