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  1. #1

    Default Alt. failed, now lose idle - HELP!

    Well I started with just a bad voltage regulator in the Alternator it was on ( charging) then off. My wife drove it two short distances in one day the second of which the car would not start. The alternator showed a bad regulator in the alternator so I replaced the alternator with a new one. Charging is back. Now I have the problem of a low idle, so low when turn into a parking spot or driveway and the AC on it dies. Changed the plugs and wires today, its a little better but still dies.

    It is a 2003 Sub and has 187000 miles. Runs great, does not burn any oil. Anybody got any ideas?

  2. #2
    Sr. Engineer
    Join Date
    May 2009
    Manitowoc, WI


    Have you checked the battery? Your bad alternator plus totally discharging it might have wrecked some of the cells in it..

  3. #3


    I haven't checked the battery but I will. It seems to start fine so I assumed it was good. A GM guy thinks the Throttle body needs a good cleaning by removing the thing and making sure 187000 miles hasn't gotten it dirtied up. So that's on for tonight. The idlle valve may be stciking a little, we'll see and let you know.
    Last edited by 06GTOM6; 01-06-2010 at 07:50 AM.

  4. #4


    Well the throttle body was the problem. Don't ask me why. I pulled it of and totally cleaned it with cleaner, put it back on andthe problem cleared. There was a ridge of soot built up aroun the edge of the throttle flapper which mad a big influence at idle.

    Guess what? My transmission started shifting smoother and also the HVAC seems to work better.

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