Pontiac Grand Prix stalls when warm

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    • #11281 Reply
      Anonymous
      Inactive

      1999 Pontiac grand Prix 3800 engine-dies when warm, starts and idles fine when cold,after 10 minutes, it dies. I have replaced the ECM, 2 coil Packs, both o2 sensors, fuel filter, fuel pump, plugs and wires, IAC, TPS. Pulled the pre-cat O2 and it still would not run when warm.

    • #11051 Reply
      Anonymous
      Inactive

      I have a 1999 Pontiac GTP I have recently replaced the intake and upper plenum gaskets, injector O rings replaced, flushed and refilled the cooling system, changed oil and filter, new radiator hoses, spark plugs and wires, new battery, replaced the TPS and cps as well now here is the issue.

      My car will drive perfect, smooth and wont miss a beat. Then all the sudden from time to time the car acts as if its starving for fuel and dies wont start until it decides its ready to be driven again. I took it to a mechanic and that’s when he replaced the sensors i cant retrieve any codes because my computer or pcm cant connect with the code reader. It powers the scanner but that’s as far as it gets. I have a viper alarm installed and the mechanic went over the wiring and didn’t find any problems he disconnected the alarm and the car ran perfect…. for 3 days.

      My mechanic prompts me to have the pcm reprogrammed or replaced but he isn’t sure he says I do have fuel pressure but the injectors simply stop pumping fuel I use only premium chevron gas and its always full I am totally stumped and need any advice will be more knowledge than I have now.

      • #12884 Reply
        Protech
        Guest

        Sounds like an odd problem. I’ve never seen a vehicle where the injectors just stop working all of a sudden. Are you sure that’s the problem? Maybe have your mechanic do an injector balance test or flow test. If it’s something that is affecting all six injectors, then I would say it’s a wiring problem or PCM issue. Hard to say without actually seeing a scanner with the car running.

      • #12885 Reply
        James
        Guest

        Is the pcm the same as the ecu? and if it is, say i were to buy a new ecu can I install this myself or would the dealer need to install it

      • #13721 Reply
        Protech
        Guest

        Yes, PCM and ECU are the same thing….dealer would have to program it and install it. I would recommend only using GM parts!

    • #11092 Reply
      Anonymous
      Inactive

      Car will start but quits after 3 seconds.

      • #13928 Reply
        Protech
        Guest

        Need a little more information here! Is the security light on or flashing? Check engine light? Does it do the same thing every time? When did the problem start? Any work done prior to the problem happening?

    • #13914 Reply
      Protech
      Guest

      You need to find out what is missing when it will not run. Just guessing at parts will get expensive, as you now know. Are you loosing spark, fuel pressure, fuel injector pulse, etc. If you do not have the tools to check these things, you may have to take it to a mechanic. Right off the top- an oxygen sensor will not cause your Pontiac to stall and not start. You may have a bad CRANK sensor. They are known for failing when hot, but that is just a guess without knowing the things mentioned above.

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