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Why Would It Do This?

Discussion in 'A3/S3 Forum (8L Chassis)' started by A3 T, Mar 9, 2014.

  1. A3 T
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    A3 T Lord Of The Rings

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    [Mar 9, 2014]
    For some reason while driving along at a steady speed (not fast) I hear the car dump the boost (not that there should be much boost to dump at this speed).

    Also sometimes while accelerating from a stop I hear the turbo start to spool up and then the boost gets dumpped and the turbo just spools up again.



    Any ideas what this could be (n75 maybe) ?
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  3. A3 T
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    A3 T Lord Of The Rings

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    [Mar 13, 2014]
    Anyone ?
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  4. cammage08
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    cammage08 Member

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    [Mar 13, 2014]
    Have you bypassed the n249? This little monkey will dump boost lile this if something is wrong...
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  5. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Mar 13, 2014]
    Sounds like its going into limp mode... you need to scan for fault codes in the first instance and post them up

    <tuffty/>
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  6. JudderMan
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    JudderMan Active Member

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    [Mar 13, 2014]
    I found a small hole in my TIP that is causing something similar. Friggin £100 worth of pipe that has been rubbing on a jubilee clip which I hadn't noticed. Gutted. (N249 delete too btw).
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  7. david7m
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    david7m Active Member

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    [Mar 13, 2014]
    Silicon plus a few wraps of black duct tape? Cheap bodge until a used one comes up :p

    Dave
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  8. JudderMan
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    JudderMan Active Member

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    [Mar 13, 2014]
    Well....I am from Newcastle....pikey bodge jobs are my forte ;)
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  9. A3 T
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    A3 T Lord Of The Rings

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    [Mar 13, 2014]
    Thanks for all the replies ;-)

    I've already done the n249 bypass (as shown in my sig) and I'm not getting any fault codes.

    Its also not going in to limp mode as it spools straight back up.

    Let me try and explain it a bit better..

    If you was to watch the boost gauge then at idle it would sit at -20, as soon as I start to pull away (smoothly not putting my foot down) the turbo quickly spools up and the boost gauge gets to about 0 then the boost dumps and the turbo spools up as it should at a normal pace.

    Could this be the n75 causing boost surge?
    #8
  10. Lavis89
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    Lavis89 Active Member Regional Rep

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    [Mar 14, 2014]
    I've had exactly the same problem for a long long time, a few people have mentioned having the same thing on VAG talk as well. No leaks, had it smoke tested a few times, no codes, took a trip up to bills and got it remapped and everything was fine when he scanned and smoked it, still happens, think it's always happened since i've owned the car
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  11. JudderMan
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    JudderMan Active Member

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    [Mar 14, 2014]
    Could it be your Bailey dump valve? Can you try an OEM one to check? Sorry I can't help with the N75 thing I still don't fully understand what it does/how it works.
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  12. A3 T
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    A3 T Lord Of The Rings

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    [Mar 14, 2014]
    I've tried the standard valve but it didn't make any difference (I've got a forge one on there now).

    Another thing I've noticed that's probably not related is that sometimes if I put my foot down it feels like its lacking power, almost like I've got it in the wrong gear.
    #11

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