Mechanics

GTP 73,000 MILES

2000 Pontiac Grand Prix

My car has been misfiring randomly after start up for about 2 weeks. It cleared up after driving for about 30 seconds and would return again the second or third time I started it up after that. It started last year at this time and was showing fuel injector #3 malfunction. A dose of fuel injector cleaner in the gas tank fixed until now. This time I had it hooked up to a scan tool and it showed that the fuel system was running in an open state even though it was at 200 degrees F. It showed no reading on the 2nd O2 sensor and randomly showed a malfunction for the same #3 injector and a misfire. I gave it another dose of fuel system cleaner and changed the spark plugs. It seemed to run smoother with the new spark plugs but the problem continued. It has run through 3/4 of a tank of fuel with fuel injuector cleaner and seems to be getting worse. It rarely stumbles during idle right after start up, but it now does it while I'm driving. If I give it a lot of gas on the highway, it will clear up, but through town it will just keep doing it until I open it up on the highway again. Please help, I already have a Jeep Cherokee that eats money, I wanted this to be my dependable transportation and not have to sink money into it all the time. Thank you for your time.
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Relliknikcuf
May 28, 2007.




No replies? I'm disappointed, I would have thought that at least one of the car experts on here would have some feedback.

I am looking for a possible solution to my problem or at least somewhere to start looking. Guess and check is not my preferred method of auto repair, especially since everything seems to be outrageously over-priced for my car.

Tiny
Relliknikcuf
May 30, 2007.
I have an '04 Pontiac Grand Prix GTP, and have had the same problems. When they started, I cleaned the injectors, changed the plugs, wires, air filter and fuel filter. Ran better for about 2 weeks, then got worse. Added fuel injector cleaner, and saw no change. Took it to a garage, and they changed 2 of the ignition control modules. Improved again for about a week, but now I am back to the beginning. Sorry - I know it doesn't help fix your problem, but might help you avoid adding all of this cost for nothing.

Tiny
Hemmema
May 31, 2007.
Thanks, that helps. Now that you tell me this, I wonder if it is a bad ground. I'm going to check the battery and ground connections. If that doesn't help, I think I'm going to pull the injectors and have them checked out and cleaned professionally, starting with injector #3. Thanks again for your reply.

Tiny
Relliknikcuf
May 31, 2007.
Replaced fuel injector, works great!
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Tiny
Relliknikcuf
Jun 18, 2007.

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