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N249 Bypass Guide (AUM).

Discussion in 'A3/S3 Forum (8L Chassis)' started by A3 T, Jun 12, 2011.

  1. A3 T
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    A3 T Lord Of The Rings

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    [Jun 12, 2011]
    My threads seem to just amount to nothing recently but thought i would ask this anyway.....

    Is there a guide to do the n249 bypass on the aum engine?


    I've found loads of guides for other engines but there always a comment about it being a bit different on the aum.


    Also I've read about using some sort of resister so that everything can be removed after the bypass.


    A before and after pic would be good to show what's been changed ;)
    #1
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  3. ja3mie
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    ja3mie A3 1.8t Quattro Sport!

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    [Jun 12, 2011]
    i have a different engine, but after reading loads of guides that confused me..

    basicly, you need to find out where the pipe comes from the inlet manifold to the n249 valve..

    take that off.. run a new pipe to the dump valve from the nipple on the inlet manifold you just took off.

    then take off all the other pipes etc that are related.

    just leave the actual valve electronicly plugged in and hide it away (so it doesnt bring mess the ecu) rather than trying to get the right resistor :)
    #2
  4. DenCar
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    DenCar Member

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    [Jun 12, 2011]
    What are the benefits of doing this?

    DC
    #3
  5. Gavin G
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    Gavin G Member

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    [Jun 12, 2011]
    #4
  6. Alex C
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    Alex C Well-Known Member

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    [Jun 12, 2011]
    why is the AUM different to any other 1.8T when doing the bypass, i cant believe that it is, someone enlighten me

    Wellys guide is slightly more involved because he had secondary air injection to deal with as well

    And why the UK mkivs AUM guide Ts into the FPR line i have no idea, it means he has to plug the original line. Where as if he simply ran the pressure line from the inlet manifold (from the original n249 connection) to the top of the DV he wouldnt have to bodge any plugs in hoses and could remove everything...??
    #5
  7. ja3mie
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    ja3mie A3 1.8t Quattro Sport!

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    [Jun 12, 2011]
    yeah dont T into the FPR line, i done this at first!

    improved DV responce, louder DV noise aswell...

    and the N249 valve controlls boost via the DV for traction control.. and the ecu sometimes decides to dump boost for no reason!

    so by doing the bypass, your only getting total boost (almost) without the ecu deciding otherwise!
    #6
  8. A3 T
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    A3 T Lord Of The Rings

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    [Jun 13, 2011]
    Thanks for all the replies everyone ;)


    I have seen the link link above but I've also read that you shouldn't tap into the fpr so I'm looking at a guide showing the correct way (not tapping into the fpr....lol) to do it.

    Also its a shame that there wasn't a picture showing what it should look like once its all been done.

    From reading it it looks like you would just T the hose on the fpr and run your own pipe to the top of the DV like this:

    [​IMG]
    #7
  9. Alex C
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    Alex C Well-Known Member

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    [Jun 13, 2011]
    Here is Welly's guide, he has had to do the pipe work for the SAI, so assuming that you do not have SAI then Wellys guide is a bit different but just apply some logic

    http://www.audi-sport.net/vb/general-technical-how/84402-n249-bypass-how-2000-s3-but-same-many.html


    This is Jamies recent threads when he got a bit lost with the n249 bypass

    http://www.audi-sport.net/vb/a3-s3-...19-n249-removal-help-please-pic-enclosed.html
    http://www.audi-sport.net/vb/a3-s3-forum-8l-chassis/121414-just-fitted-my-dv.html

    And from Wellys thread some pics of the bypass done by jonny87

    ...

    he has used red pipe, he has connected one end of the red pipe to the diverter valve (pic 1) take the other end of that red pipe and attach it to the nipple on the inlet manifold where the original N249 pipe work was connected (pic 2)... (he T'd it under the inlet manifold because he has SAI, but ignore it if you dont, i.e. no need to T)

    ...so...one pipe...two ends...two connections...and much confussion. I know these pics are for an s3 but same concept, 1 inlet manifold, 1 diverter valve and 1 silicon 4mm ID pipe.

    and Jonny's pic #3 shows the N249 valve with all of the pipe work removed but still electricaly connected and nicely stowed away

    hope this helps
    #8
  10. A3 T
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    A3 T Lord Of The Rings

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    [Jun 13, 2011]
    Thanks mate ;)
    Ill have a look at it when I get home on the pc.
    #9
  11. A3 T
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    A3 T Lord Of The Rings

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    [Jun 13, 2011]
    Just had a quick look and it looks a lot more complicated than running a hose from the top of the dv to the manifold.....LOL
    #10
  12. Alex C
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    Alex C Well-Known Member

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    [Jun 14, 2011]
    LOL.....indeed, i am trying my best here :)

    Just because it looks complicated doesnt mean the fix is, one of the reasons the bypass is done is because the pipe work is complicated therefore there is so much potential for a leak somewhere. The diverter valve opens when there is a vacuum in the inlet manifold protecting the turbo from pressure surge. The reason for all the **** involved with the N249 valve is that audi wanted the traction control to be able to cut power when it felt the need. OK, so what if your wide open throttle mid corner and the ESP wants to open the DV to save you from yourself? It uses the vacuum in the inlet manifold to open the DV...ah, but no, there is no vacuum because you are WOT. So how does it open the DV? It uses the vacuum reservoir, a reservoir of vacuum that it uses just in case. So how does this vacuum reservoir always have vacuum in it? Well thats where all of that complicated pipe work comes in with its loops and one way check valves, so yes it looks complicated but the basic function is very very simple. If you do the N249 bypass, i.e. remove the vacuum reservoir and the need for the N249 then you return to the simple operation of the DV i.e. it opens when there is a vacuum in the inlet manifold.


    Do you have SAI? Secondary Air Injection? YES/NO

    YES...

    Follow wellys guide http://www.audi-sport.net/vb/general-technical-how/84402-n249-bypass-how-2000-s3-but-same-many.html

    run a 4mm ID pipe from the top of the DV to a T piece. Take a pipe from one of the remaining two T piece outlets and connect it to the inlet manifold where your original N249 pipe work connected. Take a second pipe from the third and final outlet of your T piece and connect the other end to the N112 valve (this is the valve that is involved with your SAI (secondary air injection)

    This is Wellys pic of the end result for cars with SAI. To be fair I thought Wellys guide was spot on and clear

    [​IMG]

    Do you have SAI? Secondary Air Injection? YES/NO

    NO...

    see post #8


    we are trying ;)
    Last edited: Jun 14, 2011
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  13. A3 T
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    A3 T Lord Of The Rings

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    [Jun 14, 2011]
    Thanks mate ;)


    TBH. I think your the only one that stuck with me in all my threads (everyone else gives up) .....lol



    I don't know why i cant get my head around doing this.


    I'm not sure what the secondary air injection is but unless its not fitted as standard then I'm sure i don't have it.....lol


    Here's a pic of my engine if that helps:


    [​IMG]


    So if i don't have SAI then its just a case of putting a T in the hose coming from the inlet manifold and running a new hose from the T the the top of the DV ?


    Now for my next stupid question....lol


    Where is the hose i need to tap into on the manifold?


    I tried to trace the pipe coming from the n249 but it goes straight into a metal pipe and losses me...lol


    Thanks again mate ;)
    #12
  14. Alex C
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    Alex C Well-Known Member

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    [Jun 14, 2011]
    do you have SAI...well from your pic i can't see the combination valve for the secondary air injection which I think is the shiny metal circle valve you can see in Wellys picture below. Its just below the black hockey puck valve on the right hand side of the engine bay

    [​IMG]

    so maybe you don't have SAI...but to make sure back to your engine bay...

    [​IMG]

    your dipstick, in front of that there is a black metal plate, bolted to the underside of that black metal plate is the N249 valve and all of its related pipe work. If you have SAI then there will also be the N112 valve on the underside of that plate. So remove that metal plate and check if you have an N112 valve hidden under there....or take a pic of it. TBH i think i can see a hint of SAI pipe work going on under there, but I'm no expert

    i have a question, the blue hose coming of the top of your DV, where is that going?
    #13
  15. A3 T
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    A3 T Lord Of The Rings

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    [Jun 15, 2011]

    I thought this was the n249 .....lol


    [​IMG]



    I've uploaded some more pics here so you can click them and make them big:


    http://www.use.com/0e338201a46238eac844


    The blue hose is for my boost gauge ;)
    #14
  16. Alex C
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    Alex C Well-Known Member

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    [Jun 15, 2011]
    the bit you have circled is the vacuum reservoir, the N249 pipe work is underneath the black metal plate where your dipstick is. S3's are different as they have the vacuum reservoir and all of the N249 pipework sitting on top of the engine


    [​IMG]

    you can see some of the N249 pipework sticking out beneath the metal plate (the one with the sticker on it) in your pic above

    [​IMG]


    I think the ribbed piping with the mini blue cone filter on the end is for your SAI. It looks like somebody removed the standard airbox and therefore they have had to add a mini filter to your SAI air feed. The standard setup is that your SAI and your TIP share the same panel filter in the OE airbox.

    ...your combi valve must be hidden from view somewhere...under your breather hoses and TIP maybe. That'll be where the other ribbed pipe is going...
    Last edited: Jun 15, 2011
    #15
  17. A3 T
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    A3 T Lord Of The Rings

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    [Jun 16, 2011]
    I found another good guide here: Guide to removing / bypassing the N249 valve.


    But it seems that every guide i find says to mess about with the fpr :(


    I thought the bypass was a simple case of connecting a new hose between two parts and removing everything in-between .......lol


    I don't know if i should attempt this now as there seem more to it with the aum engine :(
    #16
  18. Syvo
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    Syvo IF IN DOUBT GO FLAT OUT

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    [Jun 16, 2011]
    that guide seems easy to follow just use one of the vac feeds under the inlet instead of the fpr i know on mine i have 1 behind the dip stick one to the right of that that is free then another one or two for the fpr and n249 orginal set up. will be doing mine next weekend so will fix a guide together and post it up
    #17
  19. Alex C
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    Alex C Well-Known Member

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    [Jun 16, 2011]
    yeah as paul said. Where he has taken the feed of the inlet manifold put a T piece in there so it can feed the DV and N112 valve instead of T'ing into the FPR line to feed the DV. Im not sure how necessary that one way valve is between the inlet manifold and N112 that he has in his guide, im not sure if Welly left a one way valve in there or not...
    #18
  20. Syvo
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    Syvo IF IN DOUBT GO FLAT OUT

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    [Jun 16, 2011]
    i will leave mine in as had fun and games last time with the 1 way valve for the brakes when did the oil catch can put stupid thing on wrong way lmao
    #19
  21. A3 T
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    A3 T Lord Of The Rings

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    [Jun 16, 2011]
    That would be good mate :)

    I think it would go down well on here because this thread seems to be getting a lot of hits buy not many replies, so it probably people thinking i made a guide.....lol




    I think the thing that gets me confused with the guide i posted up is......

    I'm with him up to the “copy what I've done” part of the guide but then at the end of the guide he says:


    “Once all this has been done all you need to do is give the DV another Vacuum feed. The easiest way to do this is to replace the braided line going from the bottom of the inlet manifold to the Fuel pressure regulator with a new tube that has a T piece in it. And then from the T piece run a vacuum tube straight to the top of your DV. You will see in my picture below that i have two T pieces in this Vacuum line. This is because i am running a boost gauge from here aswel. “


    I thought this last part was how you do the bypass by tapping in to the fpr so what was the point in all the other stuff ......lol
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  22. Alex C
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    Alex C Well-Known Member

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    [Jun 16, 2011]
    when he did the n249 bypass it also involved him removing the standard N112 (SAI) pipe work so all of the other stuff was replacing/simplifying that pipework first, and then he did his DV pipework (N249 bypass). But, he T'd his vacuum line for the DV into the FPR line which is not advisable.
    #21
  23. Syvo
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    Syvo IF IN DOUBT GO FLAT OUT

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    [Jun 16, 2011]
    as above the picture shows how he changed all the piping between the n112 and the n249 then ran the n112 to the underside of the inlet where the orginal went from the one way valve then from the n249 he tapped into the fpr you would need to not tap into the fpr and use another existing nipple under the inlet and connect the pipe from the n249 into this then tee off to the dv.

    i currently have my boost guage in the fpr but ive not cut it just put a tee at the top so can reconect the fpr when i do this it was a temporary thing to get the boost guage working using the fpr.

    done a quick sketch in paint (looks like a kids drawings please excuse)
    [​IMG]
    #22
  24. Syvo
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    Syvo IF IN DOUBT GO FLAT OUT

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  25. Syvo
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    Syvo IF IN DOUBT GO FLAT OUT

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    [Jun 16, 2011]
    this is what will appear from under the car if you tap into the fpr when doing the n249 you have been warned :asskicking:
    #24
  26. Alex C
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    Alex C Well-Known Member

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    [Jun 16, 2011]
    ....after the N249 bypass there is absolutley no pipework going to the N249 valve, nothing. Just the electrical connection
    #25
  27. 666markyboy
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    666markyboy Well-Known Member

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    [Jun 16, 2011]
    When i did mine i noticed the boost guage is T'd into the FPR line is this ok ??? or should i take it from somewhere else ???
    #26
  28. superkarl
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    superkarl MAN OF STEEL

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    [Jun 16, 2011]
    to avoid any potential problems with the fuel pressure reg its advised to take a boost gauge off the dv pipe. minimises any leaks or problems on the fpr which could at worst, mean running lean, which aint good at all.
    #27
  29. A3 T
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    A3 T Lord Of The Rings

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    [Jun 16, 2011]
    TBH... i think ill get about 4 meters of 4mm silicone hose and wait for paul syverson’s guide........lol


    I just know ill end up getting stuck half way through it and wont remember how to put it back the way it was.....lol
    #28
  30. Syvo
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    Syvo IF IN DOUBT GO FLAT OUT

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    [Jun 24, 2011]
    done and dusted will get the guide sorted out monday as left lead for phone in work.

    you will only need 2m of 4mm silicone pipe
    1 tee piece
    and a big swear tin the old clips for the pipes are a pita but got them all off and sorted it all out the other guide from the vw site makes it look harder than it is if i wasnt doing a guide and the clips were easy get off would say 30mins to do it probs less.
    #29
  31. A3 T
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    A3 T Lord Of The Rings

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    [Jun 24, 2011]

    I thought you was going to be doing this saturday/sunday....lol


    Does the car feel any different ?


    Yeah those clips are a right pain in the a*s, When i changed my thermostat i noticed that the braded hose going to the plated holing the n249 was almost split. and i had to get one of them clips off to change it.....lol


    I think ill be doing this the day you post up the guide :)
    #30
  32. nixy
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    nixy Member

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    [Sep 22, 2011]
    I sooo need to do this aswell but getting confused lol! Will just attack it and see what happens
    #31
  33. A3 T
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    A3 T Lord Of The Rings

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    [Sep 22, 2011]
    #32
  34. nixy
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    nixy Member

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    [Sep 25, 2011]
    to be fair ive not really looked at my car etc yet as not had time lol!! Will use those uides and i should work itout lol Cheers
    #33
  35. stevie e
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    stevie e Member

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    [Oct 15, 2011]
    worked for me , got an aum
    #34
  36. kelk11
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    kelk11 Member

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    [Oct 24, 2011]
    I have a bam engine and I have just run a pipe from the inlet mani to top of DV, test drove no problems and it seems to have cured a boost leak, upon removing the left over pipe work there seems to be one pipe leading into another pipe near the fuel rail. do i just remove this?
    #35
  37. Alex C
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    Alex C Well-Known Member

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    [Oct 24, 2011]
    you got any pictures?
    #36
  38. kelk11
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    kelk11 Member

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    [Oct 24, 2011]
    I went outside to get a pic, all sorted i was just being thick.
    #37

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