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2004 Pontiac Grand Prix Question: rpms go up and down when idleing

 

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laguna13, 3.8L V6 Supercharged, Tempe, AZ, March 22, 2009, 14:17
 Rookie

cars rpms go up and down when idleing. car has new cats and o2 sensors and check engine light is not showing anything is wrong?

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  • Answer #1

    Russ March 25, 2009, 20:49
     Master

    The cause of an idle surge can sometimes be hard to pinpoint. A sensor could be failing but not enough to turn the check engine light on. You may have a dirty throttle body or a fuel injector issue. This problem may need to be checked out by a qualified technician. If you don't have a regular shop that does your repairs check out the listings at www.repairpal.com.

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  • Medium-star Best Answer
    Visitor, May 17, 2010, 08:32

    I had the same problem with my car start about 2 months ago and thought it was the O2 sensor as well, but it turns out it was the mass flow air sensor instead.

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