Ford F150: How to Clean/Replace IAC Valve

Driveability issues are often some of the most difficult problems to diagnose, but an erratic idle or frequent stalling on the F-150 is often a faulty idle air control valve. A quick cleaning or replacement of the IAC valve can typically solve this problem at an inexpensive price.

By Joseph Coelho - May 20, 2016

This article applies to the Ford F-150 (1997-2003).

The idle air control (IAC) valve is used in many electronic fuel-injected engines to maintain proper engine idle. This electronically controlled valve works to vary the amount of air entering the engine while the throttle body is closed to stabilize the idle. Over time and mileage, it is common for carbon buildup to collect in the IAC valve and cause erratic operation. Similarly, the electronics that operate the valve can go bad, thus causing the valve to stick opened or closed. Symptoms of a faulty or malfunctioning IAC valve include hard starting, rough or erratic idle, engine stalling, and engine stumbling during take-off. Fortunately, the IAC valve on most Ford F-150 models are easily accessed and can be cleaned or replaced entirely in a matter of minutes. This article will outline the removal, cleaning, and replacement of the idle air control valve on 1997 to 2003 Ford F-150 models.

Ford F150: How to Clean/Replace IAC Valve

Materials Needed

  • Metric wrench and socket set
  • 1/4" or 3/8" drive ratchet
  • Carburetor cleaner
  • Gasket scraper or razor blade
  • Toothbrush or similar

Step 1 – Remove throttle body cover

Whenever working on your car or truck, especially with electrical components, it is typically a good idea to disconnect the battery.

  • Disconnect the battery cable from the negative (black) battery terminal. Route the cable away from the terminal to prevent accidental contact while working.
  • Remove the throttle body cover, which is typically held in place by three small bolts, if your truck has one.
  • Disconnect negative battery cable
    Figure 1. Disconnect negative battery cable.
  • Remove throttle body cover for IAC valve access
    Figure 2. Remove throttle body cover for IAC valve access.

Step 2 – Remove IAC valve

  • Locate the IAC valve attached on or near the throttle body.
  • Disconnect the electrical plug from the IAC valve. (On the 5.4L Triton engines, it is easier to remove the valve itself before disconnecting the electrical plug.)
  • Remove the (2) 8mm bolts securing the IAC valve in place. Be sure to collect the washers and gasket during removal.
  • IAC valve location on 5.4L engine
    Figure 3. IAC valve location on 5.4L engine.
  • IAC valve location on 4.6L engine
    Figure 4. IAC valve location on 4.6L engine.
  • IAC valve electrical harness plug
    Figure 5. 4.6 liter motor IAC valve electrical harness plug.
  • Bolts securing IAC valve to throttle body
    Figure 6. Bolts securing IAC valve to throttle body.

Step 3 – Clean IAC valve

In some cases, the IAC valve can be cleaned with carburetor cleaner to remove carbon buildup and restore functionality. With the valve removed from the engine, soak the inside or the valve with carb cleaner until it is free of gunk and buildup. A small toothbrush or similar tool can be used to scrub away any stubborn grit. Allow the valve to dry before reinstalling.

  • Spray carburetor cleaner into the IAC valve to rinse away any buildup
    Figure 7. Spray carburetor cleaner into the IAC valve to rinse away any buildup.
  • Dirty valve (left) vs clean valve (right)
    Figure 8. Dirty valve (left) vs clean valve (right).

Pro Tip

Voltage can be applied to the solenoid/motor of the IAC valve to check its functionality.

Step 4 – Reinstall IAC valve

  • Whether installing the old valve or swapping in a new unit, clean the throttle body mating surface of all old gasket material.
  • Position the valve in place with a new gasket and install the 8mm bolts as well as washers. Torque the bolts to approximately 7.5 ft/lbs.
  • Reconnect the electrical harness to the IAC valve.
  • Reconnect the negative battery cable and install throttle body cover (if applicable).

Pro Tip

It is highly recommended that the IAC valve gasket be replaced, as an old gasket that does not properly seal will allow un-metered air into the engine and affect the idle.

Featured Video: IAC Valve Replacement

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