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Misfire on Cylinder 1

Discussion in 'A3/S3 Forum (8L Chassis)' started by Fandango80, Apr 26, 2010.

  1. Fandango80
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    Fandango80 Member

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    [Apr 26, 2010]
    Hi All!

    got a really bad misfire on cylinder 1.

    The garage cant find the problem and thought you might have heard of this... they have run a scan on the ecu (dont think it is vag com) and it says closed circuit on injector 1. They have swapped injectors over with no difference. They took the rail off and all injectors are working. Compression on cylinder 1 is down from 140 to 90 psi. my guess is that there is a fault between the ecu and the injector maybe causing it to initially run lean and over time buring the valve seats to reduce compression. Now it does not fire on cylinder 1 at all and stinks of fuel if you drive it. All sparks are strong and coil packs checked.

    Any suggestions would be really welcome.

    Cheers.
    #1
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  3. s3dave
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    s3dave TFSI Hybrid

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    [Apr 26, 2010]
    it is known to have bad wires in the injector loom, maybe worth checking? as they go brittle with the heat
    #2
  4. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator VCDS Map User

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    [Apr 26, 2010]
    so the rest of the cylinders are 140 and no 1 is 90? That right?

    It's more than likely mechanical rather than electrical by the sounds, dodgy valve or seat, bent con ron,damaged rings ,ad infinitum
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  5. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Apr 26, 2010]
    What Mark said... bent con rod is my bet tbh....

    Anything happen leading up to issue? were you driving at the time and the misfire came up?

    <tuffty/>
    #4
  6. Fandango80
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    Fandango80 Member

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    [Apr 27, 2010]
    Thanks for the input guys,

    Basically, it was proving troublesome to start a week or so before but the fuel was low and once it was filled up and a squirt of redex it was fine. There was more of a hiss sound coming from under the bonnet- sounded like a slightly blowing mainifold but garage says this is ok.

    Hmm, thinking about it, could a leaking inlet valve cause this- blowing exhaust gasses into the inlet manifold? However, I dont see how a bent conrod or leaking valve would bring up a fault code highlighting the injector electronics? Or maybe this does make sence?

    Thanks,
    Dave.
    #5

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