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Losing boost...

Discussion in 'A4/S4 forum(B5 Chassis)' started by Geeman, Apr 6, 2009.

  1. Geeman
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    Geeman Low Life

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    If I give my '00 (83k) 1.8T Sport a fair old boot and take it through the rev range quite aggressively I sometimes lose turbo boost altogether.

    I don't do this very often, so it's not a major issue right now, but I'm sure it could turn into one in the future.

    Once I come to my destination, I switch off, do what I need to do and come back to the car and everything is fine again.

    Am I right in thinking it's the 'N75 valve' that causes this... or is it something more serious? Will the fact that it's been re-mapped have anything to do with it? I've not got any receipts for the work carried out (previous owner lost it) but I do know it's a LOT faster than a standard 1.8T.

    Cheers for any help...

    Giles
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  2. Geeman
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    Geeman Low Life

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    Bueller...? Bueller...? Anyone...?
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  3. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    It could be the map, or it could be the N75 valve allowing the boost to spike too much. Do you have vagcom and have you got any fault codes showing up?
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  4. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    You need to pull he codes, if she is hitting limp mode, it will have regisered a reason
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  5. Geeman
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    Geeman Low Life

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    Found a few things wrong with it today while we were replacing the timing belt (what a pig of a job!)

    There were TWO dump valves on it... the standard recirculating one in the correct place, then an adjustable atmospheric dump valve between the two outlets on the air intake pipe...?!?!?! (it's got a cone filter on it).

    So, we took the aftermarket item and placed it where the standard one was and then put the engine breather back into the intake pipe and disconnected the thin air-pipes that had been t-boned off the inlet manifold.

    God knows what the person who put this together was thinking...

    Not run it again yet though as I'm waiting on auxilliary drive belts to finish the job off.

    Will let you know if it makes any difference tomorrow when I finish the job off... hopefully - if I can find the belts I need!
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  6. Geeman
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    Geeman Low Life

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    Think I've fukked up the dump valves by replacing/moving them.

    It's now only half as powerful as it was before. Think I need to get it all back to standard... so I need to find a donor 1.8T for some pipe-work.

    Anyone know of a vehicle that's willing to donate pipe parts?
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