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Misfire mystery ??

Discussion in 'A3/S3 Forum (8L Chassis)' started by midge, Jun 29, 2012.

  1. midge

    midge New Member

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    Hello, i recently bought an a3 with agu engine, the car has a misfire when its under load, its ok if you ease the throttle in very gently though, we put the diagnostics onit and it came back with nothing, so i presumed it must be the plugs which i have since changed for BKR6EK, however its just the same, with misfire when its under load, and nothing coming back on the diagnostics.

    When the car is idling if i unplug a coil the engine note does not change, no matter which one i unplug ?

    when i picked the car up it had a flat battery but was fine after being jump started, and has been fine every since for startingi did suspect maybe it needs a new battery, but its fine for starting the car so i cant see it being that, because the car isnt giving me any problem codes i dont really know where to start, i dont want to keep buying parts without finding the problem first!

    Is there a way to test the coils or ignition apmlifier?
     
    #1 midge, Jun 29, 2012
    Last edited: Jun 29, 2012
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  3. Sandra

    Sandra MODERATOR
    Staff Member Moderator TeamMisano Gold Supporter quattro Audi S3

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    Welcome Midge, glad you can post now. Any pics of the car? One of the guys should be along shortly with advice. Enjoy the forum. :) x
     
  4. cjsuk

    cjsuk Active Member

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    Did you use a generic diagnostic tool? or vag-com (VCDS). I'm only asking as you said the bettery was flat and it was jump started, I have read a few different cars now and on all the ones which have had a flat bettery and jumped the ECU seems to go in to some safe mode. With a generic diagnostic it reads no codes with vag com it wont connect to the controller.
    To solve this I allways disconnect the battery for an hour then re connect turn the ignition on for 5 mins turn it back off then do the diagnostic.

    I know this does not answer your question in any way, its just a thought from past experience and to try and get you a code.
     
  5. s3dave

    s3dave TFSI Hybrid
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    It could be fuel related, when was the filter last changed? have a look at the stickies for DIY injector cleaning..:icon_thumright:
     
  6. jezzy

    jezzy Member

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    i had this problem, and today new coil packs and i zip tied the harness on to the coil packs and the problem has gone.
    car would hesitate under load and vcds gave no error codes and yes i will replace the harness at some stage.
     
  7. midge

    midge New Member

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    The coil connectors dont look like its possible for them to come loose as they have metal clips that pull the connector tight, good tip on disconecting the battery for an hour then trying to read it, ill try that tommorrow (my £20 diagnostic tool wouldn't even connect, but a friends £1600 one did and came back with a couple of failed to start codes due to flat battery but didnt come back with anything else)

    I done a compression test to rule hg out and the engine is compeltely healthy at 150psi on each cylinder.

    I will do the injector cleaning over the weekend, thanks for the tip!
     

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