Hi everyone.

I'm a new member here and just got my first Third Gen, a 91 GTA with the LB9 305, off a fellow forum member. This is my first foray into TPI cars. The GTA is stock with only headers, and a 3in exhaust with no cat. I got all of the service records with the car, and some of the sensors were replaced. Right now, its having a slight stalling problem.

The car starts and idles fine at the get go. When I'm backing out of a driveway or parking spot, the idle will drop to 600rpms and then stall out. The SES light comes on right after this too. Also, if I'm sitting at a stop light thats on a slight grade, the RPMs will start to bounce a little bit and it'll get the same symptoms as when I'm backing out. And it will stall out in drive too, not just reverse. It also seems to smell like its running a little rich, too. I don't know if its related or not. It could also be that I'm not running a cat. I'm pretty stumped right now, but I think I have my problem narrowed down to these things:

MAP sensor
Fuel Filter
IAC
The fact I don't have a cat
Possibly the EGR valve

Like I said, I'm new to the TPI world (I am well versed to the 4.0 I6 in Jeeps and GM's 3.8L V6) and I'm really stumped. Please help me out guys. I want to get this problem situated before I have to back to school from Spring Break.

Thanks for your help. I plan on being around the Third Gen community for a long time coming.

-Justin

 

bump

 

first thing to do is pull the error codes and post them here

You also may want to check all your vacuum lines.

 

Ok. I checked for codes today and all I got was Code 12. So its not throwing anything right now. But some new symptoms are showing. The car will now stall out sitting at stop signs or stop lights. It really gets bad if I'm cruising down the highway and then have to stop. It'll idle fine for a few seconds and then the idle drops until it stalls out. I looked through the old records and the TPS was replaced less than a year ago.

The guy at Advance Auto (who has worked in parts most of his life and has owned a few Third Gens) said it could be the fact my torque converter isn't unlocking when I'm coming to a stop. He suggested that it may be the Transmission shift down solenoid (or something to that effect).

I'm honestly stumped at this point and I'm going back to school tonight, so I won't be able to work on it for awhile.

 

if this were the case you would notice the stalling condition would be kinda violent.imagine stopping a stick car without pushing clutch in and taking it out of gear.i would check tbody for buildup around plates and check for vac. leaks and iac operation

 

Thanks. Are there any certain vac lines I should check? And with the IAC, how would I check it? Just pull it out and check it?

 

check all vac lines you can see and listen for any leaks while engine is idling.if i remember right iac should cycle while aldl is jumped like you would do when you checked for codes.someone else may know for sure?

 

^Thanks for the info. Since I'm away from the car, my dad is doing all the searching and what not right now. He's going to take it for a spin later and try to get it to stall and then connect the code reader to see what code it throws after it stalls.

He took it out of the garage today and said that its stumbling under idle now, almost like its not getting enough fuel, and then catching itself. Could this be a fuel pump on the way out or an injector dying? I'm going to check them with a multimeter when I go home this weekend to know for sure.

Thanks again guys.

Edit: My dad also said it seems to be running rich. This is really starting to get my stumped....

 

There's is an easy way to check your torque converter, I have a friend who is a certified transmission mechanic, he told me this.

get the car going at highway speed 55-60 mph, while holding the gas with your right foot, lightly tap on the brake with your left foot, your tach needle should jump up 2 or 3 hundred rpm then come back, this means that the tcc has disengaged when you stepped on the brake.

Also, if you don't have it already, you may want to put a heated o2 sensor on there.

 

Thanks for the tip John 89 Formula. I'm going to check that the TC when I get home Friday.

What do you mean by heated O2 sensor? The headers and everything has been replaced with MAC shorty headers and and MAC exhaust. Could a screwed O2 sensor be the culprit?

 

You've got all the exact same symptons of mine. I've yet to figure it out either. And it just keeps getting more symptons growing on it. One time I couldn't even get any power on the way hom and got stuck riding on the shoulder of a 55 mph speed zone road.

Does it not hook up or give you any power (practicly stalls without shutting the car off) when you stomp on the gas to go? (With the car in gear, that is.)

If you got a vacum leak I'm told that could also clog your Catylitic converter...

 

On some headers, I had Edelbrock on mine, the o2 sensor is too far downstream and dosen't get hot enough which can create a false lean condition, so the computer richens up the mix.

I had to install a heated o2 sensor, as well as wrapping the headers to try to keep the heat in. Even with this, on really cold days it would still throw a lean error code.

 

FlameFeather: Mine will still give me power when I stomp on the peddle. I may throw the catalytic converter back on it to see if that solves the problem.

John: That makes sense. I'm going to check the condition of the 02 sensors Friday. Thank god for nice weather, finally. Mine isn't throwing any codes though, even after it'll stall out (my dad checked it last night).

I'm also going to throw my new spark wires on it too just for good measure.

Thanks again guys.

 

Hey everyone. I just wanted to throw out an update.

I haven't had much time to work on the car or address the stalling issue. I've been too busy finishing up my last year of undergrad and graduating from college. Tomorrow will be the first day I take a crack at it. I'm putting a new IAC in it on a hunch that that is whats wrong.

I ruled out the injectors because I ohmed them all and got 15 for each. But a few more problems have popped up. If I'm stuck in traffic, my temperature will go well above 220. I'm going to check to make sure my fans are kicking on. Should I check the coolant temp sensor too? Where is it located? Also, the car seems to be running rich lately. Could it be connected to the stalling issue? And does anyone have a write up on how to install and set-up the IAC?

Thanks again,
-Justin

 

When my car would idle but stall as soon as I put it in gear, it was my coolant temp sensor. Replacing that anyways would probably be a good idea, it's pretty cheap.

 

Thanks for the info. Where is the coolant temp sensor located? Is it right in front of the block under the TB?

I put the new IAC in and it cured 90% of the problems. Now it seems like I've developed a slight miss occasionally, a rough idle, and an overheating problem in traffic. I think the idle might be connected to my TPS. It was replaced last year by the P.O., but when I replaced the IAC, I pulled it too and managed to drop it off my work bench. The rough idle will cause the car to surge forward a little bit, making me think its the TPS.

Any more info would be GREATLY appreciated. I gotta get this thing totally mechanically set before I start the body work.

 

ahh, I apologize, it was my TPS that was making it idle really bad. as soon as i replaced my TPS my coolant sensor went bad so that caused my car to have a no start condition. i just got back from a party last night when I answered so I wasn't thinking to clearly. have you double checked your timing to make sure it's set correctly? it should be 6* with the est wire unplugged when you are setting it. Also, when you are dealing with the IAC valve and the TPS both should be set to there proper settings. There's some instructions around the site on how to set them properly, but you want to make sure you have your timing set properly first so you rule that out as the problem. When I have more time tomorrow, I can look for the instructions on setting them if you can't/don't want to find them. The overheating issue I'm not quite sure about, the only thing I could suggest for that right now is make sure your fan is turning on, and make sure your coolant hoses are set up how they should be, and make sure you have coolant in your radiator. Btw, how hot are you actually running?

 

hahaha. Its cool. I've done stuff like that before.

The previous owner put a new TPS in it last year, but I'm wondering if it went bad because my IAC has been bad for God knows how long and I just replaced it. I got the Coolant Temp sensor and I'm in the process of putting it on right now, but I hit a snag. The TPS wire connector's plastic tab snapped off when I was pulling the throttle body. Let's hope that zip tying the connector to the TPS works. When it rains it pours....

I looked for the way to set the TPS and IAC, but I've come up fruitless. If you could point me in the right way, I'd be extremely appreciative.