91LE rough idle

[Colov99]

I have a 91 LE and it idles very low and already has stalled out from idling. I think its my idel adjustment valve but I'm not sure where its located. What it does is the rpms drop realy low spike and then drops and dies.
Any help would be great.
Thanks
-C

[randman1]

The Idle Air Controller is located on the throttle Body itself. There are three things on the TB:

MAF sensor is a black rectangle about the size of a pack of cigarettes seen on the top.
TPS is exactly opposite of the throttle linkage.
IAC is the only one left and should be kinda on the bottom side under the TB intake opening. You can just remove the IAC and clean both it and the hole it came out of but you can do a better job by removing the whole TB. If you decide to just remove the IAC, place a rag under the IAC to catch the screws. They are very easy to lose.

If you remove the TB, you will need to drain a little coolant as there is a passage in the TB. Once it is removed from the car, remove the MAF, TPS and IAC. Place the stripped down TB into a shallow tray for a bath. Grab some STP throttle Body And Intake cleaner and an acid brush or similar small brush and clean the hell out of it.

Before:[Note: This TB from a 93 and placement of the components are slightly different than yours]




After:



The MAF can be cleaned by using QD (quick dry) Electronics Cleaner. Reinstall the three components back onto the TB and reinstall onto the motor. Don't forget to top off the coolant when done.

This is pretty good general maintenance and may solve your problem but there are a couple other things that could cause poor idle. We can start with this though.

[Colov99]

Thanks. Ill go attempt that later.. IE when its not raining and I can get all the tools.. (stupid college campus)

[Colov99]

Update::
now whenever I take my foot off the accelarator the RPMs drop to about 500 or lower and the car stalls out. So to drive today Ive had to put it into neutral at lights to keep revving the engine. I will try what randman sugjested but if anyone has more specific details on how to remove it that would be appreacated. Since I am attempting to do this repair on a college campus. Thanks
_C

[Colov99]

Update agin: took out the IAC and briefly cleaned it with what i had. Car now runs and idles going to take it home and replace the airfilter and clean everything else out better. Thanks for the help
c

[randman1]

Was it filthy like what is pictured above?

When is the last time you had a tune up? Might be time for plugs and wires along with that filter.

[Colov99]

I didnt take off the TB just the IAC and it was pitch black.. Im not sure when it had a tune up but after cleaning the IAC the idle is smooth again and the car still runs great, and is getting around 25mpg. So I dont think it needs a tune up anytime soon.
-c