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IAC Valve Replacement

How to Replace the IAC Valve on a Ford F-150

 

The IAC valve, short for idle air control, is an electronically controlled valve that allows air to bypass the throttle body. During idle, the IAC opens and closes as necessary to provide the engine with the correct amount of air it needs to run at idle. In time, the IAC tends to suffer from carbon buildup, which causes it to respond slowly and/or improperly. Additionally, the electric motor that actuates the IAC valve can wear out and cease to function. In either case, the signs of a bad IAC valve are engine stalling, stumbling, a rough idle and/or poor idle quality (often times most present on start up). Fortunately, replacing the IAC should only take 15 to 30 minutes with basic hand tools.

 

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• The IAC valve is located on the driver side rear portion of the throttle body. Remove the plastic guard that covers the throttle body by removing the three 10mm bolts.

• Locate the valve and remove the IAC valve wiring harness (see photo).

• Remove the two 8mm bolts that hold the IAC valve in place, then gently lift the IAC from its mounting plate. Also remove the old gasket without dropping any loose debris or gasket material into the holes on the IAC valve mount.

• If necessary, carefully clean the surface of any gasket material that may have stuck to the mounting flange. A shop vac can be used to prevent small pieces of gasket material from falling into the tubes of the mounting flange.

• Once the mounting surface is clean, install the new gasket and new IAC valve (reverse removal).
Optional - Place a small amount of anti-sieze on the tip of the 8mm mounting bolts. The bolts are coated, so corrosion isn't a huge concern. However, the anti-sieze will act as a lubricant and prevent the hard steel bolts from cross threading into the soft aluminum flange.
• Tighten the 2 bolts that hold down the IAC, being carefully not to overtighten as the aluminum threads can become damaged easily. Reconnect the wiring harness and reinstall the plastic cover to complete the IAC valve replacement.

• Comparison of the new and old IAC valves. In some instances, buildup in the valve causes it to malfunction or respond slowly, while in other instances the actuator itself stops working. If the motor still works, clean the valve and keep it as a spare.