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ecu restricting boost??

Discussion in 'A3/S3 Forum (8L Chassis)' started by malcolm30029085, May 14, 2010.

  1. malcolm30029085
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    malcolm30029085 Member

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    [May 14, 2010]
    hi i have started many threads about this ongoing issue with my apy s3.

    basicly the car will only boost to 10psi exactly!!
    checked for leaks
    changed maf
    changed dv valve
    changed n75 valve
    checked turbo and wastgate!!!!!!!
    i disconnected the acutator pipe and drove it (unlimmited boost) and it was fine drove perfectly and boosted well past 10psi!!
    yhe only thing not standard is a de-cat it has not been mapped would this be the cause of it????????
    cheers
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  3. Welly
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    Welly VX220 SC Driver :)

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    [May 14, 2010]
    Hmmmm, hard to say. The N249 valve also deals with boost control, so may be worth bypassing as a test.

    Have you scanned it for fault codes?
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  4. Welly
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    Welly VX220 SC Driver :)

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    [May 14, 2010]
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  5. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [May 14, 2010]
    bring it down and I can take a look
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  6. Welly
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    Welly VX220 SC Driver :)

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    [May 14, 2010]
    ^^ I'd go with that personally....
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  7. malcolm30029085
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    malcolm30029085 Member

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    [May 14, 2010]
    Ok mate where abouts are you??
    Forgot to mention that I have done the bypass and also have a brand new map sensor on there aswell!!
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  8. malcolm30029085
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    malcolm30029085 Member

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    [May 17, 2010]
    just a quick update i have the car booked in at mrc tunning in banbury next week so hopefully they can she some light on it, also just thought id mention that the car actually struggles to do 80 on the motorway let alone put you back in your seat!!!
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  9. Boggle
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    Boggle Member

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    [May 17, 2010]
    i had trouble going over 60 and got it fix was told it had a hole in a pipe going to the turbo hope this helps
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  10. Welly
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    Welly VX220 SC Driver :)

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    [May 18, 2010]
    Bloody hell, that must of been some serious kind of hole....
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  11. Welly
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    Welly VX220 SC Driver :)

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    [May 18, 2010]
    Yeah, hopefully they can tell you. Sounds like it's going in to limp mode to me to be honest, but they will be able to tell you more.
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  12. malcolm30029085
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    malcolm30029085 Member

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    [May 18, 2010]
    yhe thats what i thought but dont understand whats setting it off???
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  13. Welly
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    Welly VX220 SC Driver :)

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    [May 18, 2010]
    Could be a million things. OK, not a million, but plenty of things can cause it.

    Overboost being one of them.

    May not be a faulty N75 valve on your motor, may be the ECU keeing the N75 valve open to invoke limp mode, landing you with your problem.

    10 PSI is a lot for limp mode - but maybe someone has 'fixed' the actuator to make it open at higher boost pressure.

    This would account for your overboost, as well as 10 PSI in limp mode....

    Just my thoughts.

    The other, and most obvious possibility is that the ECU is giving you limp mode as it things the cat is shagged...
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  14. malcolm30029085
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    malcolm30029085 Member

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    [May 19, 2010]
    yhe that would make sense, well see what mrc has to say on sat i will let you no what is was when i do!! cheers
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  15. mark_sarah
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    mark_sarah Limp mode!

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    [May 22, 2010]
    Any news on this?
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