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  1. #1
    AGU-TURBO's Avatar
    Audi a3 1.8t AGU

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    Random misfire a3 1.8t agu

    got my head the other day off mush and eveyrthing is running sweet apart from a random misfire, started up yesteeday morning and tryed to set off and started misfiring and cut out, started it back up and came home and eventualy stopped misfiring. switched it off and made sure all pipes were connected properly and leads to coil packs were connected properly. everything seemed fine and took it round block and was spot on, so desciede to take it for a good run and did 60 mile with not hitch apart from it not boosting properly, normaly boosts to 1 bar and is only boosting to 0.7-0.8. anyway got up this morning and did about 7 mile and was coming to end of dual carriage way and started missing again then cleared again as i was going round the round about then did it a further 4 times till i got home (4 mile)

    anybody got any sugestions, i have changed the spark plugs tonight for some denso one's and still does it, have disconected n75 which oviously drops it to actuator preasure which seems to be about 0.4 - 0.5 bar so i no that is doing somthing lol, i have also pluged into vag-com and doesn't bring any faults up at all, i would of thought that if one of my coil packs were down it would throw a fault code what do you think?

    RANDOM MISFIRING

    LOW BOOST NORM 1 BAR NOW 0.7 - 0.8 BAR

    any help would be most appreciated, thanks

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  3. #2
    <tuffty/>'s Avatar
    Badger 5 Edition

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    Log for misfires in vag com (http://www.ross-tech.com/vag-com/m_blocks/ specifically blocks 015 and 016 IIRC) oh and bin the Denso's for NGK's... Denso's are engine wreckers...

    <tuffty/>
    Silver 2001 AMK S3. Silver alcantara interior... now with added powarrrrrrrr, torques. VAGCOM + KII-USB. >> My build thread...

  4. #3
    AGU-TURBO's Avatar
    Audi a3 1.8t AGU

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    Quote Originally Posted by GT30AudiS3 View Post
    Log for misfires in vag com (http://www.ross-tech.com/vag-com/m_blocks/ specifically blocks 015 and 016 IIRC) oh and bin the Denso's for NGK's... Denso's are engine wreckers...

    <tuffty/>
    Thanks i will look into that
    the plugs that i had in were bosch super 4's and the car was misfiring about every 5 seconds on idle, put my old denso's in and this stopped.

  5. #4
    AGU-TURBO's Avatar
    Audi a3 1.8t AGU

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    If 1 of the coil packs were a bit dodgy shouldn't it throw a fault code up?

  6. #5
    <tuffty/>'s Avatar
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    Quote Originally Posted by AGU-TURBO View Post
    If 1 of the coil packs were a bit dodgy shouldn't it throw a fault code up?
    Not that I am aware of, misfires will show but no actual fault code that I know of...

    AGU has the ignition amplifier doesn't it? it could be faulty... I have no personal experience of these but there are a few threads describing similar issues IIRC... the ignition amplifier is normally bolted onto the air box..

    <tuffty/>
    Silver 2001 AMK S3. Silver alcantara interior... now with added powarrrrrrrr, torques. VAGCOM + KII-USB. >> My build thread...

  7. #6
    AGU-TURBO's Avatar
    Audi a3 1.8t AGU

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    Quote Originally Posted by GT30AudiS3 View Post
    Not that I am aware of, misfires will show but no actual fault code that I know of...

    AGU has the ignition amplifier doesn't it? it could be faulty... I have no personal experience of these but there are a few threads describing similar issues IIRC... the ignition amplifier is normally bolted onto the air box..

    <tuffty/>
    Thanks tuffty yeh it has a ign amp, im pretty sure if that would fale it would misfire on all 4 cylinders's, but could be wrong. i will keep investigating, any ideas on the low boost

  8. #7
    Prawn's Avatar
    My other car is a MINI!!!!

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    The ignition amp going won't cause all 4 to miss for some reason, mine didn't!

    Bin the densis big time though, I had the same issues, replaced my old densos for new ones and it did it didn't solve it. Spent a fortune on other bits because i ignored everyone who told me it was plugs, and in the end, it WAS the evil densos. Never using them again!
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    Prawns TFSI Turbo'd 1.8T Track Car

    But I know nothing so ignore me.

  9. #8
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    Audi a3 1.8t AGU

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    Quote Originally Posted by Prawn View Post
    The ignition amp going won't cause all 4 to miss for some reason, mine didn't!

    Bin the densis big time though, I had the same issues, replaced my old densos for new ones and it did it didn't solve it. Spent a fortune on other bits because i ignored everyone who told me it was plugs, and in the end, it WAS the evil densos. Never using them again!
    Hi prawn how was the car behaving when you'r ign amp failed. Was it randomly misfiring? Yeh ive binned the denso's and put my Bosch 4's in.

  10. #9
    s3dave's Avatar
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    Yep ignition amp...

  11. #10
    Prawn's Avatar
    My other car is a MINI!!!!

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    Just really random, sometimes it'd misfire, so sometimes it'd be fine, often started to fail when hot, and usually fixed itself for a while.

    Now run standard NGK plugs and they're great
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    Prawns TFSI Turbo'd 1.8T Track Car

    But I know nothing so ignore me.

  12. #11
    AGU-TURBO's Avatar
    Audi a3 1.8t AGU

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    if the ign amp had a fault would it throw a fault code. How much are they?

  13. #12
    Welly's Avatar
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    Quote Originally Posted by AGU-TURBO View Post
    if the ign amp had a fault would it throw a fault code. How much are they?
    Won't normally throw a code, no. I can't remember the exact amount.

    It is actually called the Power Output Stage module N122. Part numbers are 8D0 905 351 or 4D0 905 351.
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  14. #13
    Welly's Avatar
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    This may be useful for you. For an A4, however the N122 is the same so testing procedure will be identical.

    A4.B5.DIY.Ignition.DIYTestPOS - QuattroWorld Wiki
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    "Marriage is like a coffin and each kid is another nail."
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    Wellyboots, you are quite literally my most favourite pikey in the entire world




  15. #14
    AGU-TURBO's Avatar
    Audi a3 1.8t AGU

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    Thanks welly, ive just been out to check to make sure everything is connected properly and i noticed that the pipe that comes from actuator has a t-piece and splits off to tb and charcoal canister well..... i put them back the wrong way round - what a dum ass mistake. i put the pipe with the 1 way valve to charcoal canister and the other to tb lol . So oviosly the charcoal canister couldnt vent fumes back to tb but tb would of kept preasurising the charcoal canister and - fuel line i think, but i was wondering if this could be somthing to do with any of the problems if been having?

  16. #15
    AGU-TURBO's Avatar
    Audi a3 1.8t AGU

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    anyone?

  17. #16
    AGU-TURBO's Avatar
    Audi a3 1.8t AGU

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    Sorry the pipe comes from tip (not actuator lol) to tb & charcoal canister

  18. #17
    AGU-TURBO's Avatar
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    Sorry the pipe comes from tip (not actuator lol) to tb & charcoal canister

  19. #18
    Welly's Avatar
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    Quote Originally Posted by AGU-TURBO View Post
    Sorry the pipe comes from tip (not actuator lol) to tb & charcoal canister
    Hmmmm, not sure what the effect of that would be, but I can't see it causing misfires. That's not to say it wouldn't though...
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    Quote Originally Posted by Prawn View Post
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  20. #19
    AGU-TURBO's Avatar
    Audi a3 1.8t AGU

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    ok, i presume i carn't log boost with vag-com be been that i don't have a map sensor with it being agu, anyone confirm this, thanks

  21. #20
    Welly's Avatar
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    Quote Originally Posted by AGU-TURBO View Post
    ok, i presume i carn't log boost with vag-com be been that i don't have a map sensor with it being agu, anyone confirm this, thanks
    Confirmed.

    Fit a boost gauge.
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    Wellyboots, you are quite literally my most favourite pikey in the entire world




  22. #21
    AGU-TURBO's Avatar
    Audi a3 1.8t AGU

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    Yeh ive got a boost gauge and it used to boost to 1bar but only reaches 0.7-.08 bar now. i just wanted to see what requested boost was vs actual. but thanks confirming that. cheers welly

  23. #22
    Welly's Avatar
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    Quote Originally Posted by AGU-TURBO View Post
    Yeh ive got a boost gauge and it used to boost to 1bar but only reaches 0.7-.08 bar now. i just wanted to see what requested boost was vs actual. but thanks confirming that. cheers welly
    No probs. I remember what a pain that was when I had my AGU in an A3. No block 115. No block 118.

    The key to the AGU engine is the MAF. EVERYTHING is calculated from the MAF, it tells the ECU 99% of what it needs to know.

    Everything on the AGU is worked out via airflow. The ECU does know what boost there is as it has an algorithm to calculate boost from air flow vs TB angle.

    Any problems with an AGU engine, check the MAF! lol
    ------------------------------------------------------------------------------------------
    "Marriage is like a coffin and each kid is another nail."
    Homer Simpson

    Quote Originally Posted by Prawn View Post
    Wellyboots, you are quite literally my most favourite pikey in the entire world




 

 

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