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Now What!!!??? bloody mis-fire

Discussion in 'A4/S4 forum(B5 Chassis)' started by jcb, Mar 28, 2012.

  1. jcb

    jcb Active Member
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    pulled out of a junction rather exuberantly and about 20 yds down the road engine died!
    started up with misfire on 2 cylinders (not this again I thought, thinking of the broken MAF situation i had that cost me 6 hrs on tha A1!)

    pulled away and as revs rose 4 cyl kicked in.
    doesnt like high load/rev combos and drops a cylinder

    need to VAG it today but not looking forward that!
     
  2. Bradderz_1988

    Bradderz_1988 Dont replace it, Upgrade it !!

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    Try popping the connectors of the coils 1 by 1 see if drops a cylinder or stays the same.
     
  3. Broken Byzan

    Broken Byzan Photographic Moderator
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    ICM would be a guess, only thing that is connected to more than one cylinder assuming mechanicals check out
     
  4. jcb

    jcb Active Member
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    ICM?
     
  5. aragorn

    aragorn "Stick a V8 in it!"
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    ignition control module.

    Its on top of the air box.
     
  6. jcb

    jcb Active Member
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    yes I see, googled it.

    only done an engine code search and it was clear
    am about to do a full search when I can find the laptop charge cable
     
  7. Broken Byzan

    Broken Byzan Photographic Moderator
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    It rarely throws a code on the std engine management sadly.
     
  8. Bradderz_1988

    Bradderz_1988 Dont replace it, Upgrade it !!

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    Mine didnt when it dropped a coil just popped and swapped to find the bugger lol
     
  9. jcb

    jcb Active Member
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    useless system that can stall the engine and run on half the engine and the ECU thinks its normal!
     
  10. Foxmeister

    Foxmeister Fired Up!

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    Slightly off topic, but why did you choose your username JCB? Keen interest or operator as a job???
     
  11. jcb

    jcb Active Member
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    ha, its a long story!
    I needed a psuedonym for a job I had 15 years ago (think of "James" in the Bangladesh call centre but different!) so I stole the name of a guy I went to school with, initials JC.
    Didnt want to look like I was the second coming of Jesus so I put the B after it!
     
  12. Foxmeister

    Foxmeister Fired Up!

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    Ah right, good idea!

    Thought there was an up and coming yellow respray maybe with the addition of custom rear stabilisers for the Audi! lol

    Would love a shot of a 3CX thou!
     
  13. jcb

    jcb Active Member
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    so it is dropping a cylinder under load or highish revs
    few hundred yards later of driving like miss daisy and it comes back on all four.

    if I can get it up to speed with medium revs and under light load it will come back on all four cyls


    is there a block I can monitor or log with VAGCom to see what the ignition is doing before I start replacing ignition components willy nilly?

    does this sound like an ICM?
    do I buy new? (again)!
     
  14. aragorn

    aragorn "Stick a V8 in it!"
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    Doesnt really sound like an ICM, they usually just die and the cylinder simply never fires.

    I presume you've checked all the spark plugs first off?

    If so then get yourself a known good coil and swap them out one by one until you find the culprit.

    If swapping coils round doesnt fix it, then try another ICM.
     
  15. jcb

    jcb Active Member
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    plugs are brand new, coils were checked when the MAF died 2 months ago, could check them again I suppose but the problem is it only ever misfires when giving it large at high revs or high load

    soon as you pull over it stops!

    anyone got an ICM they want to load (possibly sell!) to test that theory?
     
  16. aragorn

    aragorn "Stick a V8 in it!"
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    Brand new since the issue started? Or just changed recently?

    I think i have a spare ICM, will have a look in the garage.
     
  17. jcb

    jcb Active Member
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    8 weeks.
    have a new set that I may try
    could really do without shelling out for new coil packs and ICM's

    will swap plugs out and check some coil packs to see if I can pin it down

    cheers
     
  18. aragorn

    aragorn "Stick a V8 in it!"
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    Even if you just take the plugs out and check them, rules out the possibility that ones fallen apart or something!
     
  19. murran

    murran Active Member

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    wonder if this is oil pressure related?
    as in the relief valve is stuck shut? so when you boot it up to high revs the oil pressure is passing the 70 odd psi the relief valve should limit it too.
    the high pressure jacking the lifters up causing the valves to not be able to shut completely?

    does it do it worse/more from cold/warm than it does when hot?
     
  20. jcb

    jcb Active Member
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    cant say I have noticed a link.
    would say that most times it has happened the car has been running more than 5 mins, but short journeys so may not be fully up to temp in this inclement weather.

    will pull plugs and mess around with coils

    cheers
     

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