How to Clean the Idle Control Valve on a 4Runner

by Leonardo R. Grabkowski

The idle air control valve (usually called an IAC valve) helps maintain the proper idle speed on your vehicle. The Toyota 4Runner idle air control valve is mounted on the throttle body, as it is in all vehicles. Sometimes, carbon buildup near your idle air control valve can cause idling problems. If this is the case, you can try cleaning the valve openings to see if it fixes the problem. In other cases, the valve must be replaced. Most mechanics and service manuals do not recommend cleaning the idle air control valve itself, but rather its mating valves.

Step 1

Open the hood and unhook the negative (-) battery cable. Loosen the nut from the cable and carefully pull it away from the terminal.

Step 2

Trace the air intake hose from the air box to the throttle body. Remove the screws from the clamp attaching the hose to the throttle body and move it out of the way.

Step 3

Unhook the electrical connection attached to the idle air control valve. Pull off the three hoses to detach them from the valve.

Step 4

Remove the four mounting screws on top of the idle air control valve. Pull the valve off and remove the old gasket. Set the valve in a safe place.

Step 5

Spray carbon cleaner (safe for electrical components and catalytic converters) into the two valves. Let the solvent soak for 10 to 15 minutes.

Step 6

Clean the valves thoroughly, on the outside and inside. Use a few shop rags to wipe down the inside part of the valves. Remove as much of the carbon buildup as you can. Let dry for about 30 minutes.

Step 7

Remount the idle air control valve with a new gasket. Do not reuse the old gasket. Tighten the screws, replace the electrical connection and replace the hoses.

Step 8

Reconnect the negative battery cable and start the engine. Let it run for 10 to 15 minutes. The computer needs to "relearn" the idle speed. If your idle speed is still inconsistent, replace the idle air control valve.

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