idle control valve - what does it do?

[funcrew]

What would be the symptoms of a bad ICV? What does it do, anyway? It's $120 for a new one, and I'm skeptical that the DIY cleaning-out routine would last long. Failed smog test is my reason for asking.

[gtdragon980]

from my experience with it, usually a bad icv causes your idle to bounce around 1000-2000 rpms or so.

[payney8]

idle control valve...... controls the idle.......... It opens a air path at idle due to the fact the throttle butterfly is shut. This only allows an idle amount of air flow. If its screwed depending on which way it can cause the car to rev or it can be hard to start. Take the pipes of it and turn your ignition on you should hear it buzz and have a look through it

[jlevie]

A bad idle control valve could be a contributor, but by itself it isn't going to be the cause of a failure to pass smog testing. Without knowing what part of the test the car failed I'd suggest that you:

1) Have the intake smoke tested and repair intake leaks as indicated.
2) Replace the O2 sensor if it has 100k or more on it.
3) Run the fuel system tests in the Bentley
4) Replace the ignition wires, cap, and rotor, and plugs
5) Adjust the valves

[funcrew]

Thanks to all for the information.

A bad idle control valve could be a contributor, but by itself it isn't going to be the cause of a failure to pass smog testing. Without knowing what part of the test the car failed I'd suggest that you:

1) Have the intake smoke tested and repair intake leaks as indicated.
2) Replace the O2 sensor if it has 100k or more on it.
3) Run the fuel system tests in the Bentley
4) Replace the ignition wires, cap, and rotor, and plugs
5) Adjust the valves

2,4, and 5 are done. I'm reverting from PO-installed 19lb injectors and chip to all OEM. Also installing a new intake boot since the old one feels brittle. It's possible the newish O2 sensor might be shot from it running rich for a while.