Idle problem

[ttbnate]

I've got a 92 Achieva with the 2.3L 4 cylinder. After the car warms up, the idle will raise to about 1600-1800.

I've noticed that this is a degenerative problem, and over time it is taking less and less time for the idle to start going out of control.

...anyone have any ideas as to what could be causing this?

[GTP Dad]

Welcome to AF!!

Check for a vacuum leak either a bad hose or around the intake manifold. Rising idle like you indicate usually indicates that there is air entering the engine at a place other than it should. Also check the throttle body and make sure it is tight, that can cause this type of problem. The other is a bad throttle position sensor. If it is sending the wrong voltage to the ecm it will cause idle to be too high.