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boost issues

paulrom Jan 23, 2009

  1. paulrom

    paulrom New Member

    hi all i have a b5 s4 avant on a 1999 in ming blue and i think i have issues with regard to boost

    sometimes it boosts to just 7psi and other times it goes to 10-12psi
    i know the exact boost as there is a boost gauge fitted to the car

    any idea's or is it ment to do that (i hope not as i like the 10-12 psi)there's no regularity to this ??????????

    anyone know what the standard boost should be ??????????
  2. aragorn

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

    these engines have a very complicated maze of pipework for vacuum and boost control, and they are prone to getting parts of the pipework etc split, and cause boost leaks.

    I would imagine the standard boost would be about 8psi so your spikes to 10/12 are clearly a sign of something amiss.

    I'd look at getting a health check done at MRC or Unit20, or you can perhaps check over all the pipework yourself or pressure test it, if you have the know how...
  3. stapo69

    stapo69 All hail the mighty quattro!

    Health check it, or get vagcom plugged into it see if you're getting any charge pressure control faults. Prob a small boost leak somewhere, check your hoses, see if any hose clips have dug in and cut through, throttle body boot is a common fail point. Something could be opening up somewhere but not all the time, standard boost should be around 7-8psi, remapped would be closer to 14-15psi.
  4. Siena

    Siena Active Member

    A faulty MAF will also give rise to sporadic performance / boost issues.
  5. Digger01

    Digger01 New Member

    hi i have a problem with a A4 2.0t this trouble code po299 tubo charger boost sensor A circuit control limit not reached. anyone got any ideas :uhm:
  6. Dan Gliballs

    Dan Gliballs Active Member

    Similar problem here since Sunday!!! :(

    I bought the car with various leaks, and had a Samco Y-pipe and a few other bits and sensors replaced. It has been tight and making circa 300 bhp for 2 1/2 years since that. Sunday I took a chap out for a spin and it felt all flat.

    I'll dig my Ross-Tech out when I can be assed. Hope it's just a small hose leak,..........and one that's reasonably accessible lol

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