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N249 Bypass on a 2001 AMK car ( with a BAM engine if it makes any odds)

Discussion in 'A3/S3 Forum (8L Chassis)' started by S3 Paul, Nov 1, 2011.

  1. S3 Paul
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    S3 Paul Well-Known Member Regional Rep

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    [Nov 1, 2011]
    From time to time my car seems to be "off the money"
    I mean some times feels a little flat and not as eager as it does at other times.
    Some days i remember why i have the car when it makes me smile ,
    Other times it could easy be standard power, Among things ive been told to try is the N249 bypass. Check the condition of my Forge DV ( piston and seat) Vac hoses? And a small boost leak? The car still makes 22psi and the AFR doesnt change when the car is on it or off.
    So if the Bypass is as straight forward as i keep being told i will try it... Does anybody have any tips as to whats diffrent from the other engine codes??
    #1
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  3. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Nov 1, 2011]
    N249 bypass is simple on AMK/BAM engine codes...

    3mm id silicon vac pipe from the outlet under the inlet mani where the original pipe fits on next to the FPR pipe just above where the alternator is... take it striahgt to the top of the DV... leave the N249 electrically plugged in and jobs done...

    <tuffty/>
    #2
  4. S3 Paul
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    S3 Paul Well-Known Member Regional Rep

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    [Nov 1, 2011]
    Thats great news. Thankyou
    Does it sound like a good idea to try it?
    I know its said to be a worth while mod long term but im trying to find the cause of my moody S3
    #3
  5. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Nov 1, 2011]
    Bit more responsive, less pipes and **** laying about the engine bay... worth a punt...

    <tuffty/>
    #4
  6. Ashley g
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    Ashley g Member

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    [Nov 2, 2011]
    3mm hose? ********. Just ordered 4mm id hose, is that going to be too big?
    #5
  7. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Nov 2, 2011]
    3mm/4mm should be fine... use cable ties to secure

    <tuffty/>
    #6
  8. S3 Paul
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    S3 Paul Well-Known Member Regional Rep

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    [Nov 2, 2011]
    Well ive had a good old hunt around the engine bay... I never realised the bypass was so obvious !
    Just a couple of questions...
    My Boost gauge feed is from the pipe that goes to the top of the DV... will it make the needle flicker as it did when a garage moved it to the FPR?
    What actual function does the valve have? I know it controls the DV but when and why??
    As for my "Moody" performance...
    I have found yet another split hose.
    This time its the one on the left hand end of the inlet , the one that seems to double back on itself?
    Im sure ive seen silicone ones on ebay and the like... As the one on the car has managed 10 years do i upgrade or simply replace??
    #7
  9. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Nov 2, 2011]
    N249 is a switching valve... vacuum is used to open/keep open the DV while boost keeps it shut... the N249 and the vacuum tank is there so the ECU can dump boost using the DV if it doesn't like something... the vacuum tank is there so it has vacuum to enable it to dump under boost which it obviously can't if it just had a vacuum pipe going to it...

    The ECU gets ansy, switches the N249 so instead of the DV getting the feed of boost from the inlet mani it gets the vacuum in the vacuum store enabling it to operate the DV and dump boost... phew!

    <tuffty/>
    #8
  10. SiGainey
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    SiGainey Member

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    [Nov 2, 2011]
    Forge do a replacement for the bam engine I think...
    #9
  11. Dan-Jnr
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    Dan-Jnr Active Member

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    [Nov 3, 2011]
    I did this last night on my BAM, solved my boost drop.
    I joined the thinner vacuum hose to the thicker dv hose.
    You can see the join just near the white t-piece.

    [​IMG]
    #10
  12. sean_s3
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    sean_s3 Member

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    [Nov 3, 2011]
    @ Paul . The U shaped pipe I believe is the brake vacuum hose.
    #11
  13. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Nov 3, 2011]
    Paul I had the exact same issues as you did once apon a time and most of it is hose related.

    I changed all boost hoses and as many hoses as I possibly could for silicone hoses. The 2 main area I found helped on keeping consistent power is to do the N249 bypass and also fit a catch can and vent to atmosphere.
    #12
  14. S3 Paul
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    S3 Paul Well-Known Member Regional Rep

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    [Nov 4, 2011]
    Thanks for all the help.
    I understand the need for leaving the N249 electricaly connected but do i need to leave the pipes on? should i blank them off? leave them open ?
    #13
  15. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Nov 4, 2011]
    Leave all connections on the valve open and remove the hoses from them.

    Like this:

    [​IMG]
    #14
  16. S3 Paul
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    S3 Paul Well-Known Member Regional Rep

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    [Nov 4, 2011]
    Is that a T piece i see?
    Is it for a boost gauge or something?
    Ive just dont this Mod today, The car feels more responsive, DV is a bit more snapy if that makes sence?
    I have a vac leak on the brake vac hose and my new part willnt be here till next week, But from how the car felt on the way home to how it felt on the short test drive.... much better, Cant wait till ive got the hose on...
    #15
  17. sean_s3
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    sean_s3 Member

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    [Nov 4, 2011]
    Paul which Brake vacuum hose did you buy ? I've seen silicone ones ranging from £10 - £20 and i'm replacing this hose myself in a few week.

    Cheers.
    #16
  18. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Nov 4, 2011]
    Yes mate T is for my boost guage. DV is a lot more snappy due to the vacuum not having to go round that stupid system onto the N249 valve ;)
    #17
  19. S3 Paul
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    S3 Paul Well-Known Member Regional Rep

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    [Nov 4, 2011]
    I realy wish i had done this ages ago... but every new little mod makes you smile so... even with my hose still in the post... a happy test drive,
    How ever...
    On a not so good note... ive found the next "problem" im guessing not only i will have seen...
    The wires to the coil packs . The insulation on nearly all of them had split so bare wires right left and centre!
    Ive repaired what i can so now hope all is well.
    Bloody cars !
    #18
  20. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Nov 4, 2011]
    Paul try to do the catch can at some point, this gets rid of all the perishing hose in the breather system. I guarantee that you have a split in it somewhere.
    #19
  21. S3 Paul
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    S3 Paul Well-Known Member Regional Rep

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    [Nov 4, 2011]
    I opted for one from creative ... something or another,
    Sorry i cant remember just now, It was £12.98 with postage... it was the only place that had one in stock, I will let you know how it fairs...
    #20
  22. sean_s3
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    sean_s3 Member

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    [Nov 4, 2011]
    Sounds like the same one I've seen , if its decent quality then its a steal at that price.

    Cheers.
    #21
  23. S3 Paul
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    S3 Paul Well-Known Member Regional Rep

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    [Nov 4, 2011]
    I know we have all seen it before... but heres how it looks now and what came off.
    I had a spare N249 so used that so i could leave what i took off in one complete mess.
    [​IMG]

    [​IMG]

    [​IMG]
    This is the mess now sat in a box in my flat.
    Where it will stay unless i hear some shocking news that my car will explode unless i refit it.
    #22
  24. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Nov 4, 2011]
    Throw it in the bin mate ;)
    #23
  25. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Nov 4, 2011]
    Welcome to the club.... :thumbsup:

    <tuffty/>
    #24
  26. S3 Paul
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    S3 Paul Well-Known Member Regional Rep

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    [Nov 7, 2011]
    The hose turned up today... to be fair it looks more than upto the job, I will hopefully fit it tomorrow dinner time.
    ...
    [​IMG]

    [​IMG]

    [​IMG]

    Aslong as it fits... im happy.
    #25
  27. Lemon S3
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    Lemon S3 Alex

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    [Jun 13, 2012]
    Can this be done on an APY? If so, how much different is it?
    #26
  28. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Jun 13, 2012]
    Link for APY is in the stickies...

    <tuffty/>
    #27
  29. Lemon S3
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    Lemon S3 Alex

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    [Jun 13, 2012]
    #28
  30. Gops
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    Gops 6th gear @7000rpm

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    [Jun 13, 2012]
    It's easy on APY, did mine! Advice, be careful with the n112 valve. The clamps on the pipes make it hard to take the pipe off and breaks the nipple on the valve! Buy 2 t-pieces just incase lol. Catch can is my next thing to eliminate split pipes!
    #29
  31. karl210
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    karl210 Member

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    [Jun 13, 2012]
    not sure why everybody uses silicone pipe, on mine all i did was take the pipe from the inlet mani - the n249 and take it off the n249 end. Then i took the pipe from the d/v to the n249 off from the n249 end and the pipe from the inlet mani pushed straight into the d/v pipe and is secure enough, 2 min job
    #30
  32. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Jun 13, 2012]
    The whole point is to 'bypass' the N249... not sure what you have done here... yes on the AMK/BAM (non SAI engines) its as easy as taking the pipe from the inlet mani direct to the top of the DV (hence the reason most use a single piece of silicon as its an easy and cheap way to do it) but can't picture what you have done here...

    Can you explain it a little more as others will read this and get a little confused...

    <tuffty/>
    #31
  33. karl210
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    karl210 Member

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    [Jun 13, 2012]
    Yeah im not the best at explaining things....
    You can see the pipe from the d/v that went to the n249, i have connected it straight to the pipe coming from the inlet manifold, they fit straight into each other, heres a pic ive just taken:
    [​IMG]


    My engine is amk by the way
    #32
  34. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Jun 13, 2012]
    Ah... ok... you have just pushed the smaller hose into the larger one?... not ideal tbh... potential for boost/vac leaks and on mapped boost the possibility for them to pop apart... I have seen this on clamped charge pipes with no beading so a pipe pushed into another isn't something I would be doing...

    tbh silicone vac hose is cheap enough to buy from ebay so it s a no brainer to replace the whole thing...

    <tuffty/>
    #33
  35. Lemon S3
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    Lemon S3 Alex

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    [Jun 14, 2012]
    Does your n112 valve have 3 nipples? two next to each other (one 90 degree to the other) and one at the other end next to the plug? if so where does the nipple by the plug go or is it bunged or vented to atmosphere?
    #34
  36. vrbob
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    vrbob Thats no Moon, Thats a space station!

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    [Jun 16, 2012]
    Did this today on my BAM engine.

    Very straightforward once you understand what your looking at. I bought a 1m length of silicone pipe 3mm internal diameter off ebay for £2 delivered. this is easily enough to do the job and keep it neat i followed tuftys advice and used small cable ties to hold the pipe on to the DV etc.

    Decided to keep the plate the N249 was fitted to ontop of the block like others have to hold the N249 but only used to screws to make it easy to remove when changing plugs etc.

    Will see if i notice any difference
    #35
  37. rhubarb4
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    rhubarb4 Certified Jardo Slayer

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    [Jun 16, 2012]
    Let us know what you think as I feel its more responsive and punchy.

    Chris.
    #36
  38. S3_chris 11
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    S3_chris 11 Member

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    [Jun 30, 2012]
    found this on a cupra r site
    [​IMG]

    im yet to do this to mine but possibly attempt tomorro but only have 5mm id piping left although it seems to fit fine on the outlet on the underside of the inlet and is on securely

    [​IMG]
    #37

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