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My s3 is driving me mad

Discussion in 'A3/S3 Forum (8L Chassis)' started by Andrew@A.L.D, May 23, 2010.

  1. Andrew@A.L.D
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    Andrew@A.L.D Cylinder Head Master

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    [May 23, 2010]
    I'm not having much luck with this car as its seam to be problem after problem

    Now i'm getting this code

    17963/P1555 - Boost Pressure Control: Upper Limit Exceeded
    Possible Symptoms
    Reduced power output
    Limp mode
    Possible Causes
    Boost Pressure too High
    Hoses/Pipes incorrect connected, disconnected, blocked or leaking
    Charger Pressure Control defective
    VNT (variable nozzle turbo): nozzles stuck
    Solenoid Valve for Boost Pressure Control (N75) defective
    Possible Solutions
    Check Hoses/Pipes to/between Components
    Check Solenoid Valve for Boost Pressure Control (N75)
    Check / Clean / Replace Charge Pressure Control
    Check / Clean mechanism for variable nozzles


    I've checked hoses and pipes
    I got a new N75J a bit ago ( on a APY )
    Cleaned things and so on

    I've not done many miles in it since its rebuild, managed to get out in it this weekend

    Also the dump valve is still not dumping even after a service, it does work and you can hear in move when you take the vacuum pipe off and suck on it
    #1
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  3. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [May 23, 2010]
    you have a totally different engine now to what the ecu is expecting to see, so to this would all go hand in glove

    you have a boost deviation +250mb over requested hence the fault code.. mbc will clip and give you adjustment, but your mechanical mods outweigh the ecu's expectation.

    dv not working... how do you know its not working?
    whats it doing?
    #2
  4. Andrew@A.L.D
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    Andrew@A.L.D Cylinder Head Master

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    [May 23, 2010]
    Just been out in it and plumbed in a boost gauge, it runs 5psi then 20psi then 5 and back to 20 again, its jump about a bit.
    The engine can run smooth on the spot but put it under load and it can spit and fart then its off.

    I can't hear it at all, all i can hear is wastegate chatter and no dump valve like it did before the engine build, strange as there is vacuum from the inlet
    #3
  5. Andrew@A.L.D
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    Andrew@A.L.D Cylinder Head Master

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    [May 23, 2010]
    If i swap back to a N75F valve will that help as i have the J valve on right now
    #4
  6. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [May 23, 2010]
    Having a 'J' on isn't gonna help tbh...

    Needs logging tbh, see what has changed... at a guess the turbo is spooling earlier catching the ecu out... 5psi sounds like soft limp.... logging may well help give you an idea but as Bill says you have changed the characteristics of the hardware that much the std map is not going to be working well... try disconnecting the N75 electrically (leave it plumbed in though) this will prevent the turbo over boosting while you get the rest sorted and it up and running.... it will throw a few codes but at least you can see if the engine will run ok enough to get you going.... I would imagine that you are going to be needing a stage 3 map sooner rather than later though

    <tuffty/>
    #5
  7. Andrew@A.L.D
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    Andrew@A.L.D Cylinder Head Master

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    [May 23, 2010]
    It runs but i have done what you said

    It feels like the ignition timing is off too but i'll try and get it logged

    Turbo feels like it will come in very early

    I'll have to get it booked in for a mapping as i would like to drive it and to get rid of the water thats still in the exhaust from when the head gasket went
    #6
  8. Andrew@A.L.D
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    Andrew@A.L.D Cylinder Head Master

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    [May 23, 2010]
    Runs better without the N75 plugged in and i can hear the dump valve working now thank god as i was worried about the damage it could do to the turbo, just greased it a bit more, still running on the green spring but have a yellow one when mapped
    #7
  9. Andrew@A.L.D
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    Andrew@A.L.D Cylinder Head Master

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    [May 24, 2010]
    Booked in at RS Tuning in leeds to take some logs to find out whats going on
    #8

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