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

Over boosting

Discussion in 'A3/S3 Forum (8L Chassis)' started by JLA, Dec 18, 2008.

  1. JLA
    Offline

    JLA Member

    Joined:
    May 23, 2007
    Messages:
    101
    Likes Received:
    0
    [Dec 18, 2008]
    We have a 110bhp tdi and it suffers from the over boost problem, I had it checked by a garage and they said it could be a number of things, of which all have been covered on here too.

    My theory is, if there was a fault with the turbo would it not cut out every time it reaches a certain pressure or drive at a certain amount of revs etc? Instead it seems to do it randomly, sometimes it won't do it for a day or two and other times it does it every time you put your foot down.

    Also I noticed it feels like its hessitating/a little flat sometimes, even at low speed which makes me wonder whether it could actually be a sensor or something that controls the turbo?

    I've changed the vac pipe from the actuator and that hasn't helped. Could anyone tell me what else to check/try before I start looking for a new turbo.

    Thanks.
    #1
  2. Ads

    Ads

    [Sep 16, 2014]

  3. h100vw
    Offline

    h100vw Member

    Joined:
    Aug 6, 2006
    Messages:
    218
    Likes Received:
    1
    [Dec 18, 2008]
    Is the actuator stuck/sticking closed? A scan with VAG-COM would most likely throw up a culprit

    Gavin
    #2
  4. domburg
    Offline

    domburg Member

    Joined:
    Mar 19, 2008
    Messages:
    89
    Likes Received:
    0
    [Dec 18, 2008]
    had this too on my olf golf gt tdi, in turns out the actuator was seized, however it may be just the MAF, run VAG COM on it as stated above
    #3
  5. JLA
    Offline

    JLA Member

    Joined:
    May 23, 2007
    Messages:
    101
    Likes Received:
    0
    [Dec 18, 2008]
    I had a look at it last night and tried to move the actuator by hand, is it meant to be hard to move or fairly resistance free? Also, does the rod push or pull against it. I'm guessing it pulls seeing as it has a vac pipe? With this said, if its meant to be fairly resitance free then I think there is a problem with it because I could hardly move it.

    domburg, how did you sort yours out, Audi said they can't get just the actuator, is it repairable? Also, what is a MAF? I don't know anyone with a vagcom or get chance to take it anywhere that could do it for me.
    #4
  6. domburg
    Offline

    domburg Member

    Joined:
    Mar 19, 2008
    Messages:
    89
    Likes Received:
    0
    [Dec 18, 2008]
    from what i gather, (dont quote me), i think it should be able to be moved fairly easily, a brand new turbo was put on it to cure it, however im sure you could get it re-built but it depends on cost i suppose.

    the maf is the mass air flow sensor, its part of the pipe from the air box to the throttle body

    dom
    #5
  7. h100vw
    Offline

    h100vw Member

    Joined:
    Aug 6, 2006
    Messages:
    218
    Likes Received:
    1
    [Dec 18, 2008]
    The actuator on the big turbo conversion I bought was set to 28PSI, a bit on the heavy side of a petrol car. You could move the actuator by hand no problems. I can't remember which way it went though and a diesel turbo may be different.

    It would take a while but I think you could remove the turbo or possibly the downpipe and free up the actuator.

    Gavin
    #6
  8. VRStu
    Offline

    VRStu Just Looking VCDS Map User

    Joined:
    Oct 6, 2008
    Messages:
    1,073
    Likes Received:
    3
    [Dec 18, 2008]
    Sticking VNT vanes is quite common. It does normally occur when you give it a bootfull.
    #7
  9. h100vw
    Offline

    h100vw Member

    Joined:
    Aug 6, 2006
    Messages:
    218
    Likes Received:
    1
    [Dec 18, 2008]
    Another good call.
    #8
  10. JLA
    Offline

    JLA Member

    Joined:
    May 23, 2007
    Messages:
    101
    Likes Received:
    0
    [Dec 19, 2008]
    Thanks for all the info, but I have more on this...

    Driving along normally it does it too, not accelerating or going fast, just normal 60-70mph for no reason and also I can feel it 'hunting' a little too, both of these could be due to the sticking vanes. But, when I accelerate I can hear a shhhh noise (for want of a better explanation lol). It sounds like a blow off valve of some sort and keeps on going until I take my foot off the throttle or it goes into limp mode. Its not the noise of the turbo spooling up as I can hear that too.
    #9
  11. JLA
    Offline

    JLA Member

    Joined:
    May 23, 2007
    Messages:
    101
    Likes Received:
    0
    [Dec 19, 2008]
    Can anyone recomend an ebay vag com that comes with everything I need so I can check the fault codes myself??
    #10
  12. h100vw
    Offline

    h100vw Member

    Joined:
    Aug 6, 2006
    Messages:
    218
    Likes Received:
    1
    [Dec 19, 2008]
    I bought an ebay cable years ago and then got the real thing for the full access and ability to do CAB BUS vehicles.

    You should be good with any of them really, just be aware that it often takes some messing about to get them going the first time. USB drivers are the usual snag.

    I wonder if there's 2 problems, something sticking causing high boost and it is then escaping from somewhere? Which is what you can hear.

    I think that taking it to a VW specialist would be worth the trip.

    Gavin
    #11
  13. JLA
    Offline

    JLA Member

    Joined:
    May 23, 2007
    Messages:
    101
    Likes Received:
    0
    [Dec 20, 2008]
    I think I'll Just see if I can trade it in today. I've had no end of trouble with it in the 2 years I've had it and now I've had enough.
    #12

Share This Page