I need help. I have replaced the IACV twice with brand new parts and they have both gone out with in a few days of being replaced. They do throw an engine code. My idle is only jumpy when the motor is cold. If I let the car idle too long, at normal idle, the motor will start surging around 1500 RPM. If I hold the idle around 1500 RPM when stopped I have no problems. I have talked to several mechanics and have paid for diagnostics once, but the darn thing still doesn't work. Does anyone have any advice?

 

Any vacuum leaks will make the engine idle too fast. The computer then throws a code, which is described as "IACV". But actually any time the computer can't control the idle (due to air leak or perhaps a bad IACV), you will get that code.

I think those have a mechanical fast idle valve on the thermostat housing. It basically causes an air leak to make the engine idle faster after a cold start. The valve is plastic and very easy to break. But you should check all the vacuum lines connected to the manifold. Pinch them off while it is idling too fast and see if it slows down.

 

Could be a problem with the IACV wiring or the ECU. Look for an open or short in the two wires running between the ECU and IACV. Alternatively, one pin from the ECU may not be providing 12V and the other may not be serving as a proper ground.

No fast idle valve on the D16Y8.

 

Thanks for the help guys. I changed a very clogged PCV valve and then cleaned my IACV and reset my ECU and so far so good. Maybe the clogged PCV valve was creating some kind of issue. I will keep an eye on it and post up if anything goes wrong.