Test an Idle Air Control Sensor
The idle air control valve, also simply known as the IAC valve, acts just like an idle air screw used to work on older vehicles. However, unlike the adjuster screw, the IAC is constantly making small adjustments to the vehicle's idle to keep it within the manufacturer's specified RPM range. Over time, the IAC valve can become clogged, or its motor can simply stop working. This failure causes the vehicle's idle to become unstable at times. You can test the idle air control valve in about an hour, with an assistant's help.
Instructions
1. Open the vehicle's hood. Trace the air intake tube towards the engine until you reach the throttle body. The throttle body is the metal component that connects the intake tube to the engine.
2. Use a Phillips-head screwdriver to remove the idle air control valve. The idle air control valve is the small electrical component attached to the throttle body.
3. Instruct your assistant to turn the key to the "On" position, but not to start the vehicle. Observe the plunger at the end of the IAC valve; see if it moves in or out when the key is turned to the "On" position. The movement of this plunger means the IAC valve is working properly; lack of movement means the valve is either stuck or the IAC valve's electric motor has failed.
4. Place the shop rag beneath the IAC valve. Spray the inside of the IAC valve with carburetor cleaner if the IAC valve's plunger did not move in Step 3. The carburetor cleaner will remove tar or other debris that may cause the IAC valve's plunger to stick.
5. Allow the IAC valve to dry, then repeat step 4. Replace the IAC valve if the plunger still does not move when the key is in the "On" position.
Tags: control valve, idle control valve, throttle body, valve plunger, carburetor cleaner
