If your inactive engine has not changed, you may suspect that it is the IAC. If it works properly, stopping it would cause panic to your inactive engine. Normally, if you turn on your car, the inactive air control valve will increase and decrease the rpms engine slowly.
How to Check an Idle Air Control Valve
- Open the hood and remove the screws holding the idle control valve to the throttle body on the back of the engine.
- Unplug the electrical plug running to the control valve.
- Pull the idle control valve off the throttle body and turn it over to expose the valve openings.
- Turn the dial on the voltmeter to "Ohms."
A defect in the idle air control can cause poor idling or even stalling of the engine. A coating of carbon may accumulate in the idle air control, and cause malfunctioning. It must, therefore, be cleaned at regular intervals. Unscrew the idle air control valve by removing the screws that hold it to the throttle body.
The engine may be stalling because it isn't getting enough throttle opening. The cause is often a problem in the idle air control system. The first thing to check is the intake vacuum with a vacuum gauge. An EGR valve that is leaking can also act like a vacuum leak and cause a random misfire.
How do you reset the IAC valve?
- Depress the accelerator pedal slightly.
- Start the engine and run for 5 seconds.
- Turn the ignition switch to the OFF position for 10 seconds.
- Restart the engine and check for proper idle operation.
Hi There, It sounds like you may have a dirty or failing idle air control valve causing your engine idle to fluctuate. When this happens, the job of the idle air control valve is to bring this deceleration down to a slow and smooth idle rather than suddenly cutting off the fuel supply causing the motor to die.
In general however, there are two problems that can cause engine idle speed to fall outside of specifications: Issues with the idle control valve (or screw on a carburetor) Vacuum leaks or obstruction of fuel/air flow into the combustion chamber.
Without the IAC, turning on the AC and headlights (or some other heavy load) could stall the motor. Running with no IAC could potentially cause the car to run lean or rich while idling, give you a check engine light and cause you to fail an emissions test.
RE: Should the IAC move freely? The IAC is a stepper motor so you will not be able to manually move it in and out or it will be broken. Usually just cleaning them and the housing they sit in is good enough.
These are the symptoms of a bad or failing idle control valve
- Irregular idle speed. One of the most common symptoms associated with a problematic idle air control valve is irregular idle speed.
- Check Engine Light comes on.
- Engine stalling.
The average replacement cost of an idle air control valve is between $120 and $500. The parts could cost anywhere from $45 to more than $400, while the labor is only around $70. Of course, the labor cost really depends on the hourly rate of the mechanic.
If your vehicle has the 4-liter V-6, the problem may be a faulty idle air control valve. Whenever you start the engine, the throttle is closed so the valve meters the proper amount of air for combustion. If it allows too much or too little, the result is hard starting and often rough idle.
~20-40 on a warmed up, stock engine and stay steady. It should not swing wildly at idle. With engine cold, it will be higher, but slowly come down as the engine warms. You probably have some other problem that is causing the IAC to swing.
The idle air control valve (usually called an IAC valve) helps maintain the proper idle speed on your vehicle. 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.
WD40 should do no damage but may not dissolve the gunk in the valve. own car if need be. I'll buy carburetor cleaner and spray this at the IAC valve. WD40 should do no damage but may not dissolve the gunk in the valve.
