1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Rising and falling rev counter needle on idle

northern monkey Nov 24, 2010

  1. northern monkey

    northern monkey Member

    40
    0
    6
    Had my S3 for a few months now and since I bought the car the rev counter needle rises and falls by about 50rpm while idling.
    I have had Audi look at it and they diagnosed the induction system needed cleaning. I had it cleaned and it seemed to make a little difference at first but now is the same as it was. There is a new air filter fitted aswell.
    Without keep going back to Audi to charged a fortune to fix nothing. Is there anyone out there that can help diagnose what the issue might be?

    Graeme
     
  2. bengal

    bengal Member

    537
    1
    16
    Try unplugging the maf and if it stops then its probably the maf at fault. Could also be a vac leak but try the maf first.
     
  3. northern monkey

    northern monkey Member

    40
    0
    6
    Sorry to be dim.
    What is the MAF? I had thought about a vac leak but thought Audi would've checked for that first.
     
  4. bengal

    bengal Member

    537
    1
    16
    Between the airbox and intake pipe there is a plastic cylindrical part with an electrical plug thats the maf so you need to unplug it and run it unplugged to see if it cures it. As for audi imo some of them are not all there cracked up to be so its very possible for them to miss simple things like a vac leak the same applies for general garages as well you would be much better off with an audi specialist.
     
  5. bengal

    bengal Member

    537
    1
    16
    Or a good tuning garage.
     
  6. JD09

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

    3,096
    46
    48
    Think this could also be temp sender related? From what Welly said, unless I've misunderstood, the temp sender or thermostat itself might be faulty...
     
  7. NoggyS3

    NoggyS3 Member

    242
    1
    16
    Really...?
     
  8. Alex C

    Alex C Well-Known Member VCDS Map User Audi S3

    3,294
    372
    83
    mmm, have you replied in the wrong thread?
     
  9. Welly

    Welly VX220 SC Driver :)

    10,696
    129
    38
    I could have sworn I replied to this thread already - but apparently I didn't.... weird....

    The symptoms you describe are the symptoms I would expect to see from a simple vac leak. Hunting at idle is normally a vac leak off the manifold, or a leak elsewhere in the charge system.

    Don't expect Audi to be able to diagnose everything. IMO they are simply the same monkeys you get down your local garage in fancy uniforms, called 'technicians'.

    Start with a good old vac leak hunt, check all the pipes off the lower side of the manifold. Personally, I'd buy some cheap silicone hose from ebay, in various sizes (3mm, 4mm and 5mm) and simply replace all that you can. At least this way you KNOW it's not a vac leak.

    Also check for splits in the DV hose, and the pipes around the EVAP canister (the clicky thing that sits by the header tank).

    As JD said, the CTS can have some odd effects on the cars when they go, BUT, it's normally related to starting the engine when it's warm, so I wouldn't suspect that here.
     
  10. JD09

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

    3,096
    46
    48
  11. Alex C

    Alex C Well-Known Member VCDS Map User Audi S3

    3,294
    372
    83
    :)
     
  12. JD09

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

    3,096
    46
    48
    Shush you, it's been a long day* ;)







    *Read year
     
  13. northern monkey

    northern monkey Member

    40
    0
    6
    Thanks guys.
    So homework for tonight. I have work out:
    1. What the CTS is and what it looks like?
    2. What the EVAP canister is and what it looks like?
    3. Which are the DV hoses?
    I hope I don't sound ungreatful. I'm merely highlighting I know near to nothing.

    G
     
  14. Madeley

    Madeley Member VCDS Map User

    125
    0
    16
    Have you had the throttle body cleaned? a dirty one can cause these symptoms.
     
  15. finesse

    finesse Active Member

    2,805
    11
    38

    on asn I answer fits all

    boost, vac leak turbo gone blaa blaa
     
  16. northern monkey

    northern monkey Member

    40
    0
    6
    Yip. I had the throttle body cleaned by Audi, Which hasn't changed a thing.
    How difficult is it to change the said hoses? Does anyone have any recommendations on good quality, but not expensive hoses? Ideally not bright blue Samco ones.

    Graeme
     
  17. Welly

    Welly VX220 SC Driver :)

    10,696
    129
    38

Share This Page