First some background:
I bought my car in late April of this year, ('89 GTA Trans Am, L98 automatic trans, 3.27 w/posi). At the time, the seller said there was about 10K on the rebuilt motor, that was about 6k ago (there is 159,6xx on the clock). Ever since I got it the SES light would come on and go off while cruising at a steady state(stays off in city traffic) above 40~45mph. This has been solved recently by connecting the cut O2 to ECM ground wire (its tan and runs in the harness in the firewall), then letting the computer 'learn' to use the o2 sensor again (I replaced it before I realized the computer needed to learn).

Now, when the engine is cold it has an inconsistant idle, sometimes stalls (both in P and in gear), surges (sometimes strong enough to lurch the car violently), will also feel low on power occationally (for a few seconds, also will do this quickly, bucking the car) and generally runs mildly roughly. Before the sensor was reconnected, the only time it would stall was after it idled for awhile then put in gear. Once it warms up though, it runs really smooth and doesn't seem to missbehave at all.

One thing that I need check out is 1/4 mile times with the o2 reconnected. I was hoping that it was the culprit for my slow times (16.0s @ 85ish), but it really doesn't seem any faster.

Sorry for the length and any spelling/grammer errors, but this is really getting on my nerves and the tech that is helping me is running out of ideas (he isn't specialized in GM EFI, knows old school GM and Infinitys). He does have a scanner that we hooked up to watch the computer learn to use the o2 sensor. I am hoping some TPI wise people can help out.

Edit: My friend (the tech) suspects the computer and/or injectors. There is also a slight miss as well.

 

Update: The car is acting slightly better, it doesn't hunt for an idle as much or stall out. I think that the ECM needed some more learning time. However, it is still slow and seems to drop power and buck while cold.

Someone has to have some good advice for me. Help, please

 

An 89...so you're maf....whenever I hear your symtoms the first thing I suspect is the maf...
I need to replace mine again too! It won't always set a code, but makes it stall out/surge etc. Try unplugging it and see if it helps. Also I'd check the iac-give the passage a good cleaning and make sure it's actually working. The scan tool shows what the iac is commanded to; not what it actually is doing.
Good luck!

 

Thanks for the info, I'll be doing an intake/ injector cleaning on monday. I figure, if its good enough for Infinitys, its good enough for me. While the throttle body is exposed, I'll shoot it with some cleaner too.

Is there any way to check if the maf is or is not malfunctioning

 

Disconnect the MAF while the car is running and if it acts like it wants to cut off and is running very rough then the MAF is good. Now if it can still run with the MAF sensor disconnected (it will run slightly worse but not that bad) then the MAF is bad. This tests if the car can run without the MAF, which it should not be able to do. I did that test on the car before and it was good back then.

 

I HAVE THE SAME PROBLEM! I have an '85 iroc 305 tpi. When the car is cold...i have a lot of jerking problems. Also i adjusted the idle pin and changed the throttle spirng because the throttle seemed sticky. The car is now set to idle at 650rpm but it doesnt at times. most of the time it still finds a way to idle at 1000rpm. also the throttle is still sticky sometimes. I'm kind of starting to wonder if this is the culprit for my gas guzzling problems. I spend around 60 dollars per week on GAS! Another thing i noticed is that i can watch the gas meter drop when the weather is hot. Seems like im getting 8 miles per gallon or somethin like that. I really need some help. Gotta be honest, dont really know what im doin. But i would love to learn.

 

I did this about a month after I bought it, and it would idle ok, but any more than that and it would die real quick. I'll try it again this week, see what happens.

As an update, it seems to run better and better, but the milage is alsotaking a hit at the same time. I'm going to see what the next tank is like before i freak out though, as the computer was doing a lot of learning on the last one.

 

anyone know of a site or something with a complete diagram of what is wat in the engine compartment?

 

Well, last weekend was a pretty busy car orientated few days. Last friday I went to a local drag strip, hoping that the cooler weather would help me. Well, it didn't, in fact taht night my car was acting worse than ever. In the staging lanes it kept surging strong enough that I had to keep the brake on HARD, or hit someone. Also, after a few unchecked surges it would stall out. At the line was no better, as one time, right after I staged, it surged hard enough to put me through both(!) staging lights, I then proceeded to reverse back to where I was before, at which point it promply stalled. I'm glad my windows were rolled up, maybe the started couldn't see my face.

The biggest kick in the teeth though, was that going down the return road and picking up my time slip, it ran perfectly (smooth, no stalling etc). I do have a suspicion that the bag of ice I put on the intake triggered this somehow, just a thought.

Saturday I took it to a shop to have the sparkplugs changed (I did the #1 plug on the friday, then ran out of time, patience and knowledge). I was hoping that bad plugs were at fault. They were not, as they all looked pretty good.

Sunday I went to an SCCA autocross and was one of only 2 3rd gens, and the only v8 thirdgen there. Anyway, while lined up for both tech inspection and staging it was doing the same as at the strip. The one exception to this situation was right before I went on my first run. Just before I went, it smoothed out perfectly with no warning at all. I was holding the brake and gas enough to keep the engine running (bouncing between ~800 and ~1100 rpms) then all of a sudden it sounded better and held a rock solid 950rpm. At the same time the SES light came on and stayed on for the first 3 or 4 corners.

I checked the code later and it was 45, a rich condition. I also disconneded the MAF sensor, as suggested above and it ran about the same and i drove around for 2 or 3 days without it. Once i reconnected it, the engine seems to run a little better, though will still stall out on occasion, mostly when cold.

Any help guys? sorry about the length.

 

Consider checking or replacing the distributor. My brother had the same problem for about a year (bad idle) but when he was installing the Accel intake he noticed alot of play in the distributor. Also check the Cap and Rotor for corrosion.

 

Its funny you suggest that. Yesterday, after i posted, i decieded to check the injectors for functionality, then the distributor cap for cracks. The post for the #2 cyl was all green (corroded) and the contacts were dirty on the inside of the cap, so we cleaned them up. Although it runs a little better, it still stalls and isn't quite right, I guess a new cap, rotor and set of wires is in order before next spring (its going into storage sooner or later).

BTW all the injectors seemed fine except for the the #1 cyl, that bled off pressure after 2 consecutive tests. New, or reconditioned injectors, seem inevitable now too .