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N249 bypass.. questions about N112 and SAI, help please (welly lol)

Discussion in 'A3/S3 Forum (8L Chassis)' started by coyle, Jan 21, 2011.

  1. coyle

    coyle From Show... to GO

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    So, had a go at the N249 bypass following wellys guide..

    encountered a few issues..

    firstly, i snapped the valve off the N112, exactly the same as welly (i think i followed his guide too closely haha)

    So basically, I've ran a piece of silicone hose from the inlet mani to the DV, and another piece to the FRP

    I know i need to "T" in to the pipe from the inlet mani to the DV and run that to the N112, and then the other valve of the N112 up to the SAI, but due to it snapping, ive completely left it out (its still plugged in) but this also means the SAI has a valve which isn't being used, which should be connected.

    So I drove from my mates, 30miles away, where i did the removal, and the car is running perfect, it feels a lot more responsive than before.
    So my question is, so i need to re-plumb the N112 back in to the system? as effectively i have also taken the SAI out of the system too which i guess isn't good?

    why is the N112 needed? and what does the SAI do? as currently im not using either

    Cheers
    Jon
     
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  3. Audi2ptzero

    Audi2ptzero Member

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    The 2 valves just control the BPV and SAI. So if you deleted the SAI and ran a hose to the BPV you dont need either of those control valves.

    SAI only comes on while the engine is cold and is really only there for emmissions to add air to the rich exhaust gas and increase the flow.
     
  4. coyle

    coyle From Show... to GO

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    sorry dude, whats the BPV? im stupid
     
  5. Alex C

    Alex C Well-Known Member
    VCDS Map User Audi S3

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    yeah, me too, whats the BPV? By-pass valve?

    I think SAI dilutes the exhuast gasses when the engine is cold to improve emmisions and help the CAT.....I think
     
  6. Dani_B19

    Dani_B19 Audi-sports own special child.

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    The SAI blows air into the engine/cat's on warm up for emissons etc, its stops running after several minutes of start up.
     
  7. <tuffty/>

    <tuffty/> Badger 5 Edition...Its all about the flow...
    Staff Member Moderator Audi S3

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    Whatever you do though you should leave them electrically connected... Welly will no doubt chip in with an explanation of this...

    <tuffty/>
     
  8. coyle

    coyle From Show... to GO

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    so do i not need to connect the hose which is currently from the DV to the inlet mani down to the N112 valve?

    and I dont need to run a hose from the other size of the N112 to the SAI?

    should i at least put a blank or something on top of the SAI? as currently its just a valve/tap with nothing on it at all?
     
  9. coyle

    coyle From Show... to GO

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    yeh i have done tuffty, although the N112 has no hoses attached to it, it is still electrically connected, as is the N249
     
  10. <tuffty/>

    <tuffty/> Badger 5 Edition...Its all about the flow...
    Staff Member Moderator Audi S3

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  11. Audi2ptzero

    Audi2ptzero Member

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    If you are no longer using the SAI you can just remove the valve that is bolted to the back of the head and just replace it with a block off plate.

    [​IMG]
     
  12. coyle

    coyle From Show... to GO

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    i think, because it's there, i'll try to include it, i'll get a "T" piece from the inlet mani to DV, to take to the N112, then the other N112 hose up to the SAI,

    i'll either try and repair the N112 the same way Welly did, or try to source a new N112. any ideas where i'd get one from? and how much it would be?
     
  13. finesse

    finesse Active Member
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  14. badger5

    badger5 www.badger5.co.uk
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    if you run with the solenoids disconnected, your lambda adaption is not going to work = bad
     
  15. coyle

    coyle From Show... to GO

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    But as it is all my solenoids are connected electrically
     
  16. badger5

    badger5 www.badger5.co.uk
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    good.
     
  17. MintyS3

    MintyS3 Works 60% the time, Everytime.

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    Question. Ive done the n249 bypass and left the solenoid connected but ive noticed that vagcom picks up on the n249 valve being faulty. Will this have the same effect as not having the solenoid connected and should I pick up a new solenoid to plug in place to clear the code?
     
  18. badger5

    badger5 www.badger5.co.uk
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    "mechanical problem check DV" type fault?

    bypassed correctly? working dv?
     
  19. MintyS3

    MintyS3 Works 60% the time, Everytime.

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    I honestly cant remember the exact error. Ive been meaning to take another look but it did specifically mention the n249, infact my dv stopped working originally which prompted me to do the bypass. The dv works fine now so setup correctly.
     
  20. Welly

    Welly VX220 SC Driver :)

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    Yeah - what he said....

    Leaving the solenoids unplugged will stop adaptive fuelling completely. Not only do you HAMMER through fuel on idle and cruise, but you also get a nice failure ticket at the MOT place...

    Screw the N249 back to the metal plate, plug in and forget about it. Then remove the entire SAI system as the thing is a waste of space as well.

    I was really chuffed off when I snapped the stub on the N112, but to be fair, it simply isn't important.
     
  21. Welly

    Welly VX220 SC Driver :)

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    PS. Sorry for late response - didn't come on here at all over the weekend :(. Lots of things going on, none car related.
     
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  23. coyle

    coyle From Show... to GO

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    So how do i remove the sai completely?
    I looked at the guide and it looked very complicated! Ive looked at the SAI and one of the coregated plastic pipes which runs from underneath it is snapped, it looks like it's gone brittle with age.

    Before i get carried away.. The SAI is the silver meta circular parts on the right of the engine isnt it?
     
  24. Welly

    Welly VX220 SC Driver :)

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    Yes, but there is more to it than that. For now you can block off the pipe that originally went to the nipple you snapped off the N112.

    You will need to get either a Forge or IE blanking plate to cap the hole in the side of the head.

    The combi valve (silver bit on the side of the head) is only one part of a bigger system. The SAI pump lived down underneath the oil filter and that needs to be removed as well.

    A bit of a pain to get out, but once doen, it also has the added benefit of making oil filter changes a sh*t load easier.

    There is a guide to SAI removal here: http://www.audi-sport.net/vb/a3-s3-forum-8l-chassis/88299-sai-removal-guide.html
     
  25. coyle

    coyle From Show... to GO

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    welly, the bit you snapped (same bit i snapped) is that the one which is to go the the T on the DV to inlet mani?
    and the other one which didnt snap is to the SAI right?
     
  26. Welly

    Welly VX220 SC Driver :)

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    If it's snapped dude, you basically run a single length of vac hose from the inlet manifold to the DV. The pipe to the SAI combi valve comes from the N112.
     
  27. Welly

    Welly VX220 SC Driver :)

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    Having re-read that (too many glasses of vino), Yes, that's right.
     
  28. coyle

    coyle From Show... to GO

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    haha, i read your 1st post and thought.. maybe il ask in the morning..
    but yeh all good lol, i plastic welded a valve on, went ot but silicone hose on.. snap lol
    but welded it on againg (with the hose attached first just incase)
     
  29. Welly

    Welly VX220 SC Driver :)

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    I wouldn't worry too much dude, it won't affect the car's running. At worst it will give you an 'Incorrect flow' fault code.
     
  30. Welly

    Welly VX220 SC Driver :)

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    Also, add some epoxy resin around the break for added strength.
     
  31. coyle

    coyle From Show... to GO

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    where will i get that from in the morning halfords? or will b&q do something similar? i was going to put a layer of silicone over it all to make sure theres no air leaks
     
  32. Welly

    Welly VX220 SC Driver :)

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    Sorry, epoxy resin is Araldite or similar. You should be able to get that from next to anywhere.
     
  33. a3evotg

    a3evotg New Member

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    Ive snapped the connection off the n112 doin this, so did away with it and the SAI and the piping and just ran a hose from the inlet to the top of the dumpvalve with the one way valve as per the diagram above, is this ok?it seems it jus seems to take a while to build boost pressure up, but no fault codes as ive left he sai, the 112 and the 249 still plugged on
     

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