Want complete control of your Twin-Cam engine management so that you can easily re-tune each time you make a performance upgrade without a visit to a dealer or a dyno shop? Then the Daytona Twin Tec TCFI III Fuel Injection Kit (TCFI III-KIT MSRP $875.00) is an upgrade option you may want to consider, available for ’01-’06 Twin Cams with 36-pin Delphi systems.
This kit is serious business that delivers serious benefits. It consists of two main components. The first is the third generation TCFI III (Twin Cam Fuel Injection) module, which is a fully programmable plug-in replacement for the stock 36 pin Delphi ECM (Engine Control Module). The TCFI solves tuning problems with highly modified engines using the same technology as high-end automotive racing. The TCFI also has built-in data logging that stores the last 60 minutes of operation data at 10 samples/second.
The second component is the new WEGO IIID (Wide-band Exhaust Gas Oxygen) interface, which allows auto-tuning of EFI parameters during actual on-road riding conditions. The kit uses a Bosch LSU 4.2 wide-band sensor for both front and rear cylinders. The user programs a table with the desired air/fuel ratios, and the system does the rest. Unfortunately, it doesn’t auto-tune timing. But, hey, “auto-tuning,” how cool is that? Let’s see.
However, before we do, we must consider a big issue. The first sheet in the instruction package is a bright yellow piece of paper with the warning “Read before opening any boxes.” Presumably that’s to facilitate returning those boxes if the owner gets cold feet after reading the remaining cautions. Foremost of those is, “If you have never worked with H-D EFI systems, the TCFI is not the place to start.” The necessary skills and resources you’ll need are PC literacy, basic engine tuning concepts, mechanical ability, and time. A service manual for your model would be handy, too. The bottom-line caution is that before you continue you need to make a realistic assessment of your skill level and commitment.
Having done that, we plunged ahead with our untrained-but reasonably competent-garage-mechanic/writer installing the kit on his stock ’07 Road King Custom. While the TCFI kit sounds intimidating and complex, it is also well-designed, documented, and straightforward. We took our time and worked through each step in the process. Plus, we tapped into the Daytona tech support and the readily available and enthusiastic help from Harley-Davidson Forum members, notably John Pike (SpikeCT).
Setup began in the office where we installed the two major software components and the USB Interface on a laptop PC. The PC Link TCFI III software is the primary programming and tuning tool because it allows the user to upload custom ignition and fuel tables and other engine parameters to the TCFI III. The TCFI III Log software allows the user to view real-time engine data, download and display stored operation data, and to control certain engine functions. The USB Interface provides communications between the TCFI III module and the PC software.
Installation of the hardware components on our ’07 H-D Road King Custom was not difficult. However, it was tedious because the Motor Company doesn’t expect the owner to replace critical electronic parts, therefore the removal of those parts often included a couple of gotchas, which required moderate shop skills to work around. We noted those as we encountered them.
After everything was installed on the Road King, the TCFI required an initial setup before starting the engine for the first time. This setup establishes the base TCFI parameters such as engine horsepower, injector size, and the appropriate ignition and fuel tables. Daytona Twin Tec provides several setup files for typical engine applications to use as starter sets. For our bike we used the ’07 96CID file. Once the initial setup file was uploaded, the TCFI was ready for idle tuning and performance auto-tuning.
Idle tuning uses the PC software to check the TPS (Throttle Position Sensor) and to verify that basic engine variables are within nominal ranges while the engine idles. Adjustments at this stage are critical to insure that the engine is within sound operational limits before riding and auto-tuning.
Auto-tuning is a closed-loop cyclic process of riding the motorcycle at varying loads and speeds, each time downloading the current setup data from the TCFI, editing and applying the tables for improved operation, uploading the data back to the TCFI, then repeating. Typically five runs are sufficient for tuning.
Here we’ve covered the basic installation of the TCFI III kit and tuning for a stock motorcycle. During our first couple of auto-tune runs we did encounter some hesitation and pinging. However, after the final run, the stock Road King performed as well as or better than before. We didn’t spend much time tweaking the TCFI III for the stock configuration because we’ll soon upgrade the air and exhaust. We’d rather devote our time to maxing out those.
**Daytona Twin Tec LLC