FiTech Upgrade and Tech Tips

By Ron Ceridono – Photography By The Author

Although the hobby we all know and love is steeped in tradition, hot rodding has always embraced technology. Early examples include aluminum heads for Flathead Fords; today, they feature electronic fuel injections like those offered by FiTech.

02 Side by side comparison of matte gold and polished aluminum FiTech EFI throttle bodies — Over the year, FiTech has made subtle changes to the throttle body design; the latest version is on the right.

We cannot often conduct long-term testing on hot rod components, but we’ve accumulated nearly 50,000 trouble-free miles using a FiTech throttle body system. So, when it was time to select an induction system for a new project, we again chose the same system we used: a Go EFI 4 600hp system. Although this system is rated for up to 600 hp, it is appropriate for engines producing 200 hp and above.

03 Close up of FiTech throttle linkage and wiring harness on gold anodized EFI unit — One of the changes made is the location of the secondary throttle stop; in the early design, it was located on the right rear side of the throttle body.

As often happens, FiTech has refined its products over the years, so we decided to examine the similarities and differences in these systems. From a functional standpoint, FiTech got it right from the beginning; the new systems are still self-tuning, and installation remains simple. After basic engine information is entered into the handheld controller, it establishes parameters for air/fuel ratios at idle, cruise, and wide-open throttle. In simple terms, the self-learning function involves the electronic control unit (ECU) using feedback from various sensors to adjust and maintain the air/fuel mixture under all conditions.

04 Rear view of polished FiTech Go EFI 4 showing dual fuel inlet ports and throttle linkage — On the late-style throttle body, the secondary throttle stop is positioned on the left rear side, making it easier to access.

Those sensors are:

-Mass Air Flow (MAF) sensors measure the volume and density of air entering the engine
-Manifold Absolute Pressure (MAP) for altitude compensation and load correction
-Coolant Sensor (CTS) monitors operating temperature for fuel adjustments (think of it as the choke)
-Throttle Position Sensor (TPS) feedback for fuel control
-Idle Air Control (IAC) bypasses air to maintain a consistent idle speed
-Inlet Air Temp (IAT) compensates for changes in air density due to air temperature
-The Oxygen Sensor monitors the amount of oxygen in the exhaust to indicate how rich or lean the fuel mixture is
-Besides the oxygen sensor and CTS, all other sensors are housed in the throttle body

05 Mounting base comparison of gold and aluminum FiTech throttle bodies with bolt hole spacing — Here, the difference in thickness of the mounting flanges can be seen; the new version on the right is slightly thicker.

Although there are minor differences in the throttle bodies (as noted in the captions), the installation procedure remains the same as the engine requirements. The engine must be in good condition; EFI won’t cure mechanical shortcomings. The exhaust system must be free from leaks, as these will disrupt the oxygen sensor’s readings, leading to improper air/fuel ratios. Likewise, intake manifold leaks create similar problems. The charging system must be capable of maintaining the correct battery voltage and the system must be properly grounded. Another consideration is the ignition system. Point-controlled systems and Mopar electronic ignitions with the typical rectangular controller and dual-element ballast resistor will not provide the correct tach signal to the FiTech ECU. However, FiTech now offers a line of replacement distributors that solve both problems.

06 Top view of polished EFI throttle body revealing four venturis with smooth bore finish — To accommodate larger displacement engines, the size of the idle bypass opening has been increased.

Due to FiTech’s refinements over the years, there are four versions of ECUs and handheld devices. However, rather than making previous systems obsolete, FiTech offers updated software that can be easily installed in the handheld controller via a home computer.

07 Top view of gold FiTech throttle body showing injectors inside venturis for atomization — In comparison, this is the idle bypass in earlier throttle bodies (arrow). On large displacement engines, the smaller bypass required the throttle valves to be opened further at idle.

To make software system updates, the version of the system must be identified. This is done through the configuration of the handheld display. The older, smaller handhelds may have nothing around the joystick, while the later, larger handhelds may have four triangles on the right edge or may feature a plain surface with two dots. Once the handheld is identified, FiTech can supply the appropriate software updates, which is critical. Loading the wrong software into the handheld can permanently damage it, void the warranty, and require the purchase of a replacement.

08 FiTech control module with Deutsch connectors for integration into EFI system wiring — FiTech throttle body EFI systems now include a remote-mounted relay and fuse block.

Once the handheld is identified, a FiTech representative will provide the appropriate updated software file. After downloading the update to a desktop computer, the handheld is connected to the computer. Following the instructions on the computer screen, the original software is removed from the handheld, and the new version can be installed. Once the handheld is reinstalled, the ECU in the throttle body will operate on the new system. (FiTech has a complete video showing the update process.)

09 Open FiTech fuse and relay box showing labeled fuses for pump and ignition circuits — In earlier systems, the fuses were in the wiring harness, while the relays were mounted in the throttle body ECU.

In subsequent installments of Modern Rodding, we will present more “fuelish pleasures,” such as the complete bumper-to-bumper procedure for installing a FiTech fuel injection system, along with tips on tuning, maintenance, troubleshooting, and additional information on Mopars.