RPMs changing

[Tedders]

Hi, y'all.

So I have a '93 Gen 3 SE (6 cylinder manual 5 speed)where the RPMs do some odd things (Well, maybe; mabe not):

On startup in the cold, they go up to 2,000 and stay there for about 3 -5 minutes.

When I go to shut down the engine (I'm at a stop), they arise from about 750 to a little above 1,000, and then fall again to 750.

At idle with the engine warmed up (like sitting at a light), they're about 750. Then they drop a bit, the engine runs a tad rough, and then they arise again to 750.

After an acceleration and then coming to a stop (engine revved to about 3,000) the RPMs drop to a little above 1,000, pause, and then drop to 750.

Are these common patterns or is my engine possessed? If the latter, any ideas to exorcise it?
T'ank yew all.

Drive laughing!

Tedders

[tacomonkey69]

ive got a 97 v6 5spd and my car does the same thing on a cold start. but it drops back down to 1000 after driving for a while. i only noticed this after i installed a cold air intake on my car so maybe that is what causing my car to rev high on a cold start.

[ECale3]

my car idles at 850rpm after it warms up. cold start it idles at 1100rpm. At extremely cold start it idles at 2000rpm.

[toyomoho]

The engine control system has an idle up mode to increase RPM when cold. Idle is controlled by the IAC valve that can get dirty over time, try cleaning it. Be sure to use a cleaner that is safe for use with plastics.

[Tedders]

Hey, thanks. Good suggestion.

But what is the IAC valve and where is it located? (Dare I say it?: It sounds like an easy fix!)

Drive laughing!

Tedders

[Eye8Pussies]

if you ask me, sounds like the iac as well

the iac is located right under the throttlebody

you can take the intake hose off and then just spray plenty of throttlebody cleaner on to the bottom of the TB and it will drain into the iac hole, hopefully cleaning it