Idle Air Control Valve (IAC, IACV) Testing

Over the years, I have had to diagnose idle quality issues. In the beginning, I had a difficult time determining if the IAC was functioning. I have learned and developed three base tests that I use on a consistent bases to verify that the IAC functionality.

1) RPM climb when engine starts
2) RPM increase when AC is turned on
3) Using a bi-directional scan tool to verify control and movement of IAC

If all of the above tests pass, I have found that the IAC is behaving as it should. I have had 80% success cleaning Ford type IACs but 50% success cleaning Toyota and Subaru type IACs.

Unfortunately, this actuator has many names given to it by the different manufactures. Here are some:
* IAC, Idle Air Control
* IACV, Idle Air Control Valve
* ICV, Idle Control Valve
* IBV, Idle Bypass Valve

The following are some related videos:
* Toyota Tacoma with a hard starting issue:
* Scan Tool Discussion: