My 89 GTA idles weird. It doesn't do it all the time tho...

It usually starts up ok when its cold, and idles normal (700, 800 rpm). After I drive it for a while, it idles around 300, 400 RPM when I come to a stop, and sometimes stalls. (a couple times its stalled out causing me to have to steer the car with no power while trying to restart it in traffic ) If I turn the car off and try to restart it, it usually idles really low (200-400 rpm) and will usually stall unless I give it some gas. Throughout this the “check engine” light is on sometimes, sometimes not.
If I continue driving for 5-10 minutes after this happens, it will usually start running great again without any problems. Once the car is running for 15-20 minutes, it runs very well, no matter if its stop and go driving or highway.

The car has 196,000 kms (122,000 miles). The previous owner parked the car for 2 years, so I know its probably in the need of a good tune up. It also has bad valve seals, and the cats are shot. Anyone have any other suggestions of some other things I should repair/replace/service? Obviously plugs, wires, check distributor. What else could be causing these problems? I’ve read that it could possibly be the idle air control.

I do not know much about TPI engines or the emission equipment on this car, so any help or advice is greatly appreciated. Hopefully someone can point me in the right direction. Thanks.

 

Many idle problems on EFI engines can be traced to contamination of the throttle body and the IAC system. Search the archives for information on throttle body cleaning.

 

Ok thanks... I'm going to be picking up new plugs and wires and rotor and cap for it tonight... that's a good place to start too... I had some bad idle problems on my V6 'bird a couple years ago and it was wires and cap...

I'll search the archives for some info on IAC and throttle body cleaning... is there any other things that I should check out (or specific things I should search for info on)

I appreciate the help guys... TGO is a great resource....

 

I've seen a lot of posts lately describing similar problems to the ones I've had lately...

Anyways, just an update... the other night I replaced the distributor cap and rotor... cap wasn't too bad (a little corroded, but not bad) but the rotor was completely shot. After replacing these 2 items, the car runs much better, and after 2 days worth of driving hasn't stalled (or even come close to stalling) once. It still has a bit of a rough idle... when I get time I'll be replacing the plugs and wires, and cleaning the IAC too... part of my problem may also be the exhaust (small exhaust leak at cats).

Does anyone have a picture of the IAC? Cleaning instructions?

 

Don't forget the Oxygen sensor. It's cheap and necessary. Everybody seems to recommend a Delco vs the Bosch. It'll take all of 5 minutes to replace - it's in the driver's side exhaust manifold. There's a special 7/8" socket to do it with a ratchet, or you can use wrenches, but it may be difficult due to lack of room to turn it, but not really. New ones usually come with anti-sieze on them.

 

If none of that does it, go for the EGR valve next....

 

The previous owner said the egr was replaced about 2 years ago.... but then again who knows if he's telling the truth. So far I found out everything he's told me about the car was true... but just cause it was replaced doesn't mean its still good (like I said before, car sat for a while)

 

Hey guys... also, once in a while when I downshift, you can hear the car backfire... sounds like a pop from the exhaust system... I'm guessing its unburnt gas igniting... I'm assuming this is related to the idle problem too... more suggestions?

BTW I'm losing my job in October, so I'll have more time to actually work on my car... I'm just trying to find out all the things that could be causing my problems so I know what to start working on when I have the extra time.