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  • avatar zaken1 03/17/10 12:07 am PST

    Unfortunately; there often is enough interaction between various components that the computer readouts will sometimes tell you about something which is being caused by another problem, rather than it being the root cause. You MAF sensor message sounds like just that kind of thing. The MAF is primarily measuring intake manifold vacuum. The manifold vacuum can go out of specs if the ignition timing is too far retarded (from either a bad crankshaft position sensor, or a bad camshaft position sensor; OR FROM A TIMING CHAIN HAVING SLIPPED AND JUMPED A TOOTH ON THE SPROCKET.) All of these things could throw a MAF code.

    From what you have now written; It sounds to me like the timing chain has slipped. This can be checked by running a compression test on the motor; if all of the cylinder compression readings are below the minimum allowable figures, this is a reliable indicator that the timing chain is off. In that case; the timing chain and sprockets will have to be replaced.

    If the compression is good; I would replace the crankshaft position sensor; and if that doesn't fix it; I'd replace the camshaft position sensor.

    I assume you know that on 1996 and newer vehicles; old codes do not automatically clear when a problem is repaired. They can only be cleared with a code scanner that has the capability of clearing codes.

Answers

  • zaken1 03/14/10 8:19 pm PST

    This problem is usually caused by a bad crankshaft position sensor; so I would suggest replacing that part. Occasionally, it is caused by a bad camshaft position sensor; so if replacing the crank sensor doesn't fix it, I would then replace the cam position sensor.

    If for some reason you decide to respond again about this issue, please do so by posting your response here, underneath the existing responses (You can do so even after a question has been closed). But if you respond to an existing topic by opening a new question, it will promptly be deleted; and neither you nor I will benefit from that.


  • mikey555 03/16/10 3:53 pm PST

    Thank you for the info....I will try that. I pulled the codes and the reader i have showed Mass air Flow sensor ... I replaced that and it is still doing the same thing and throwing the same code...
    is my code reader junk or would that be caused by the sensor you spoke of???

  • zaken1 03/17/10 12:07 am PST

    Unfortunately; there often is enough interaction between various components that the computer readouts will sometimes tell you about something which is being caused by another problem, rather than it being the root cause. You MAF sensor message sounds like just that kind of thing. The MAF is primarily measuring intake manifold vacuum. The manifold vacuum can go out of specs if the ignition timing is too far retarded (from either a bad crankshaft position sensor, or a bad camshaft position sensor; OR FROM A TIMING CHAIN HAVING SLIPPED AND JUMPED A TOOTH ON THE SPROCKET.) All of these things could throw a MAF code.

    From what you have now written; It sounds to me like the timing chain has slipped. This can be checked by running a compression test on the motor; if all of the cylinder compression readings are below the minimum allowable figures, this is a reliable indicator that the timing chain is off. In that case; the timing chain and sprockets will have to be replaced.

    If the compression is good; I would replace the crankshaft position sensor; and if that doesn't fix it; I'd replace the camshaft position sensor.

    I assume you know that on 1996 and newer vehicles; old codes do not automatically clear when a problem is repaired. They can only be cleared with a code scanner that has the capability of clearing codes.

  • jerryofmaplan 10/11/10 11:18 pm PST

    I dont know if our car problem is exactly the same but mine had a similar problem.

    I have a 97 Grand Prix supercharged that was doing this very thing. When I start it up, it might idle 3-8 seconds, and less time than that if I pressed the gas pedal. I first thought the fuel pump was bad and replaced it, turned out it was not that (ouch $330.00). Turned out to be a speed control resistor used for the fuel pump. My 97 has 2 relays that run the fuel pump, relay 1 is called the fuel pump relay, it pumps up the fuel line and runs for a burst of about 3 seconds when I turn on the key. The other relay is called F Pump Spd Cont, and it works in conjunction with a resistor that mounts behind the right front headlamp down low on the fender well. The delco part number for this resistor on the 97 is 88951182. The electrical current flow is limied to the fuel pump through this reisitor and it allows it to operate at a lower speed. However if the resistor burns out, the fuel pump will not run long after the first relay shuts off. This relay is only available through your GM dealer or other delco sources, and costs about $58.00 (big rip off). I suggest you check to see if your 2000 is equipted with this resistor, I know the supercharged models use it. If your car has this F Pump Spd Cont relay you will find it in the fuse box under the hood by the washer resevoir. It is relay number 15. You can bypass the resistor by removing the relay and placing a jumper (I used a paper clip) across pins 3 & 4 of the socket the relay came out of. If this makes the car run, then you need a new resistor, or the wiring got damaged.


    Source: jerryofmaplan

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