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vac hoses

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

  1. malcolm30029085
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    malcolm30029085 Member

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    [Mar 8, 2010]
    dose anyone know who sells upgraded vaccume hoses for the s3??
    having trouble with boost at the minute only getting 5-7psi unless i boot it through every gear and then im only getting about 11psi. have replaced n75 (j) and dont think the maf would cause these symptoms.
    cheers
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  3. Matt82
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    Matt82 Active Member

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    [Mar 8, 2010]
    rig up something to test for boost leaks and then replace as necessary
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  4. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Mar 8, 2010]
    5-7psi is actuator pressure... prob going into soft limp because you have a 'J' valve fitted... 11psi sounds about right for an unmapped car...

    Replace the 'J' with the correct valve in the first instance, the only 'upgrade' to vac hoses is to remove unnecessary ones and use silicon tubing of the right size...

    <tuffty/>
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  5. s3 man
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    s3 man Member

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    [Mar 8, 2010]
    isit worth changing the n75 to the j.or isit best to leave it how it is?
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  6. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Mar 8, 2010]
    The 'J' valve is slightly electrically different to the std N75. Its inherent 'delay' in reacting to initial boost coming on is what gives a greater boost spike before it manages to catch up with it all and control boost as it should... this tends to catch the ECU out as it sees more boost than its expecting and will go into limp mode...

    Worse case scenario could be that the boost spike cause a huge amount of torque and bends a rod....

    <tuffty/>
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  7. malcolm30029085
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    malcolm30029085 Member

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    [Mar 9, 2010]
    can the n75 j be adjusted to stop limp mode because at the moment my s3 is not boosting properly and if i dose get a high boost spike it goes straight down to 5 psi again !!
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  8. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Mar 9, 2010]
    No mate, just change it back to the proper N75 valve.... 'J' valves on 1.8t's with MAP sensors don't work...

    <tuffty/>
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