View Full Version : my 89 SC is having trouble idleing

02-25-2005, 12:16 PM
I changed the IAC valve, TPS, and baro sensor, cleared the computer, and the car still wont idle, but it runs fine. any suggestion's anyone??

02-25-2005, 01:48 PM
If you do a search of the forum you'll find a lot of posts concerning idle problems. You have to make sure everything is adjusted properly and putting out the right voltages to the EEC. Once you're sure that you have all the components functioning properly in the intake system, ignition system (including timing), and the fuel system (fuel pressure and regulator), then you can look for the source of the poor idle. At this point, doing a simple "Idle Relearn Proceedure" may clear up idle problems. But a worn or malfunctioning mechanical device such as an injector can cause problems.

Something as simple as a dirty, worn, leaking injector can cause a poor idle, but yet run "good" above idle. The way the car is acting at idle can be of help in determining the source of a poor idle. An intermittent stumble can be due to a dirty injector not spraying, but instead "dribbling" gas at idle. The EEC will try and adjust for this, but it can't eliminate it entirely as the fuel delivery is not consistant.

In my case, I'm considering pulling all my injectors and having them tested.

My idle has improved considerably after having done all the above checks and adjustments (see previous posts), yet there is still a slight intermittent stumble upon startup, that gets better as the car warms up. I've uses a good injector cleaner a couple of tanks ago, and noticed imporved throttle response since. Still, I believe my injectors are in need of replacement, as well as my O2 sensors for better gas mileage (I"m still not convinced that O2 sensors help idle, but I'm open for comments).

Aother thing I have yet to adjust/check are the rocker arms for too much play or too tight. Bascially, they all need to be the same, and one or more may be loose enough to have an affect upon idle.