When my car is at idle in park or neutral the Intake Air Control Valve fluctuates, causing the RPM's to do the same ranging from 800-1200 rpm's. If I unplug the IAC valve it stays at a solid RPM. Every sensor I've used had the same activity. So the PCM is making it fluctuate, what could cause that?
My car has 240 miles.
My car has an automatic transmission.
Hi there. It sounds as though the idle air control valve (IAC) may be sticking. It is not uncommon for carbon to build up in the valve, the computer will try to overcompensate to correct the slow reaction inside the IAC, and therefore the idle will fluctuate. It would be best to observe the commands from the PCM with a scan tool if you cannot physically see if there is carbon build up. A certified professional from YourMechanic can come to your car’s location to diagnose the idling problem and assist with repairs.