Question about 1998 Pontiac Grand Am

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98 Grand Am GT 3.1 engine Very high idle when started. Sometimes you can shut it off and restart it and it will idle fine. Also using lots of gas. Have changed TPS, Iac, and EGR valve. No vacuum leaks can be found. Only codes thrown was a Random Multiple Misfire code. Could the Mass Airflow sensor cause this, or is it more likely a ECM problem?

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  • Pontiac Master
  • 14,036 Answers

MASS AIR FLOW CAN CAUSE PROBLEMS IF ITS DIRTY OR SKEWED .YOUR IDLE AIR INLET PASSAGES OR THROTTLE BORE IS DIRTY OR FULL OF DEPOSITS.BESURE REPLACE EGR VALVE GASKET THE OLD GASKET WILL LEAK.CHECK FOR THROTTLE PLATE THROTTLE SHAFT OR LINKAGE IS DAMAGED OR STICKING.

Posted on Dec 30, 2010

Testimonial: "THANKS. Going to pull it in the shop this weekend and not leaving until I figure it out or blow it up! LOL"

  • Jason Hayes
    Jason Hayes Jan 02, 2011

    Yep, a different Mass Airflow Sensor seems to have been the key. Still have a few little gigs, like a kind of rough idle, but we'll get to that tomorrow.

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