Transforming a classic car’s performance with FiTech Fuel Injection should mean a smoother, more efficient drive. However, when issues start showing up, they can turn the excitement of an upgrade into a series of headaches.
Many users have encountered specific problems that disrupt reliability, leaving them unsure of where to start fixing things.
Here, we’ll discuss the most common FiTech EFI issues, their actual causes, and practical steps to get your system running as it should.
1. Communication Problems Between the ECU and Handheld Controller
A significant concern with FiTech EFI systems is when the handheld controller can’t connect to the ECU, often displaying a “No Response” message.
This loss of communication prevents users from tuning, monitoring, or adjusting settings and can leave the car running poorly or even completely inoperable if the issue is not addressed.
The communication issue often stems from a faulty cable connecting the controller and ECU. The cables with FiTech units are sometimes fragile and can break internally if pinched or bent, leading to intermittent or complete signal loss.
Another common cause could be an unstable power supply to the ECU. For the ECU to communicate properly, it requires a steady 12-volt power source and a good ground connection.
Any drop in voltage due to wiring problems, a weak battery, or poor grounding can disrupt the connection with the controller.
Sometimes, the handheld controller itself may be to blame due to firmware glitches or malfunctions. Some users have found that after attempting firmware updates, the controller stopped communicating, particularly if the update wasn’t completed as specified in FiTech’s guidelines.
To address this issue, first, check the communication cable for signs of wear or damage and replace it with a shielded cable if necessary.
Ensure the ECU has a steady, grounded power supply and the power connections are clean and secure. If the handheld controller is at fault, try re-flashing or updating the firmware carefully according to FiTech’s instructions.
If none of these steps work, contacting FiTech’s customer support may be necessary, especially if the issue occurred after a firmware update.
2. Fuel Pump Failures and Performance Issues
Fuel pump problems are another common concern among FiTech EFI users. Symptoms of fuel pump failure include erratic engine performance, difficulty starting, stalling, and fluctuating or reduced fuel pressure readings. These issues can make the vehicle unreliable and potentially damage the engine by causing it to run lean.
One major reason for fuel pump failure is overheating, particularly in in-tank pumps. This is especially true for the FiTech Fuel Command Center (Part #40003), which many users install in engine bays.
The Command Center design has sometimes been criticized for its inability to effectively dissipate heat, which can lead to vapor lock and pump burnout.
Another common factor is fuel contamination. Dirt, rust, or debris in the fuel tank can enter the pump, damaging internal components and causing failure. This is especially an issue for older vehicles where fuel tanks have not been adequately cleaned or replaced.
Incorrect installation practices can also cause fuel pump issues. If the pump is not mounted correctly or lacks adequate wiring, it may fail prematurely. Also, not using pre-filters can allow contaminants to enter the pump, causing further wear and reducing lifespan.
To address these issues, consider relocating the Fuel Command Center away from heat sources or replacing it with an in-tank pump designed for EFI applications.
Installing quality fuel filters can prevent contamination from damaging the pump. Additionally, upgrading to a more robust pump designed to work with FiTech systems and ensuring proper installation according to guidelines can improve performance and reliability.
3. Electrical Interference Affecting EFI Performance
Electrical interference, also known as electromagnetic interference (EMI), can lead to issues with FiTech EFI systems.
Symptoms of EMI include erratic sensor readings, ECU resets, engine misfires, and fluctuating data on the handheld controller. These issues can make tuning difficult and may impact overall engine performance.
High-energy ignition systems, such as aftermarket ignition boxes, can generate EMI interfering with the ECU’s operation.
Poor wiring practices, such as running EFI wiring alongside ignition wires, can increase the risk of interference. Insufficient shielding on signal wires also leaves them susceptible to electrical noise. Inadequate grounding practices can also contribute to electrical interference.
If EFI components are grounded at multiple points or share grounding locations with high-current devices, ground loops may form, introducing noise and disrupting ECU data processing.
Route EFI wiring away from ignition components and high-voltage wires to combat electrical interference. Using twisted pairs for signal wires can reduce susceptibility to EMI.
Ground all EFI components at a single point on the engine block to avoid ground loops. Adding ferrite beads to power and signal lines and shielding sensitive wires with grounded metal foil can provide extra protection.
4. Oxygen Sensor Failures and Incorrect Fuel Mixtures
A properly working oxygen sensor is essential for accurate fuel adjustments, allowing the EFI system to keep the engine running efficiently. Sensor failures, however, can lead to poor performance, excessive fuel consumption, and difficulty tuning.
Improper sensor installation is a common reason for failure. The O2 sensor should be positioned 6–8 inches after the exhaust collector or merge point and mounted between the 10 and 2 o’clock positions to prevent moisture accumulation that can damage the sensor when it heats up.
Also, exhaust leaks near the sensor can introduce outside air, skewing readings and mistakenly causing the ECU to think the engine is running lean.
To address oxygen sensor issues, ensure the sensor is installed correctly and check for exhaust leaks. Regularly inspect the sensor for contamination from oil or leaded fuels, as these substances can damage the sensor quickly. Following these guidelines can help extend sensor life and ensure accurate readings.
5. Idle Control Problems and Drivability
FiTech users frequently report idle control issues, which include rough idling, surging, or stalling. A common indication of idle control issues is when the Idle Air Control (IAC) valve’s steps fall outside the recommended range.
Vacuum leaks are often a primary cause of idle control issues, as unmetered air can disrupt the air-fuel mixture, making it difficult for the ECU to maintain a stable idle. Common sources include poorly sealed intake manifolds, cracked hoses, or leaks around the throttle body gasket.
Improper IAC settings can also lead to idle issues. IAC steps should generally fall within 3–10 steps for optimal operation, as FiTech recommends. Over-adjusting the throttle stop screw can also interfere with IAC operation, leading to unstable idle.
First, check for vacuum leaks and seal any found to address idle control issues. Properly calibrate the IAC according to FiTech guidelines, adjusting the throttle stop screw as needed. Also, ensure the throttle body components are in good condition and functioning correctly.
6. Temperature Sensor Failures Affecting Engine Performance
The coolant and air temperature sensors are essential for EFI systems to calculate accurate fuel delivery. When these sensors fail, the engine may run too rich or lean, affecting performance, especially during warm-up or under varying load conditions.
Faulty or damaged sensors, wiring issues, and incompatible sensor types contribute to temperature sensor issues. Long-term exposure to engine heat and vibrations can degrade wiring, leading to intermittent or false readings.
Replacing faulty sensors with FiTech-approved components, inspecting connections, and ensuring wiring is in good shape can help maintain sensor accuracy.
Using diagnostic tools to check sensor readings against actual temperatures will ensure the ECU receives reliable data for fuel control.
7. Firmware and Software Issues Affecting System Operation
Software glitches or outdated firmware can lead to system freezes or error messages on the controller, affecting tuning and engine performance.
Firmware updates can sometimes introduce issues if not performed correctly or if incompatible versions are used between the ECU and controller.
To prevent software problems, follow FiTech’s update procedures carefully and ensure the ECU and controller have compatible firmware.
Backing up all settings before updating safeguards against data loss. If problems arise during updating, contacting FiTech support rather than retrying repeatedly can prevent further issues.
8. Overheating of EFI Units Due to Installation Issues
EFI units can overheat in cramped, hot engine bays, especially in turbocharged applications or near exhaust manifolds. Overheating can cause the unit to shut down or operate erratically, potentially damaging internal components.
To prevent overheating, relocate the EFI unit away from heat sources and ensure adequate airflow. Adding heat shields or thermal barriers between the EFI unit and hot components can reduce heat transfer. Periodic inspections for electrical issues or malfunctions that may cause overheating are also advisable.
9. Self-Learning Limitations with Specialized Engine Setups
While FiTech’s self-learning capability allows the EFI system to adapt to most conditions, engines with unique setups—like aggressive camshafts that produce low vacuum—can confuse the system. In these cases, the ECU may fail to adjust fueling accurately.
If self-learning falls short, manual tuning may be necessary. Access advanced settings to fine-tune fuel maps, idle control, and air-fuel ratios to match the engine’s characteristics. Experienced tuners familiar with FiTech setups can provide additional guidance.
10. Voltage Instability Impacting EFI System Stability
FiTech EFI systems require a steady voltage, typically above 12.5 volts, to operate reliably. Voltage fluctuations can cause the system to reset or behave erratically, especially when additional electrical loads, such as headlights, are in use.
Upgrading the alternator, replacing a weak battery, and improving wiring connections can maintain voltage stability. Running a dedicated EFI power line directly to the battery with proper fusing will further reduce interference from other electrical loads.
Final Thoughts
FiTech EFI systems bring modern fuel injection advantages to classic cars but may have specific challenges. Recognizing these common issues, from communication problems to self-learning limitations, helps you troubleshoot more effectively.
Seeking support from FiTech or advice from online communities can be invaluable when dealing with complex issues. With a careful approach and attention to detail, FiTech EFI users can maximize system performance and enjoy a seamless EFI experience.
Was This Article Helpful?
i had my ls ultimate system around 4 years. When i finally got it working i lived with it. It will not start when hot i shoot starting fluid it breather crank right up. I have grown tired of this. changed FI tuning prime fuel from 198 to -70 and crank fuel at 170 deg from 70to-70 iac from 24 to-7o in steps. pro tuning 195 deg 26.6 starts cold every where hot not a all use ether starts right up’ other problem will not down shift when you floor it lossy to drive any advise will help if there is a tuner near the outer banks of NC i will gladly go
Hi Timothy,
Sounds like you’ve really been through it with your FiTech setup—four years of tweaking and it still won’t hot start properly? That’s frustrating, especially when cold starts are fine but you’re stuck using starting fluid when it’s warm. You’ve made a ton of detailed adjustments, so clearly you’ve put in the time.
The hot start issue is something a lot of FiTech users run into. Sometimes it’s related to heat soak—if the ECU or fuel lines are getting too hot, that can cause vapor lock or mess with sensor readings. Voltage drop during cranking can also throw things off, so it’s worth checking that your battery is holding strong during startup (shouldn’t drop below 10 volts).
As for the no downshift when flooring it—that sluggish response can sometimes come down to throttle position sensor (TPS) calibration or shift point settings inside the ECU. You might want to double-check both and see if a small tweak gets the transmission behaving better. Also make sure your transmission fluid level and condition are good, just to rule that out.
If you’re still stuck and want to take it further, you could look into a tuner familiar with FiTech systems. I know you’re near the Outer Banks—while local options might be limited, there are some EFI tuning services online (like Ramtech EFI) that offer remote help and can walk you through adjustments based on your logs.
Really hope you can get it running the way it should. You’ve clearly put in the work—now it just needs to pay off.
I am having the exact same problem as Timothy. I have a unit on a 350 oldsmobile and it will not start hot but fires right up cold. I have changed the battery twice and put a high torque starter on it. It cranks a lot better but not start hot. I gave it a shot of either and it fired right up. I’m going to check the fuel lines but the pressure is where it should be I have two of these systems and the other system my display quit. The one from the oldmobile will work in my chevy truck but the truck unit will not work in the olds. Can I send this in to be repaired? Thanks
Hi Terry,
That sounds like a heat-related EFI failure, don’t risk further damage. Contact FiTech support right away to get it checked or repaired before it causes a bigger problem.