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Possible cure for the annoying S3 over revving when changing gear

Crazypete00 Jun 8, 2010

  1. Crazypete00

    Crazypete00 Active Member Audi S3 Audi A4

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    First a quick background.

    Had the car for over 2 years, around about 18months ago my car had a new clutch slave cylinder fitted and since then i noticed the annoying over revving when changing gear. not so bad back then but a year later it started getting really bad. change at about 4k rpm and it would shoot straight up to 6krpm.

    Car - Audi S3 2001 facelift
    Jabba custom map before i bought the car
    not alot else done to it.

    So i replaced the clutch switch (the one on it was broken anyway. - didnt cure the over revving
    Replaced a N75 valve from another S3 which didnt have the problem - didnt cure it
    removed and cleaned TB then re-aligned - didnt cure it
    replaced the DV with a forge one. - didnt cure it

    But yesterday, i was checking the car over, checked the brake fluid res, rear left under the bonnet as if you are standing in front of the car. Noticed a rubber pipe directly above it which runs alongside my charge pipe had split, well gone brittle and cracked where it connects to a 90 degree bend. At the time all the garages had closed and i needed a quick fix to get me where i was going. so i used duct tape, taped the crack and the connecter so nothing leaked, plus a cable tie to make sure. - well this seems to of cured the over revving while changing gears. drove for around 350miles the past 2 days and its been great, it still does it very slightly but heared that remapped S3s so it slightly anyway to keep the turbo spinning.

    so anyone who has this annoying issue check your rubber pipes around the brake fluid res and see if you have any split.
     
  2. Y83OLK

    Y83OLK Hulk Smash!

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    The servo pipe?.
     
  3. s3dave

    s3dave TFSI Hybrid Supporter

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    interesting thanks...
     
  4. 5ean

    5ean S3 Owner VCDS Map User

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    Got any pics of said pipe?
     
  5. Matt82

    Matt82 Active Member

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    the only one it could be would be the servo hose, the other pipes would be hydraulic related

    definately get the hose changed.

    it says a lot about the places youve been taking your car to tbh
     
  6. Crazypete00

    Crazypete00 Active Member Audi S3 Audi A4

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    not sure its the servo pipe, it runs down behind the engine towards the turbo then 90 degree bend and follows the charge pipe down the front of the engine.

    what do you mean about the places ive been taking my car? it has dont 150k miles so its probably the age.

    ye getting a replacement today
     
  7. sportstractor

    sportstractor Chugger

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    Yeah its the servo pipe, Mine original and in perfect condition. When you rev your engine does air blow out of the crack, because if it does that means the pcv check valves are letting by which could be the reason its split in the first place.

    I may be wrong but pretty sure servo is ment to get vacuum only, unless there is a check valve futhur up the line?
     
    Last edited: Jun 9, 2010
  8. jonny87

    jonny87 Active Member

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    is the clutch switch correctly adjusted?
     
  9. Crazypete00

    Crazypete00 Active Member Audi S3 Audi A4

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    ye the new switch doesnt need adjusting, the pin doesnt click in and out like the old one, its the new revised switch.

    the picture below with the red line is the one thats split

    [​IMG]

    [​IMG]
     
  10. Crazypete00

    Crazypete00 Active Member Audi S3 Audi A4

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    you can see the green tape at the top were ive temporary fixed it.
     
  11. 5ean

    5ean S3 Owner VCDS Map User

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    What engine do you have as im 99% sure i dont have that hose?
     
  12. Crazypete00

    Crazypete00 Active Member Audi S3 Audi A4

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    its the amk engine
     
  13. 5ean

    5ean S3 Owner VCDS Map User

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    Hmmm gonna have a look at this when i get home as i have an AMK and im pretty sure i dont have that?
     
  14. Crazypete00

    Crazypete00 Active Member Audi S3 Audi A4

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    ok, maybe it should go under that top boost hose, but let me know as im 100% sure mines a amk.
     
  15. jonny87

    jonny87 Active Member

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  16. sportstractor

    sportstractor Chugger

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    i checked this, and noticed there is a oneway valve futhur towards the servo, which means that pipe it under positive and negative pressure where it split. So it will make it over rev, hesitant and hunt on idle if this pipe is damaged
     
  17. Crazypete00

    Crazypete00 Active Member Audi S3 Audi A4

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    ye just checked it, took the tape off and it started over revving again, what sportstractor said makes sense so replaceing it has sorted my over revving problem.:yahoo:
     
    Booth1982 likes this.
  18. Booth1982

    Booth1982 Member

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    Can someone post a picture of the hose that was replaced.? thanks in advance.
     
  19. Stuart B

    Stuart B Well-Known Member

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    it's maybe the strange connector pipe under the cross member near there master cylinder, mine has a jubilee clip on after it fell apart. It's like a 90 degree hard plastic push fit connector (ribbed)

    You can follow the pipe from the inlet manifold toward the master cylinder.

    Screenshot_20161117-220820.png
     
  20. AGB-S3

    AGB-S3 Member

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    There was a re-call on the VAC pipes ? , I had to replace many of the pre-formed rubber hoses , they had splits in them , solved a lot of hunting , especially with the air-con pump on and over run when changing gear .. still not 100% convinced the brake servo is not being fed positive pressure now and then .. may be a new one way valve would help if there is one on the BAM engine
     
  21. Tj 0785

    Tj 0785 Active Member Bronze Supporter Audi S3

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    Mine has done this for12-18 months tried a few clutch switches , no fault codes ,new clutch never got to the bottom of it. Is there a way to test if the servo is getting positive pressure
     
  22. AGB-S3

    AGB-S3 Member

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    seems to be issues round the break servo, some report it leaking vac - fixed with spraying silicone grease , past the in put shaft , other replacing it , not a simple job , audi seem to like vac valves , had problems with the 80CD years back and the strange pie-berg carb .. the ford xrx4xi was a pumped pressure system ... if I swap from acceleration to breaking .. sometimes I have a short [exciting] time before the breaks come fully 'on' ... with the engine off , I get about 30 seconds , before the vac has failed ... improved with new pipes

    don't see any simple way to test for + pressure or leaks , without some rubber bungs , hoses and a sensor

    G,
     
  23. AGB-S3

    AGB-S3 Member

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