I have a 94 3.4 that's idling too fast. I took out the IAC and retracted the pintle to 28mm, removed the battery and put it all together. This seemed to work but was back to fast idle again in a couple days. I then installed a new one and that curred the problem for about a month, but now it's back to fast idle again. Anyone know what else can be wrong? Appreciate the help, Thanks.

Check for a vacuum leak at intake gasket(s) or throttle body base gasket...

Do you have a diag tool connected? That will raise the idle.

-dnult

Welcome to the Club !! You'll find alot good info here plus good guys/gals. My 2 cts. on your problem: 1. Agree with Don & dnult. 2. Is base idle set too high? Place ecm in diagnostic mode. turn IGN on, this will extend IAC to seat, turn off IGN, disconnect IAC, remove diagnostic condition, start engine. This will be base idle. Compare with service manual. Set accordingly, turn off engine, plug in IAC, remove fault codes. 3. Could it be there may be another sensor at fault, causing the BLM's (block learning modules) to fill up with faulty info thus causing high idle? 4. ECM Coolant sensor faulty, or its wiring faulty. 5. EGR valve leaky?

Just food for thought...........

Appreciate all of your replys. I'm hoping to have time this weekend to do all of your suggestions. I will post results.

I'm not quite sure how to put ecm in diag. mode and to set the base idle. I know that after adjusting the pintle to 28mm it idle's at 950 - 1000.

If anyone else has suggestions, please do post.

Thanks

You might try http://www.thirdgen.org There are several forums there that might be able to help you out. I have experience with 84-87 model years so I'll say this.

On the 84-87, Turn the ignition on and put the car in diag mode by shorting two terminals on the diagnostic connector. The computer will retract the IAC pintle. You then disconnect the IAC, start the motor and mechanically set the minimum idle to around 750 RPM I believe. Once done, the throttle position sensor should be adjusted for around 0.5 - 0.7 volts.

Then the motor can be shut off, IAC reconnected, and taken out of diag mode. Drive the car around a bit until warm and the computer will re-learn idle.

Now, I hope the 94 is similar to what I've described. You should consult a service manual or perhaps someone will chime in to correct or confirm.

Happy 4th graemlins/beers.gif

-dnult