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Finally got my s3 back ... but doesnt seem as quick ?

Discussion in 'A3/S3 Forum (8L Chassis)' started by motfree, Jan 25, 2011.

  1. motfree
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    motfree Member

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    Hi peeps ..
    Finally got my s3 back today after getting a new engine put in ..
    I bought an AGU block and put all my parts over from my broken APY motor ..

    Havent adjusted the actuator but just doesnt seem as quick at all .. but showing that its only boosting 10psi ( didnt have a gauge previously )

    just seems wierd that nothing has been adjusted that it feels that different

    anyone got any ideas ?
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  2. S3KO4
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    S3KO4 Member

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    is it mapped? agu has big port right! so the map you had would vary slightly to your small port.
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  3. motfree
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    motfree Member

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    Oh right so the only way really is to put the apy head on the agu engine ??
    I was told wouldn't make any difference .. So will it be ok if I just turn the boost up ?? Or do I need a new map ?
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    The engine should have turned the boost up by itself.

    You should at the very least have it checked on a dyno to ensure the fuelling is correct for the large port head though
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  5. Blackcupraa
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    Blackcupraa Member

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    Are you using the same ECU or the ECU from the donor engine?
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  6. motfree
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    motfree Member

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    Well previously was boosting at 18psi so must be something up .. So I need to put it on a dyno ?? Or just turn the boost up on actuator ?
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  7. motfree
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    motfree Member

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    Old ecu .. Been doing alot of research about this before I've done this and been told that engines are identical apart from injectors , turbo , and map :-S
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  8. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    You need to find out whats broken. Actuator doesnt need touched at all, ever.

    AGU has a large port head, your old engine has a small port one. AGU also has a higher 9.5:1 compression ratio compared with 9:1 in the S3.

    None of these things would take the boost pressure down from 18psi to 10 though, theres something else going on.
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  9. motfree
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    motfree Member

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    ok so vag-com best way ?
    didnt previously have boost gauge by the way just felt like it had abit more umph haha if that makes sence
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  10. badger5
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    badger5 RIP S3dave Site Sponsor

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    n75 valve on the right way round?
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  11. motfree
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    motfree Member

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    ill try that now .. just looked at the gauge and seems to be sticking to 6 / 7 psi which ive been told is standard psi ?
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  12. motfree
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    motfree Member

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    just been out can only fit on 1 way ... put checked connectors and theyre fine .. but thread on actuator is literally only about 1" threaded any idea how much should be for 20psi as this is what the car was mapped to ??
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  13. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    Sounds like limp mode to me, Have you checked for codes?
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  14. motfree
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    motfree Member

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    nope not yet but dash doesnt have any lighs on :-S !!
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  15. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    that is not a given for limp mode. Have a look when you get a second, i am sure it will shed some light on the subject
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  16. motfree
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    motfree Member

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    oh thought a light came on .. might just take it to get pluged in tomorrow morning ...
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  17. motfree
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    motfree Member

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    by the way does it matter that ive put the apy engine n75 valve on ? or should it be the agu n75 valve ?
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  18. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    You should be running the APY valve, but they're probably the same anyway.
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  19. motfree
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    motfree Member

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    Going to order one of those vag com things off eBay .. As I'm baffled about this one and the mass airflow meter is 2 months old so don't know ..
    My mates convinced i just need to turn the boost up ( thread actuator in more )
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  20. s3dave
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    s3dave TFSI Hybrid

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    Try running it carefully with the actuator hose off.... dont belt it and see if your boost increases...
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  21. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    The Actuator opens at 5psi.

    If you thread it in too much, you'll get boost creep.

    The ECU controls the boost using the N75 valve etc. So long as theres enough preload to hold the actuator closed it will be fine.

    No-ones touched the turbo, so why are you convinced it needs adjusted?
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  22. motfree
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    motfree Member

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    That means that the boost will just go really high though won't it ?? Or will it only go as high as the actuator is threaded ??
    Is this to see if it's the turbo stopping it from boosting over 9psi or if there's a fault on a sensor eg n75 valve or something ?? As if it boosts Upto like 20psi like it did must be sensor must it ?? I'll try that tomorrow
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  23. Welly
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    Welly VX220 SC Driver :)

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    Bolting an AGU engine is, and having it setup the same way, with the same boost, should make the car feel exactly the same, if not a little quicker. That was what I experienced with mine.

    If you were running 18 PSI, and are now running 10, that would certainly explain why it doesn't feel as fast - less torque simply.

    The engine is simply the engine, it bolts in and works. Thats not to say that a sensor somewhere has been damaged in the transfer process - easily done.

    You need to go out and log it with VAG COM really to investigate what the requested vs actual boost is.
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  24. badger5
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    badger5 RIP S3dave Site Sponsor

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    confirm which pipe goes where on your n75..

    long tail goes into tip, boost goes into middle off charge pipe, and the other one goes to wastegate actuator
    your boost pressure appears to be wastegate pressure only, which if plumbed wrong could be your issue.

    std boost is 9-12psi on S3's

    check electrically it works in vagcom, output tests
    Last edited: Jan 26, 2011
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