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Vagcom results after N249 bypass and reversed DV

Discussion in 'A3/S3 Forum (8L Chassis)' started by Westy, Dec 13, 2009.

  1. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 13, 2009]
    I ripped out all the N249 gubbins today and reversed the dv to see what effect it will have. These were my results:

    before:

    257 bhp
    271 lbft
    boost spiked at 20 psi then held at 18.5 psi

    After:

    245 bhp
    271 lbft
    boost peaked at 22 but then it gradually dropped off to 15 psi by 5500rpm!

    I'm guessing that my N249 was faulty because I used to get a fluttering noise that has now gone but maybe the reversed dv is leaking boost.

    Any thoughts?
    #1
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  3. m444ty p
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    m444ty p Member

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    [Dec 13, 2009]
    What dv do you have?
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  4. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 13, 2009]
    Forge 007p with yellow spring
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  5. Prawn
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    Prawn My other car is a MINI!!!!

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    [Dec 13, 2009]
    almost certainly the DV leaking mate, when run backwards it can creep open....
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  6. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 13, 2009]
    Good that's what I was hoping! I'll change the dv back later and run some more tests. Hopefully with the N249 ripped out I should hold a bit more boost than before.
    #5
  7. Welly
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    Welly VX220 SC Driver :)

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    [Dec 13, 2009]
    Post results, interested to know difference....
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  8. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 20, 2009]
    Ok I'm a bit miffed! I've just done another run with my DV back to the normal position and I got almost identicle results to having a reversed DV:

    247bhp
    274lbft
    22psi from 2800rpm to 4100rpm then it starts dropping off till it reaches 15psi at 6000rpm!

    Now how was I getting 257bhp 6 months ago on a warmer day (12 degrees) with less boost with the N249 connected? Could it be that where the N249 is no longer able to open the DV I'm holding more boost and my standard tip is collapsing at 4000rpm?

    any suggestions guys?
    #7
  9. s3ollie
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    s3ollie Member

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    [Dec 20, 2009]
    how are you working out your BHP figure?
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  10. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 20, 2009]
    Using block 120 for bhp/torque and block 115 for boost in VCDS then I Used the spreadsheets off the Ross tech website.
    #9
  11. DJ_Troopa
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    DJ_Troopa K1 Driver

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    [Dec 21, 2009]
    Nice one for testing this out Westle. I reversed my DV and it feels exactly the same as when it was the normal way around but obviously it has the loud chirp noise.

    Will be good to see if there are any differences when you get your lil problem checked out and tested again.

    Keep us posted :thumbsup:
    #10
  12. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Dec 21, 2009]
    Well I am running a yellow spring in my DV as opposed to the standard green one so I dont know if that makes any difference but reversed and normal produced near identicle results.

    It appears that my timing is being pulled from 4krpm onwards which ties in to my boost drop above so I'm trying to understand what could be causing it!
    #11

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