Question about 2002 Pontiac Grand Prix

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My 2002 grand prix was running rough. I plugged my code reader in and the mass air flow sensor came up. I changed that.Then the o2 sensor came up and I changed that. misfire on multiple cylinders came

Vehicle will not go over 25 mph

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Check for a restriction of some kind, fuel--air--exhaust. Use a gage and check fuel pressure. What was the actual 02 sensor code? Can you tell if the system is running rich or lean? In park, will the engine rev normally?

You don't think the tranny has an issue?

Posted on Dec 15, 2014

Testimonial: "used my gage to check fuel pressure and its at 55 lbs. The system was running lean on the left bank. In park I can only get the engine to rev between 2500 and 3000 rpm. once it hits about 3000 rpm it wants to bog down. Just had a rebuilt tranny put in about 1year 5months ago"

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  • jack layton
    jack layton Dec 15, 2014

    With the key off, does that fuel pressure hold for a bit or does it drop like a rock? With the fuel gage hooked up, engine idling, aim the gage bleeder tube into container and press the gage bleed off valve. The engine shouldn't stumble, if it goes to acting up, may be a fuel volumn problem, even though the pressure appears ok.

  • Robert Mortimore
    Robert Mortimore Dec 15, 2014

    checked it again and reset codes. fuel getting to the injectors don't seemed to bo be a problem. Took it for another ride and can get the car up to 30 mph at about 1800 rpm before the the service engine light came on. Got it back to the garage and the codes are po300 multiple cylinder misfire and po404 egr flow ckt range performance

  • jack layton
    jack layton Dec 15, 2014

    I can't tell, maybe a clogged fuel injector or vacuum leak? Is the tranny shifting?



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