Twin Tec TCFI IID Fuel Injection System Tuning manual

Below you will find brief information for Fuel Injection System TCFI IID. This manual will guide you through the initial setup, tuning, and adjustments required for a proper and efficient operation of the system. The Fuel Injection System TCFI IID, designed for use with 95 CID and larger high-performance racing engines, ensures optimal fuel delivery and engine performance.

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Fuel Injection System TCFI IID Tuning Manual | Manualzz

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Key features

  • Replaces OE Delphi® controller
  • Provides closed-loop AFR control
  • Supports WEGO IID or IIID dual channel wide-band exhaust gas oxygen sensor interface
  • Enables tuning with PC Link TCFI software
  • Offers comprehensive diagnostics and data logging capabilities
  • Includes support for various throttle bodies and intake systems
  • Facilitates auto-tuning for optimal performance
  • Provides detailed idle adjustment instructions
  • Integrates with handheld organizer (PDA) for on-the-go monitoring
  • Provides recommended horsepower limits for different injector sizes

Frequently asked questions

The TCFI IID Fuel Injection System replaces the original equipment (OE) 36 pin Delphi® controller found on 2001-2008 Harley-Davidson® motorcycles with fuel injected Twin-Cam series engines. It controls the air/fuel ratio (AFR) and idle RPM using individual control loops, each of which can operate in open loop or closed loop mode depending on the engine conditions. The system utilizes wideband oxygen sensors to monitor AFR and adjust fuel delivery accordingly, while an idle air control (IAC) stepper motor regulates idle RPM.

The recommended horsepower limits for different injector sizes vary depending on whether the motorcycle uses a siamesed or dual runner intake system. For siamesed runner systems, the stock 3.91 gm/sec injectors are recommended for engines up to 80 HP. For dual runner systems, the stock 4.22 gm/sec injectors are recommended for engines up to 135 HP. Larger injector sizes are available for higher horsepower applications, with recommended limits detailed in Table 1 of the manual.

The auto-tuning process involves operating the motorcycle through a wide range of loads and speeds while monitoring progress using the PC Link TCFI software. This involves slowly accelerating through the useable RPM range in every gear, operating the motorcycle at various fixed speeds, and performing wide open throttle runs on a closed course. The goal is to cover as many cells in the BLM tables as possible to achieve optimal fuel delivery and engine performance. The manual provides detailed instructions on the auto-tuning process, including how to examine BLM tables, smooth out Alpha-N and front cylinder trim tables, and save and upload the edited setup data to the TCFI unit.

If you experience spark knock, you can reduce the ignition advance by 3-5 degrees using the PC Link TCFI software. The manual recommends examining engine data in TCFI Log to determine the specific manifold pressure and RPM values that cause spark knock. It also mentions that large displacement engines are prone to spark knock at relatively low MAP values during throttle roll-on, so you may need to reduce ignition advance throughout the entire MAP range.

Aftermarket throttle bodies may require adjustments to ensure proper operation with the TCFI system. You need to ensure that the throttle system operates smoothly, the take-up cable has some slack, and the return cable forces the throttle blade(s) against the idle stop. The manual provides detailed instructions on idle TPS check and adjustment, which are crucial for proper throttle position sensing and accurate fuel delivery.

If the engine fails to start, several factors could be causing the issue. First, verify proper installation and setup of the TCFI unit, ensure the battery is fully charged, and ensure the IAC system is initialized by cycling the run/stop switch. Check for flooding caused by excessive priming and clear it by disconnecting the fuel pump relay and cranking the engine. The manual also provides additional troubleshooting tips for starting problems, such as checking the idle stop setting, adjusting priming and cranking fuel values, and verifying the functionality of the stock ECM.

If the engine stalls, it's likely caused by insufficient fuel or excessively lean AFR. You can monitor AFR values using TCFI Log or TCFI View software to identify the root cause. Based on the observed AFR values, adjustments to the idle cells in the Alpha-N table may be necessary. If the AFR is lean, you can try adding 10-20% fuel to those cells. The manual also offers additional troubleshooting tips for stalling problems, such as checking the cold start enrichment tables and ensuring proper ignition advance settings.
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