Not every EFI application is going to use a drive-by-wire throttle body; plenty still use the tried-and-true drive-by-cable unit. If your vehicle uses a Holley Sniper, Terminator X, or other Holley EFI engine management systems, this video will help you set the idle air control (IAC) value.
To start this process, the first thing you’ll want to do is fire up your vehicle and make sure it gets to its normal operating temperature. Once the vehicle has reached operating temperature, you’ll want to confirm the idle speed is correct by making sure it matches what you set it to when you went through the setup process for the EFI system.
With everything confirmed, it’s time to set the IAC value. This value is shown as a percentage where 0% means fully closed and 100% means fully open. You want the IAC position to register between 2% and 10%, but 3% to 5% is ideal for most applications. This requires the throttle position sensor (TPS) to be at 0%.
If the IAC position is reading 0%, the throttle blade(s) are open too much. This means the IAC passage cannot help control the idle speed. You need to turn the curb idle screw counterclockwise; this will close the blade(s) and increase the IAC value toward the desired range. If the IAC position shows a value greater than 10%, the throttle blade(s) are not open enough. This will require you to turn the curb idle screw clockwise to correct the IAC value.
In this video, Jeremy Soermer goes into more detail about how to set your IAC and how to deal with any TPS issues that might come up from incorrect IAC values.
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