90 Grand Prix 3.1 Starting Problems

Hi all looking for some help. Here are the symptoms
Car starts up when cold fine runs smooth no miss etc...
When engine comes up to operating temp around 150 - 165 car dies.
From here it is not always the same sometimes will start right back up or other times will need to wait up to 20 min.

Once car starts again will not die and will stay running to where ever you are going.

After engine cools down 3 - 8 hours like after parked at work cycle starts again......

What has been done replaced coolant temp sensor.
Fuel presure checked at dealer dealer replace #3 fuel injector did not correct problem.

Question to check spark should I remove a plug and check for spark while cranking...

Also today was able to keep running when it came up to 165 by increasing RPM to 2000 engine was stumbling during this after engine fully warmed up is smoth and no stumble.

Thanks for any help or suggestions....

Your symptoms sound like a sticking IAC valve. It's an electric stepper motor in the throttle body that varies the amount of air allowed in during part throttle and idle conditions. The other possiblity is a sticking or bad EGR valve. As the engine warms up, the EGR opens and allows unburned gasses back into the intake stream. If it isn't opening when it should, it's throwing off the air/fuel ratio causing it to die.

Thanks for your reply.
Before your reply I replaced:
the oil sensor/fuel switch sensor (was leaking).
the ECM.
All with no positive results. After your reply I finally got a fault code 35 thrown, which for Pontiac is an IAC system fault. Pulled the old IAC valve and it was carboned up and the air intake manifold was very dirty. Cleaned it all up and installed new IAC valve. Now crossing my fingers and waiting for the best.

Thanks for your help and input. Will update later on results for those with the same nagging problem. So far so good.
9/30 Didn't cure the problem.

Update on engine dying and not restarting until cool down. Engine will start and run fine till temp. reaches appx. 160-200 deg. Engine will shut down just like turning off the ignition switch. Sometimes but not often it will start right up, most off the time I have to wait till the engine cools down to start. Once I get it started it will run fine and purr like a kitten and never stall. If I leave it sit for more than 2-3 hrs or greater odds are it will all happen again. If I keep the engine revs. above 2500 rpm the engine will stumble a few times and usually keep running. Driving or sitting in the driveway makes no difference. Symptoms seem to relate to engine temp, I can usually bet the engine will die at that magic temp of 155-165 on the temp gauge. I've replace in order: Fuel filter, CTS sensor, Oil sender(leaking), ECM, IAC valve, Intake air sensor, Map sensor. Exhaust was shot from the cat. converter back and just replaced that. Converter also needs to be replaced rattles a bit due to a problem from the previous engine. $250!! This engine was new with 125,000 miles on the car but old engine fuel, intake, sensors used from original engine. New engine has about 40,000 miles on it without any previous problems till lately.

Anyone have a clue what I'm missing that is causing this stall/no start problem? EGR valve is my next guess but car runs fine once I get past that go/no go temp. Engine does seem to run a bit hot in stop and go traffic or at a trafficlight but will come back to norm. temp while driving. Fans are working.

Thanks for any info.

my next suggestion is to check the injectors. A balance test will determine if one is way out of range from the others. They should all read somewhere between 11 and 13 ohms (I don't have the exact figures in front of me, so check a repair manual to be sure). Any out of this range need to be replaced.

i Vote........... Crank Angle sensor. No hard codes will set. The module is cracked and will expand with heat opening the circuit. one question dose it chug or shut right of?

Turns out none of those solved the problem. Finally found an unconnected vacuum line from the intake manifold to the EVAP canister purge valve. Valve is located on a bracket mounted on the rear of the engine. This valve is controlled by the ECM when the engine reaches operating temp., a certain time period or engine rpm. Funny that the mechanic at the dealership who replaced the injector didn't find it as the bracket assy has to be removed to remove the air plennum. Car has run great since then. So remember what your dad taught you KISS. Keep it simple stupid! Thanks for all your input.

The #3 injector is directly under the part you are describing, so it's the dealers fault that it was left unhooked. If you had to take the car somewhere else, or the dealer didn't find it upon a follow-up inspection, they are liable for any expense you incurred due to their negligence.

The deamon has returned. Car ran fine for 3 days (Sun.-Tues.) after re-hooking up vac. line to fuel canister purge valve. Then going to work Wed. morning engine hesitated once just as temp hit 160-170 going 40 mph but kept running. Started car after work, engine died when temp reached 160-170. Wouldn't restart until it cooled down almost 1/2 hr or better then started and ran like a top. Same problem for the remainder of the week. Let the car warm up in the driveway to be safe and every time it gets to that magic temp it will die and won't start until it cools down then will start and run like nothing is wrong. Never dies. Process repeats itself if the vehicle doesn't run after a period of time. The only difference from Sunday to Wed. is that I started out with a full tank of gas on Sunday and by Wed. had just under 3/4. I've replaced just about every sensor imaginable. Something is telling or not giving a signal to the ECM when the engine temp reaches that go/no go stage. Sometimes I can get past that temp point by keeping the engine revs at or above 2500 rpm and get a quick hesitation and the engine will keep running normal after that. I don't think EGR valve is the culprit as it idles and runs fine(engine does seem to run hotter though than the past) but it is a digital valve which I'm unfimiliar with other than what I've read in the Chiltons manual. Cracked or bad crank sensor wouldn't let the engine run at all or at best would should act up under any conditions not just at a certain engine temp.
I'm running out of ideas. There's a clue here somewhere. Come on all you Sherlock Holmes out there.

Wow, i have a 1989 Pontiac Grand Prix 2.8L and i have the same problem. The car ran fine and everything was good, until one day it just shut off on me. At first i thought i ran out of gas (but it never sputtered). I towed the car home, put more gas in and it ran just fine for about 10min, and bam... just cut of on me. I thought it was a bad ECU, so i got a new one, same problem, once the car was at normal temp it would shut off on me. Dead cut off... once in a while it would sputter but catch again if i was off the gas.

I replaced the IAC valve, the throttle pos sensor, and checked for codes... nothing. Same problem and 0 codes. Engine has 97k miles on it. I am stumped as to what the problem could be.

by the way, there is fuel in the fuel rail, good presure. When the car cuts off the injectors do not fire (or didnt before). But now, to after the car stalls i can get it to fire back up only if i floor the gas it will fire up and stay running anywhere from 1 second to 5min. If the car is cold, it has 0 problem turning on.

anyone, anyone?

You might get more responses if you start your own thread.

Maybe it's the ignition it's self?

I don't have this exact experience, but my Accent once would only stay started if I held the key in place, or if it did stick, sometimes it would just fall out of place and die again.

Have either of you replaced the ICM (ignition control module)? If replacing the ECM didn't fix it, the ignition module under the coil packs would be my next guess. IF the ECM doesn't receive a pulse signal from the ICM, it will shut off injector pulse to prevent flooding.