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Cold Start Idle problem (With Video)

Discussion in 'A3/S3 Forum (8L Chassis)' started by Westy, Feb 3, 2010.

  1. voorhees
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    voorhees Moderator Staff Member Moderator

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    [Feb 10, 2010]
    sorry the temp sensor didn't work Neil
    can you not loosen the hose and give it the TB quick clean to see any difference ?
    #41
  2. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 10, 2010]
    Don't worry about it jase, my first thought was the temp sensor anyway. I'm going to disconnect the maf for the morning just to rule that out then I'll give the tb a full clean at the weekend. I've got VCDS so I can re-align the tb too.
    #42
  3. S3BAM
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    S3BAM Member

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    [Feb 10, 2010]
    Mine does pretty much exactly the same seems worse if i dont use for a few days..most days absolutely fine.
    drop me a pm once you found out what it is ive put it down to the cold weather..!!! checked everything i can think of whilst doing my front mount..
    #43
  4. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 11, 2010]
    This mornings test was inconclusive! I disconnected the MAF and it started a lot better than normal with just one tiny litter stutter! I hope its not the MAF as I'm getting fed up of wasting my money on crappy sensors. I'll clean the TB this weekend first and hopefully that'll do it, if not I'll be back to Audi for my weekly bum raping!
    #44
  5. Welly
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    Welly VX220 SC Driver :)

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    [Feb 11, 2010]
    Cheers Westle, that's the first thing today that's made me smile!! :)

    I've got to go up there myself for a bum raping tomorrow... Yay! It's like being in prison.
    #45
  6. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 11, 2010]
    I need to change my status above to "Replacing Parts Weekly"!

    I've been to Audi so many time recently that they dont even need to lube up any more they just stick it in dry! :asskicking:
    #46
  7. Jackson_a3
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    Jackson_a3 Member

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    [Feb 11, 2010]
    Interesting to see results as mine started doing this last night. Strange thing is it began doing it after I got home and left it to idle for a minute before I switched it off, not from start up.

    Started it again a bit later and rev needle was bouncing all over the place, kept stopping itself from stalling though. Levelled out a bit after a while.

    Think it could be the same problem or something different since Westle you say yours is fine after a while?
    #47
  8. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 11, 2010]
    Mine is fine after about 20 seconds as you can see in my vies above. I'm going to realign the TB in a min then see what it does when I leave work at 5pm.
    #48
  9. S3BAM
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    S3BAM Member

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    [Feb 11, 2010]
    keep us informed mine was a knightmare cut out twice this morn before starting fine. defianetly weather related as its fine whens its warmer...
    #49
  10. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 11, 2010]
    I just did a TB realignment in the carpark. Values were as follows:

    Before:

    Duty Cycle1 14.5%
    Duty Cycle2 84.8%
    Count 8

    After:

    Duty Cycle1 11.3%
    Duty Cycle2 87.9%
    Count 8

    I have no idea what any of this means but it shows a difference!!! I'll start the b!tch up when I go home at 17:00 and see what happens. I'll post up the results at about 17:30
    #50
  11. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 11, 2010]
    Ok I'm now quite sure that the problem is with the TB. I started it up at 17:00 when I left work and for the first time ever it stalled! I'll see if it sorts itself out for the morning startup, if not I'll get some carb cleaner on my way home tomorrow and clean the TB on Saturday.
    #51
  12. paulious
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    paulious Member

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    [Feb 13, 2010]
    Hi this maybe no use to you as your engine is alot different but on my 99 a3 1.6 i had exactly the same problem. Also just after starting and pulling off my drive going into second gear i'd get to the junction at the end of the road put the clutch in as i'm slowing down and the idle revs would bounce all over the place and nearly stall. After a couple of minutes warmed up the problem would go away. However i did fix the problem. Due to a hasty oil change i poured oil too quickly and it overflowed into the breather valve that is next to the oil filler cap so had to strip all the air inlet and clean it but particularly i noticed inside the oil filler hole is a piece of plastic that moves around! After fiddling about moving it and cleaning the problem went away. Now starts up fine and when pressing the clutch in at the end of my road the revs go up slightly and sit at choke on idle. I'm no mechanic i just dabble but it's something you maybe able to look at and at no cost :)
    #52
  13. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 15, 2010]
    Ok I did the TB clean and realign and its still exactly the same. I haven't tried the "moving the plastic" trick mentioned above but I'm now after some more ideas.

    What could be causing this? Would a split pipe do this, because it goes away after about 20 seconds of rev hunting? :think:
    #53
  14. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 16, 2010]
    Anyone got any more ideas or similar experiences?
    #54
  15. Welly
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    Welly VX220 SC Driver :)

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    [Feb 16, 2010]
    Hmmm, I'd say a split pipe was unlikely really. If a pipe was split then you would expect it to do it all the time at idle.

    Common hose for splitting is the PCV hose underneath the inlet manifold, common as muck for going.

    It could be a hose I guess. The ECU fuels for what it expects the air to be on start, and then after a few seconds reads through lambda that something is incorrect and adjusts accordingly to bring you to a happy place.

    Odd how it's only on cold start though, that's what throws me....
    #55
  16. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Feb 16, 2010]
    I replaced the fuel regulator hose under the mani last month so it's not that. I'm just completely stumped! I only need to keep my foot on the gas to steady the revs for about 10 seconds then the problem goes! :think:
    #56

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