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1.8T AGU Fubar?

Discussion in 'A3/S3 Forum (8L Chassis)' started by Jboy, Mar 17, 2013.

  1. Jboy
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    Jboy New Member

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    Evening folks,

    I'm having problems with my 1997 1.8T AGU engine with 170k on the clock. Original thread here:
    http://www.audi-sport.net/vb/a3-s3-forum-8l-chassis/182415-1-8t-turn-over-but-not-firing.html

    The original issue seems to have spiralled into a whole world of pain.....

    Brief background: Driving along one night, done 25 miles and car started misfiring above 4k rpm then eventually cut out, failing to start again that night. Next morning got it started and drove it home, after exactly 25 miles again the misfire started, 3 miles later it cut out and wouldnt start again. Changed fuel filter and fuel pressure reg..... made no difference.

    Now, it sits in the drive, I can get it running but the throttle has to be right down. When running it sounds well enough, but will not idle what so ever. Stalling every time. Symptoms of god knows what are now:

    - 4000rpm+ stutter, splutter and misfire.
    - Will not start without throttle down
    - Will not idle

    Now, for the mind boggling part. When ignition on but engine off or after stall the following happens:

    - Fuel pump relay triggers in odd pattern (fast and slow for alternate durations) Checked relay, all is good.
    - As expected from testing relay... fuel pump doesnt recieve constant 12v, but 12v in alternate pulses.
    - Throttle twitches in same rythm as fuel pump relay. I can feel it twitching on pedal, but also see stepper motor twitching next to the throttle butterfly. Again this is in same alternate and odd rythm as fuel pump relay.
    - Throttle stepper motor emmits high pitched whine.
    - 3rd injector is constantly firing until I pull the plug off. Then the relay stops and throttle stops.

    I took it to a local garage for the dignostics test, but he couldnt get the computer to connect to ECU. Got a fella coming tomorrow to have another go... a pro apparently. Either way, I've never come accross anything like this before. Could it be a sensor fubar? Or as much as I hate to say it, the ECU wrecked?

    Any help much appreciated.
    Thanks guys,
    Jim
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  2. s33nyboy12
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    s33nyboy12 Active Member

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    You should post up where you are in the uk or check the vcds section of the forum to see if anyone near you has vagcom and can help.

    Sean
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  3. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    Water ingress into ECU or wiring would be my guess given the random ness of it
    #3
  4. btmotorsport
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    btmotorsport Soon be christmas!!!!!!!!!!

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    duff earth or dead ecu. try volt dropping the earths
    #4
  5. 16Klappe
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    16Klappe Princess Slayer

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    New ECU time, not a huge job at all. Speak to Niki at R Tech and he can defeat it, as long as it comes from the same software car it'll plug right in.
    #5

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