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boost issues

Discussion in 'A4/S4 forum(B5 Chassis)' started by paulrom, Jan 23, 2009.

  1. paulrom
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    paulrom New Member

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    [Jan 23, 2009]
    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 ??????????
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  3. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Jan 23, 2009]
    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...
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  4. stapo69
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    stapo69 All hail the mighty quattro!

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    [Jan 23, 2009]
    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.
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  5. Siena
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    Siena Active Member

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    [Jan 24, 2009]
    A faulty MAF will also give rise to sporadic performance / boost issues.
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  6. Digger01
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    Digger01 New Member

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    [Jan 31, 2009]
    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:
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  7. Dan Gliballs
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    Dan Gliballs Active Member

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    [Feb 11, 2009]
    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
    #6

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