how do you tell if an idle air control valve is bad? my engine is idleing about 1000 RPM and i was tinkering under the hood the other day when the car was idleing and i unplugged the iac and it didnt change the idle at all, is this an indication the iac is bad?

 

If you really want to tell if it's bad, jumper the ALDL to pull codes, and turn the key on. Put a couple fingers on it. If you can feel it vibrate, it's good. You may also be able to hear it buzz for a couple of seconds when you turn the key off.

 

i hear a small clicking sound when i turn my ignition off, also im getting no codes.

 

I didn't say to look for codes, I said to set the ALDL up to pull codes, turn the key on, and put a couple fingers on the IAC to make sure it's working. It'll be vibrating if it's at least trying to work. Setting the ALDL for codes does a couple things besides blinking the SES light... Turns on the radiator fan, closes off emissions solenoids (or does it open them? Either way, the ECM does the reverse of what's normally done KOEO) on the EGR and charcoal canister, and the ECM also closes off the IAC passage by extending the pintle inside the IAC (which is why the ALDL is jumpered for about 10 seconds before the IAC is disconnected to set the base idle speed).

The other way to tell if it's working is to watch the engine speed as the engine warms up. It should start about 1200 when cold and drop to about 8-900 when hot, most of the difference made at about 160* coolant temp. If the engine speed increases as the engine warms up, there's a problem.

 

mine idles 1100 or 1000 cold, and ok ill do this friday or saterday when its not raining out, i hope its not raining those days because i need to replace a brake line.