2002 Pontiac Grand Prix Intermittant Stalling

by Jason
(Buffalo, NY)

I have a 2002 Pontiac Grand Prix and I love my car but recently I have had numerous problems with it regarding my car stalling. I have taken it to 3 shops including a dealer and no one has found the problem. At first my car seemed to be running rough, shaking a little and occasional it would shut off for no reason. A friend of mine seemed to think it may be due to the plugs and wires at first. I replaced them for the 1st time on the car since I bought it and it has 50,000 miles on it so it sounded like a good idea. We ran it after and it stalled again! I have no engine lights on it from the computer. I took it to a shop and they looked over the car and could not find any problems. They seemed to think it had something to due with the security system and advised I take it to a dealer. I had it in the dealer next for a week and a half and they could not find any problems. None of the shops were able to recreate it enough to find the problem, but it did continue to happen. After having it in the dealer for a week and a half I decided to take it away from the shop because they gave me no information except they wanted to try and replace the mass air flow sensor but they were not sure! I took it to another shop because they seemed to think it was a fuel pump resister on it. This 3rd shop looked at it for 2 weeks and determine that there was no fuel pump resister on this car and could not find the issue but they thought it may be a crank sensor. They replaced the crank sensor and told me to drive it for a week and if it worked then great, I would pay for it. I drove it for 2 days and it worked great and then when i was driving home it stalled again! All electronics run fine but the engine shut off. Took me 2 times and it started right back up. I am running out of ideas and not sure where to take it or what to look for. Any ideas would be great! Any additional information I can provide.....please help!!!!

Steve Says,

Thanks for your question. It looks like you have a tough one! First of all I'm going to assume that you have some mechanical ability. If not then you might want to find someone that can try some of the things I suggest.

There are several things that can cause this type of problem. The first is the crankshaft sensor. Since this has already been replaced I'm going to assume that it is good, but if they did not use a good part, did not install it correctly or if the magnet behind the sensor is bad then this could still be the problem.

The first thing you should try is cleaning the Mass Airflow Sensor. Any good auto parts store will carry MAF cleaner or electrical parts cleaner. You will have to remove the MAF and clean the small wire being VERY careful with it so you don't break it. These little wires get dirty and can cause the same symptoms that you describe. One other thing you can try is running it with the MAF unplugged. This will make the computer use its backup reading for the calculations it needs instead of using the live MAF reading. If the car runs better like this then there is a good chance that the mass airflow sensor is bad.

Next, you should clean your EGR valve. The Exhaust Gas Recirculation valve sometimes will get sticky and cause more exhaust gasses to go into the engine that should which makes the fuel mixture lean (too much air, not enough fuel) and cause your engine to stall. ERG sensors often get gummed up with carbon and stop working correctly. You can remove it and clean it with any type of lubricant then reinstall it. You should be able to re-use your EGR mounting gasket. If this seems to help the problem then you will probably will want to buy a new one in the near future as this is a temporary fix.

If the stalling mainly happens when the car is at or near idle you might have a problem with your Idle Air Control valve. The IAC will sometimes get sticky as well and cause a stalling condition. There is really not good way to clean it, but you could try lubricating it with penetrating oil.

These are my first thoughts. If you try them an nothing works feel free to leave me a comment with updated info and I'll help you more.

You should really find a good repair shop. Any good shop should be able to trace this problem down...however if the shop cannot get it to stall when they are working on your car then it would be hard for them to diagnose so you should try and pinpoint exactly when it stalls so you can tell them what to do to make it stall.
I hope this has helped!