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S3 MISSFIRE

gurry May 28, 2007

  1. gurry

    gurry New Member

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    HI CAN ANYBODY HELP!!?? I SEEM TO HAVE A MISSFIRE, WHEN REVING THE CAR AS THE RPM REACHES 4,000 RPM THER SEEMS TO BE A MISSFIRE ON ONE OF THE CYLINDERS FOR APX 1,000 RPM, I HAVE HAD THE CAR PLUGED INTO VAG COMPUTER BUT IT DID NOT SHOW ANY FAULT CODES?? ANY ADVICE WOULD BE GREAT!
     
  2. Tastyterrier

    Tastyterrier Monkey Trainer

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    Faulty Coil Pack?
     
  3. gurry

    gurry New Member

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    Im not sure, shouldn't have that shown up on the vag computer??
     
  4. Tastyterrier

    Tastyterrier Monkey Trainer

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    I aint no expert, but I know that with a faulty MAF, an error isn't always recorded, possibly the same with a coil pack.

    I'm sure someone a lot more knowledgable than me will be along soon!
     
  5. jojo

    jojo Looking for Boost! Staff Member Moderator Team Daytona Audi S3 quattro Audi A6 Audi Avant Owner Group

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    Are you 100% sure it's a missfire? If it's a coilpack problem, it should come up on vagcom, and should bethere throughout the revrange, knackered MAF would feel like a missfire, but it's more an uneven power delivery throughout the rev range.
     
  6. loftgroover

    loftgroover Member

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    The ECU will not always flag a misfire. It needs to be very serious to bring the Engine light on.

    if you log engine groups 015 and 016 on VAGCOM you will see individual cylinder misfires, if you drive up the road and repeat the conditions the misfire occurs, you should be able to tell which cylinder is the problem.

    Swap the coil ( but not plug) with another cylinder, repeat the test, if the fault moves you know its the coil. If the fault stays with the original cylinder repeat with the spark plug only, this should tell you if its plug. If it doesnyt move you then need to repeat with both coil and plug moved. If the misfire stays in the original cylinder when you have moved both coil and plug you need to look at MAF.

    Log engine 02 and this should give mass reading. a chipped S3 should consume 190+/- 10 g/s around 5600RPM. If you are much less than this then MAF could be at fault.

    Not sure MAF readings for Std S3, have a search and you chould find the values.

    HTH.
     
  7. loftgroover

    loftgroover Member

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    4000rpm is near peak torque which is higher cylinder pressure which is higher voltage demand which means more likely coil or plug.
     
  8. emzino

    emzino Active Member

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    Maybe just bad petrol? Something redex might fix...
     
  9. Jonesy

    Jonesy Member

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    Missfire's are normally from dead coils or sparkplugs but both would show on the vagcom. Try cleaning the maf and throttle body and reset the ecu, see if that helps.
     
  10. ANDYTQ

    ANDYTQ Well-Known Member

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    I have had a intermittant misfire for months,no codes showing ,i changed coilpacks,plugs no joy,it got worse and vagcom showed a intermittant lamda fault,changed it yesterday and the car is now fine again?It was misfiring in midrange ,normal slow speeds all ok ,as soon as it hit 3500-4000 it was popping and backfiring?I shall see if it stays ok and keep you posted.Cheers Andy
     
  11. simch

    simch Active Member

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    Whip out the spark plugs, agree again on it being near peak torque, could be a plug melt through oinking or detonation if you run higher boost and had some bad fuel in it.

    If there is a plug melted, find out what did it!!
     
  12. ANDYTQ

    ANDYTQ Well-Known Member

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    It started misfiring again checked plug gaps ,they were too big,regapped them and misfire is gone.Result
     

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