10 Common Mistakes to Avoid When Doing EFI Tuning

Electronic Fuel Injection (EFI) systems are becoming increasingly popular in the automotive industry, and for good reason. They offer improved performance, better fuel economy, and lower emissions. However, EFI tuning can be tricky and there are some common mistakes that can be made. In this article, we'll discuss 10 of the most common mistakes to avoid when doing EFI tuning.

The first mistake is not understanding the difference between dry and wet flow. Dry flow refers to the amount of air that passes through the intake manifold without any fuel being added. Wet flow, on the other hand, is when fuel is added to the air before it enters the intake manifold. It's important to understand the distinction between these two flows in order to properly tune an EFI system.

The second mistake is using leaded fuel and oxygen sensors. Lead is a toxic substance that can damage an engine's components over time. It's essential to use unleaded fuel and oxygen sensors when tuning an EFI system. The third mistake is adjusting with a detonation sensor.

Detonation sensors measure the pressure inside the combustion chamber and can be used to adjust the timing of an engine. However, they should not be used as a substitute for a wideband oxygen sensor, which is more accurate and reliable. The fourth mistake is underestimating the power potential of a carburetor. Carburetors are still a great air-fuel mixing device and can produce impressive power levels.

Nevertheless, they should not be used as a substitute for an EFI system in modern engines. The fifth mistake is not taking into account the effects of heat on an EFI system. Fuel-injected engines are more affected by higher ambient temperatures and the heat of the lower part of the bonnet than carbureted engines. Therefore, it's important to use an intake manifold made of thermoplastics such as DuPont Zytel, which is relatively impermeable to heat. The sixth mistake is using an open-element air filter on a 5.0L Mustang engine.

This can cause idle instability due to turbulence created by the activation of the clutch fan. To avoid this problem, it's important to use a sheet metal cover to isolate the air filter from this turbulent air. The seventh mistake is not using a ram-air kit for better breathing. Ram-air kits provide cold air from outside the engine compartment, which can improve performance significantly. The eighth mistake is not setting up a closed-circuit timing system correctly. When using a closed-circuit timing system (detonation delay), substantially more spark extraction is needed to turn off detonation than would be needed so that abnormal combustion would never start. The ninth mistake is not re-running the initial calibration process after making adjustments.

This will ensure that all settings are correct and that the engine will perform as expected. Finally, the tenth mistake is not testing after making adjustments. It's important to drive the car for a couple of days after making adjustments and restarting the engine several times during this period.


EFI tuning can be tricky but with some knowledge and experience it can be done successfully. By avoiding these 10 common mistakes, you'll be able to get your EFI system running optimally in no time.

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