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Erratic Revs on Start Up

metricspaces Aug 14, 2010

  1. Broken Byzan

    Broken Byzan Photographic Moderator Staff Member Moderator VCDS Map User quattro Audi A4

    I thought the revs were supposed to rise when the SAI is on to aid heating the CAT.

    I look forward to the outcome from Audi
  2. metricspaces

    metricspaces Member

    This isn't normal. Otherwise my car would always have been doing it - it only started doing it recently, it doesn't always do it on a cold start either (regardless of how hot\cold it is outside).
  3. drfeelgood

    drfeelgood Member

    Well i took it to audi, and they couldent find anything, in typical fashion "oh the computer is not showing any issues" ******* computer, christ do all these guys do is plug a computer in and itch there **** for an hour looking at graphs? They got a bit surprised when i told them it could be a vac leak past the maf, so the computer might not register there being a problem,
    at least they re-alligned my drivers door so it dosent keep catching the lock, free of charge, but yep typical useless audi, will take it to a specialist when i can be bothered.
    Last edited: Sep 1, 2010
  4. JD09

    JD09 I'm not modding, I'm improving VCDS Map User

    You mentioned this to me a while ago buddy, when I mentioned my idle when warm and cold is a little uneven. Think you said it was a specific system, like the n247 or something, that regulates cold air on start up?
  5. Welly

    Welly VX220 SC Driver :)

    That was the SAI system - the secondary air injection system but only the APY has it. Also, the N112 valve regulates that on the APY engines.

    All the S3 variants have the N249 valve assembly, which is that mess on top of the rocker cover. Notorious for leaking as there are so many joins.

    It's normally an inlet manifold vac hose.

    Easiest way to find out is to reset fuel trims by clearing fault codes, and then monitor short term fuel trims in block 032 in VAG COM. If the number clicks up - hello vac leak.
  6. JD09

    JD09 I'm not modding, I'm improving VCDS Map User


    That's like me talking to you about CTRs, ORs and the percentages to go with them, i.e. means **** all to me lad ;)

    Might have to bob down your way when I get bored over a weekend. Get you to show me the yellow bus and the wonders of using this software and lead I have sat here!!
  7. Welly

    Welly VX220 SC Driver :)

    Always welcome dude!

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