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Problem after N249 Valve bypass.

Discussion in 'A3/S3 Forum (8L Chassis)' started by S3 Paul, Jan 27, 2012.

  1. S3 Paul
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    S3 Paul Active Member

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    I did the bypass that is common place now on our engines some time last year, Everything felt good,
    The car still drives fine, But due to my boost going a little higher than before i decided to vag com the car last week,
    I have one fault code... 17608
    Boost Preasure Control Valve N249 mechanical malfunction
    intermittent.
    I cleared the code as the valve is still plugged in but no longer piped up...
    This morning a rechecked the codes on my way to work... its back again !
    If the valve is plugged in but not plumbed in how can the ecu tell it isnt working ?
    I used my spare N249 as i removed and kept all the old pipe work complete and as one piece,
    Is the code that the N249 itself is faulty ? or that the car knows it isnt doing its job any longer??
    #1
  2. Alex C
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    Alex C Well-Known Member

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    maybe if the ECU tries to dump boost using the N249 and can see that the boost hasnt been dumped from the MAP? But i didnt think that this threw a fault else everyone would have this issue?
    #2
  3. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Unless the 28psi is effectively overboost, and the ECU's trying to reduce the pressure by opening the DV...

    I'd be carefully checking the N75 pipework to make sure you've not knocked something off.
    #3
  4. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    It can tell its not working as thats the code it throws when it sees a boost deviation or wants to dump boost as its detected a problem and can't because even though it can operate the N249 it can't see the boost drop using the MAP sensor..

    This is normally an issue with mapping or that something is wrong and you are either generating more boost than the map is expecting... could be an N75 issue, boost leak or something else...

    <tuffty/>
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  5. S3 Paul
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    S3 Paul Active Member

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    Well I'm not sure if it's linked but...
    Last night under gentle loading ( fourth gear on long road) the boost gauge was up then down to 11 then back up to 18
    No jurking but the car didn't feel as lively.
    Just heading out for a nose under the bonnet to check for obvious problems.
    Then maybe if I get time a boost leak test with the bungs and my compressor)
    #5

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