Idle hunting issue

[pwpanas]

Originally Posted by Durandal

What would cause my cold starts to not idle high at all? Right now my cold starts the same as hot starts and idle at 900 instead of over 1k like it should. The IAC is used after it warms up right? Or do I have that backwards.

The IAC is open during starting and cold-engine operation. Throttle plate is sealed shut unless you press the accelerator. There should be no vacuum leaks other than the IAC. In other words, the IAC is the only path for air into the engine, so it must be open for initial idle. While cold, the idle rpm is higher (so the IAC is actually open its widest during cold idle); a/f is also richer during cold/cool engine conditions. The IAC closes a bit after the engine warmed up to reduce rpm.