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Idle Surge

Posted: Mon Nov 21, 2005 1:18 am
by RedRacer
Engine revs constantly while sitting at idle? Stopped in traffic, etc.

It's probably the IAC or Idle Air Control Valve.

The IAC has a seal inside that will unthread its self thus letting more air in when its not suppose to and cause the ECU to get confused leading to the surging idle. Sometimes it just gets dirty and needs to be cleaned.

The 4th gen IAC is right under/near the throttle body at the intake. It has two hoses attached to it and screws to hold it in place.

Remove the IAC and open the cap which consists of a few screws and screw the seal back in or take the spring out and clean it and the valve itself with some injector cleaner and put it back together. This should stop your surge.

There are a few other things that can cause this same symptom. Ranging from a hole/leak in a vacum hose to air bubbles in the coolant.

If the IAC fix doesn't get you straight, try checking all the vacum hoses and try bleeding the coolant. These too could solve your problem.

-- Josh