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IDLE SPEED TROUBLE---hunts to find correct tick over speed

quattro25years Apr 25, 2009

  1. quattro25years

    quattro25years Member

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    hi all

    i have a a6 2.8 quattro.

    whenever i stop at a junction for example, sometimes the engine cuts out or has to hunt for the correct tickover speed (this happens about 7 times out of 10).

    (once engine has cut out -- start up again and its ok),

    the problem above only seems to happen once i have driven the vehicle(any distance).

    if i just start the engine from cold , the tick over speed is perfect)

    any ideas ??

    cheers

    quattro25years.
     
  2. DGSdale

    DGSdale Member

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  3. matt_o121

    matt_o121 2.8Q

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    if cleaning the throttle body doesn't work - ( a good starting point)

    you could try the charcoal canister - i had problems with the vent to atmosphere being blocked - it comes out under the floor by the drivers door - a black pipe that goes in to the driver wheel arch.

    or the evap control valve - on top of the air filter under the plastic trim. there is a plug going to the valve - if you disconnect it the engine will run still - see if it makes any difference - doesnt put a dash light on but will log a fault in the memory.

    mine was sticking and when hot stayed open allowing un metered air in to the inlet causing hunting and low rpm at idle
     
  4. auroan

    auroan Active Member

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    Idle control valve i'll put money one it !

    Sits at the back of the engine block below the throttle body.
     
  5. matt_o121

    matt_o121 2.8Q

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    guess it depends how old the 2.8 is - 12v have idle control valves
    30v dont
     

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