Question about 1991 Pontiac Grand Prix

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Misfiring it misfires and has no power and excessive fuel in the exhaust system, I changed the plugs and plug leads, it is a 1992 pontiac grand prix 3.1 and milage is 85k

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  • tleonard727 Sep 23, 2008

    It was one of the coils that caused the misfire, seems to be fine now.



    thank you.



    regards Tadhg

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  • 73 Answers

Well there are several things that could cause this problem...

1. one of the coils may not be firing.
2. the ignition module could be bad.
3. the mass air flow sensor could be tellign the car to run rich (too much gas)
4. if the car is equiped with a map sensor it could do the same as a mass air flow sensor.
5. fuel pressure regulator could be leaking at vacuum port drawing in more fuel than needed.
6. the computer itself could be bad as well.

The car either has a map sensor or mass air flow not both. The mass air flow would be right after the air cleaner housing usually a 4 wire connector. map sensor is normally located on the rear of the upper intake manifold with 1 vacuum line going to it with 3 wire connector. Hope this helps.

Posted on Sep 11, 2008

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