TCFI4 – Race ECU – HD Twin Cam – 2001-2013 – 36 Pin Delphi

Description

TCFI4 Race ECU – Built for 2001-2013 Harley-Davidson® Twin Cam with 36 Pin Delphi®

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Not legal for sale or use in California or on any pollution controlled vehicles.

Between 2001 and 2013, Harley-Davidson® equipped most Twin Cam models with a 36 pin Delphi® connector and J1850 data bus. While reliable from the factory, this system has well-known limitations when you start building for serious performance. The TCFI4 was designed from the ground up to replace that stock ECU with a fully programmable, race-ready solution that plugs directly into your existing wiring harness.

Unlike competitor products that piggyback onto the stock Delphi® controller and inherit its limitations, the TCFI4 takes complete control of fuel and ignition. The result is a system that can handle anything from a mildly modified street engine to a forced induction race build. This system has been tested on engines up to 145 CID and over 250 HP.

The TCFI4 is also the only ECU in the lineup that supports an EFI to carburetor race conversion — making it the go-to choice for drag racers who want to ditch fuel injection entirely while keeping precise ignition control. If you are building a 2001-2013 36 pin Twin Cam for the track or the street, the TCFI4 is your starting point.

Important compatibility notes:

• Not compatible with 2011-2017 Twin Cam models with CAN data bus — use TCFI5 instead.
• Not compatible with 2008-2013 Twin Cam Touring models with electronic throttle control 73 pin connector — use TCFI6 instead.
• Not compatible with 2014-2016 Twin Cam Touring models with electronic throttle control — use TCFI7 instead.
• All 2002-2017 V-Rods utilize the VRFI4
• All 2017+ M8 engines utilize either M8FI G8 (2017-2020) or M8FI G9 (2021-2024).

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Key Features

The TCFI4 is built for serious performance tuning. As a result, it includes the following features:

• Plug-in replacement for the 36 pin Delphi® controller with J1850 data bus
• Alpha-N (throttle position and RPM based) fuel control — eliminates issues with long duration and high overlap camshafts
• Auto-tune fuel curves for front and rear cylinders on a dyno or on-road via the included WEGO IIID dual channel wide-band oxygen sensor interface
• Includes Bosch LSU 4.2 wide-band sensors for both front and rear cylinders
• Fully programmable ignition advance curves — same proven control as the TC88/TC88A systems
• Fully programmable idle air control, idle RPM, and cold start characteristics
• Extended data logging — Anytime the engine is running, the ECU is saving and storing data.  The built in ECU memory stores 60 minutes of operating data at 10 samples per second.  The information is stored in a continuous loop, after 60 minutes it starts to overwrite the initial stored data.
• Programmable user input for two step RPM limiting, nitrous retard, and shift kill
• Programmable user output for shift light, nitrous activation, and electric shifter
• Full SAE J1850 data bus support for instrument cluster and TSM/TSSM communication
• Speedometer and odometer recalibration via PC Link software
• Billet aluminum housing with black anodized finish
• Easy plug-in installation

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Why Alpha-N Fuel Control?

Most competitor products that interface with the stock Delphi® controller still rely on speed-density fuel control. Unfortunately, long duration and high overlap camshafts cause problems with manifold pressure — particularly at idle and cruise RPM. Speed-density fuel control simply cannot cope with these conditions.

In contrast, the TCFI4 uses Alpha-N fuel control — the same technology used in high-end automotive racing systems. Alpha-N is based on throttle position and RPM, eliminating any dependence on manifold pressure. The result is consistent, reliable fuel control regardless of camshaft specifications.

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Auto-Tuning With the WEGO IIID

The included WEGO IIID dual channel wide-band oxygen sensor interface allows you to auto-tune fuel tables while riding — no dyno time required. Simply program your desired air/fuel ratio targets and the system does the rest. In addition, auto-tuning under real riding conditions typically takes only a few hours and produces more realistic results than dyno tuning alone.

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PC Link Software – Free Download

PC Link software is included at no charge and runs under Microsoft Windows XP, Vista, 7, 8, 10 and 11. It gives you full control over all engine control tables and parameters, including:

• 3D ignition advance tables
• 3D air/fuel ratio tables
• 2D cold start enrichment and idle air control tables
• Programmable user input and output functions
• Speedometer and odometer recalibration

The TCFI4 connects to your PC via a USB adapter and cable that is included with the unit. The USB interface plugs into the “add-on four pin” Daytona Twin Tec diagnostic connector. This connector will either be located on the WEGO IIID unit or it will be added into the the OE 36 pin motorcycle wiring harness. The software will also run in demo mode without a TCFI4 connected.

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Data Logging Software – Also Free

The TCFI Log software gives you comprehensive data logging and diagnostic capability. Specifically, it allows you to:

• Display real time engine data during dyno testing
• Download and review the last 60 minutes of operating data at 10 samples per second
• View elapsed time across 13 RPM bands from idle to 6999 RPM
• Track maximum engine RPM and time spent at the RPM limit
• Review and clear historical diagnostic codes
• Display operating statistics in histogram chart format

Like PC Link, TCFI Log is a free download and runs in demo mode without a TCFI unit connected.

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Emissions Legal Version – TCFI EX

The TCFI EX is 50-state street legal (ARB E.O. No. D-641-5) for 2001-2006 88 CID Twin Cam engines with the 36 pin Delphi® system, excluding 2006 Dyna models with OE oxygen sensors. It is recommended for all street-driven applications.

Compared to the standard race version, the TCFI EX has a few limitations:

• Air/fuel ratio table changes are only permitted above 2750 RPM or 35% throttle
• Some limits apply to the range of spark advance table changes
• Programmable user input and output functions are not available

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Available Models

• 17400 – TCFI4 with Wideband Sensors — Race ECU 2001-2011 Twin Cam with 36 pin Delphi® and J1850 data bus (excludes 2011 Softail/Dyna with Can Bus and 6 pin diagnostic connector [use TCFI5])
• 17401 – TCFI4 Sportster Version with Wideband Sensors — Race ECU 2007-2013 Sportster Twin Cam with 36 pin Delphi®
• 17402 – TCFI4 3 Bar Speed-Density Version — Race ECU 2001-2011 Twin Cam with 36 pin – For high boost turbo or supercharged applications
• 17403 – TCFI4 EFI to Carb Racing Version – Race ECU – 2001-2011 Twin Cam with 36 pin Delphi® and J1850 data bus
• 17406 – TCFI4 TCFI EX Open Loop Version – 2001-2006 88 CID Twin Cam engines EO D-641-5.  Open Loop – No Widebands – Larger aftermarket race engines we recommend our race version with Wideband Sensors
• 17407 – TCFI4 Sportster Open Loop Version – Open Loop – No Widebands – Race ECU 2007-2013 Sportster Twin Cam with 36 pin Delphi®
• 17408 – WEGO ADD ON KIT – Converts Open Loop Version of the TCFI4 to Closed Loop Wideband Control, includes WEGO IIID, Two Wideband Sensor and O2 bungs.

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Downloads & Documentation

• TCFI4 Install Guide – Read First
• TCFI4 Quick Start
• TCFI4 Full Manual
• TCFI Idle Tech Note
• USB Adapter Instructions
• TCFI 300 kPa Tech Note
• TCFI Tech FAQ
• TCFI Software Download Page – PC Link and TCFI Log
• Wideband O2 – Sniffer Tech Note
• EFI to Carb Race Conversion – Tech Note

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 TCFI Installation

 

Wide-Band Oxygen Sensor on Front Pipe

 

Wide-Band Oxygen Sensor on Rear Pipe

 

Sample 3D Ignition Advance Table

 

Sample 3D Air/Fuel Ratio Table

 

Sample 2D Idle Speed Table 

Real Time Engine Data Display

 

Data Logging Chart Display