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    Thread: Bypassing the N249 - An Easier Approach

    1. 04-27-2004 07:37 PM #1
      I just finished road testing my car after bypassing the N249, in a much more direct and "clean" method than some of the ones I've seen suggested. It works great, partial throttle is MUCH smoother and predictable - no jerky boost.

      All I did was this:

      1. Trace the path of the top (actuator) hose from the DV. It goes to a metal tube that runs along the block, then to another rubber hose, then underneath the intake manifold to the N249.

      2. Remove the hose that connects the tube to the N249, at the side closer to the N249. There is a reusable clamp, just pinch it with pliers and pull the tube off.

      3. Cap the tube to the N249 with a rubber hose cap (available at Auotzone, etc.) and clamp it on there with a hose clamp.

      4. Tapinto the FPR vacuum/boost line, which is RIGHT NEXT to the hose you just disconnected. It's the thinner braided hose that goes to the FPR.

      5. Using a 3/16" x 3/16" x 3/16" T fitting, connect the newly disconnected N249 hose to the T.

      Voila. Instant, clean bypass. Works like a charm, looks stock.


    2. 04-27-2004 07:40 PM #2
      All you need to do this is:

      1. 2 hose clamps
      2. 3/16" T fitting (plastic works fine)
      3. 5/16" rubber cap


    3. Member Seanathan's Avatar
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      04-27-2004 07:44 PM #3
      very nice man. for now I was just going to cap of the line from the dv valve, and run a new one.

    4. 04-27-2004 07:53 PM #4
      always good to see useful info on this forum

    5. 04-27-2004 07:53 PM #5

      I Just did it this way myself. Except I tee'd into the other Vac line right next to the FPR line on the underside of the manifold. I already tee'd the FPR line once for my boost gauge. Also, I used a ss bolt to plug the hose instead of capping it at the N249. Boost is much more predictable at part throttle.


    6. 04-27-2004 08:00 PM #6
      Quote, originally posted by enginerd »

      I Just did it this way myself. Except I tee'd into the other Vac line right next to the FPR line on the underside of the manifold. I already tee'd the FPR line once for my boost gauge. Also, I used a ss bolt to plug the hose instead of capping it at the N249. Boost is much more predictable at part throttle.

      i took this route as well... works just fine

    7. Member 1.8tizzle's Avatar
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      04-27-2004 09:39 PM #7
      I did it a more ghetto, easy way. The black vaccum box on the valve cover....... i unbolted it, and followed that line to where its plugged. Pulled that hose, and just put a cap over the tube where the line went to. Works fine for me.

    8. 04-27-2004 10:49 PM #8
      Is this another possible solution to upgrading the N75 when surging is a problem? I'm still learning about my motor and saving for a VAG-COM setup so I don't want to do anything that will throw codes or cause more problems.

    9. 04-28-2004 12:13 AM #9
      My car surges also, im running garrett software. It only surges at WOT in a high gear. Is this a remidy for my problem, Sorry im not the smartest at engines

    10. 04-28-2004 10:11 AM #10
      Quote, originally posted by 1.8tizzle »
      I did it a more ghetto, easy way. The black vaccum box on the valve cover....... i unbolted it, and followed that line to where its plugged. Pulled that hose, and just put a cap over the tube where the line went to. Works fine for me.

      This doesn't actually bypass the N249 - the electronic valve still mediates what the DV sees. It helps because the valve can no longer introduce vacuum to the mix.

      What I did is plug the DV directly into the intake manifold. The DV now sees exactly what is in the manifold, there's nothing inbetween.

      There may not be any practical difference - but I like knowing that the DV actuation is directly from the manifold.


    11. 04-28-2004 10:12 AM #11
      Quote, originally posted by Mk4Jettaboy »
      My car surges also, im running garrett software. It only surges at WOT in a high gear. Is this a remidy for my problem, Sorry im not the smartest at engines

      Try bypassing the N249 as I suggested. It may help, it may not, but it's a very cheap mod that you should do regardless.


    12. 04-28-2004 10:19 AM #12
      Quote, originally posted by dbrowne1 »

      This doesn't actually bypass the N249 - the electronic valve still mediates what the DV sees. It helps because the valve can no longer introduce vacuum to the mix.

      What I did is plug the DV directly into the intake manifold. The DV now sees exactly what is in the manifold, there's nothing inbetween.

      There may not be any practical difference - but I like knowing that the DV actuation is directly from the manifold.

      I did this and now have severe fluttering of my hyperboost DV. Cleaned and lubed it and that didn't help. I believe that the n249 also serves to assist in slamming the DV open as fast as possible via the extra vac in the black canister. I was not having any problems with the N249 opening the DV when I didn't want it to so I may be putting the canister back on and reconnecting everthing in a stock manner.


    13. 04-28-2004 10:54 AM #13
      Quote, originally posted by GTIMOLA »

      I did this and now have severe fluttering of my hyperboost DV. Cleaned and lubed it and that didn't help. I believe that the n249 also serves to assist in slamming the DV open as fast as possible via the extra vac in the black canister. I was not having any problems with the N249 opening the DV when I didn't want it to so I may be putting the canister back on and reconnecting everthing in a stock manner.

      The problem here is your hyperboost DV and too stiff of a spring. With a Forge valve, mine does the same thing. With the stock valve it works like a champ.

      Have you tried reversing your DV?


    14. Member JettaRed's Avatar
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      04-28-2004 11:03 AM #14
      Is the sole purpose to eliminate surging or fluttering at high boost levels (>15 psi)?
      2004 Audi TT225 GIAC, DevilsOwn W/M, Modshack MOFO & VTDA, 42DD 3" DP, Neuspeed 19mm Rear Sway, Haldex Blue
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    15. 04-28-2004 11:03 AM #15
      I figured that this was the problem. Unfortunately, the stock dv failed and I would really like to use the Hyperboost. I wonder if there is a way that I could modify the current spring or get a softer spring.

    16. 04-28-2004 11:04 AM #16
      Quote, originally posted by GTIMOLA »

      I did this and now have severe fluttering of my hyperboost DV. Cleaned and lubed it and that didn't help. I believe that the n249 also serves to assist in slamming the DV open as fast as possible via the extra vac in the black canister. I was not having any problems with the N249 opening the DV when I didn't want it to so I may be putting the canister back on and reconnecting everthing in a stock manner.

      I have an older Forge 006 valve (it's almost 4 years old) and it works fine with the bypassed setup. Zero flutter. I'm holding 25-27psi in the lower rpms, 20psi at 5K, using an MBC.

      If you had better performance with the N249/vac cannister then by all means go back to using it. Results are what matter. One thing that's nice about the setup I suggest is that it is easily reversible. The only "permanent" change is cutting the fpr line, and that's easily fixed with a plug on the T or a plastic hose connector.


    17. 04-28-2004 11:05 AM #17
      Quote, originally posted by JettaRed »
      Is the sole purpose to eliminate surging or fluttering at high boost levels (>15 psi)?

      Main purpose is to reduce flutter and resulting jerky boost at partial throttle, between 0 and 5psi of boost, where the N249 seems to get confused and can make your throttle very sensitive and jerky. It worked well for me.


    18. Member JettaRed's Avatar
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      04-28-2004 11:13 AM #18
      It amazes me how every car is soooo different.
      2004 Audi TT225 GIAC, DevilsOwn W/M, Modshack MOFO & VTDA, 42DD 3" DP, Neuspeed 19mm Rear Sway, Haldex Blue
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    19. 04-28-2004 11:23 AM #19
      that is a great way to do it, keeps it looking stock since you are changing an area normally hidden by engine covers...

    20. Member coolvdub's Avatar
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      05-01-2004 03:27 PM #20
      I looked at my car an '02 Jetta and the small braided line goes to the Combi valve not the FPR. So my question is, did you actually tap into the FPR line which is braided also and very short or the line feeding the Combi valve, also braided, but longer and right next to the line that feeds the N249 valve.
      Don

      CANCER SUCKS but KAISER SUCKS MORE/But so far I kicked it's ASS

    21. 05-02-2004 11:29 AM #21
      Quote, originally posted by coolvdub »
      I looked at my car an '02 Jetta and the small braided line goes to the Combi valve not the FPR. So my question is, did you actually tap into the FPR line which is braided also and very short or the line feeding the Combi valve, also braided, but longer and right next to the line that feeds the N249 valve.

      if you are talking from the intake minifold, its the same vaccum/boost source, so it doesn't matter...

      but i would use the FPR line.


    22. Member coolvdub's Avatar
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      05-02-2004 01:02 PM #22
      Okay, thanks for the advice. I will do exactly that.
      Don

      CANCER SUCKS but KAISER SUCKS MORE/But so far I kicked it's ASS

    23. Member turbotazzy's Avatar
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      05-08-2004 07:39 PM #23
      Okay, I just did this mod. Partial throttle is improved bigtime over what it was before. A couple times, I punched it and backed off the throttle. I had the lurch a couple of times but it went away after more driving.

      However, I think I'm still getting a DV flutter. I have the 710N valve and it sounds like the DV is opening and closing rapidly at partial throttle while it hisses. Ssss-sss-ss-ss-sssss-sss-sss! Lol! Would a MBC help or maybe an adjustable DV (GReddy Type S) so that I can play with the settings and try to adjust it?

      By the way, I tee'd into the fpr line. It was a b*tch to get to! 5 minute job? Yeah... okay.


      Modified by turbotazzy at 4:40 PM 5-8-2004

      Frantz Tassy
      Miami, Florida
      2002 VW GTI 337

    24. 05-08-2004 08:02 PM #24
      to get to? The fpr line is like right there, it should take 2 minutes to cut it and put a t on it

    25. Member turbotazzy's Avatar
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      05-09-2004 04:09 AM #25
      Maybe I used the wrong T. I used3/16" x 3/16" x 3/16". It didn't go on very easily. That combined with what I found to be tight quarters (couldn't get a firm grip on it to push the hose on the t) didn't make it a 2-minute job... for me. That fpr line is short!!!
      Frantz Tassy
      Miami, Florida
      2002 VW GTI 337

    26. 05-12-2004 03:17 PM #26
      some picture of what you are talking? because i plan to do it, i have to try everything to solve my problem! thanks

    27. 05-12-2004 03:44 PM #27
      Quote, originally posted by turbotazzy »

      By the way, I tee'd into the fpr line. It was a b*tch to get to! 5 minute job? Yeah... okay.

      I'm sorry, but a one-armed ape with downs syndrome and a butter knife could do this in 5 minutes. The line is practically staring you in the face if you are looking down at the point where you detach the hose between the DV and the N249.

      The 3/16" T fitting is tight, but tight is good. It means it won't come loose, even if you don't use clamps on it.


      Modified by dbrowne1 at 12:45 PM 5-12-2004


    28. 05-12-2004 04:20 PM #28
      Any reason for those of us unchipped (as yet) to do this mod? I don't have any noticeable surging or other problems.

      P.S. I typed this with one hand, using my butter knife.


    29. Member turbotazzy's Avatar
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      05-12-2004 08:53 PM #29
      Quote, originally posted by dbrowne1 »

      The line is practically staring you in the face if you are looking down at the point where you detach the hose between the DV and the N249.
      Modified by dbrowne1 at 12:45 PM 5-12-2004

      Just because it's staring me right in the face doesn't mean it's easy to work with. It took 1 minute to cut the line and put the tee on one end of the hose but to put the other tee on was a pain to me. You can't tell me you can put two hands in there without a problem. The fpr line is very short!

      My setup doesn't look like this:

      http://www.aurealanrealms.org/~tjboyer/PIPING.jpg

      If it did, it would be much easier... but whatever. I'm 90% surge-free now. Thanks for the write-up. No thanks for the sarcasm.

      Frantz Tassy
      Miami, Florida
      2002 VW GTI 337

    30. 05-12-2004 09:32 PM #30
      be smarter then what you are working on. if you can't get it with the hose on, remove it, you can also turn the FPR to the side to allow you better access to the Vac line. this is a very simple thing to do.
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    31. 05-13-2004 08:55 AM #31
      Quote, originally posted by turbotazzy »

      If it did, it would be much easier... but whatever. I'm 90% surge-free now. Thanks for the write-up. No thanks for the sarcasm.

      Well, you're welcome for the writeup. That's why I put it here.

      Please note that NOWHERE in the writeup did I say that is was a "five minute job," a term that you injected and which you sarcastically commented upon in your entirely unnecessary and unsolicited response. Also note that I have not one, but TWO 3/16" T fittings in my "short" fpr line. That's probably because it isn't really that short at all.


    32. 05-13-2004 11:12 AM #32
      awesome, thanks for the write up dbrowne. my part throttle is horrible.. hopefully this will improve it.

    33. Member turbotazzy's Avatar
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      05-13-2004 02:54 PM #33
      My comment was never meant sarcastically and it wasn't directed towards you. Okay, I'll stop this unnecessary bickering and keep this thread on topic.

      Question: How do I stop the lurching I get when I let off the throttle slowly? Is this a DV issue? This doesn't happen when I let off quickly. I've read that the DV opens when you're on boost and closes when you let off. I have the 710N valve so it's non-adjustable. Would an adjustable DV help resolve this issue? I thought bypassing the N249 would help but it hasn't.

      Thanks in advance.

      Frantz Tassy
      Miami, Florida
      2002 VW GTI 337

    34. 05-13-2004 03:01 PM #34
      Would this mod be any good with stock engine?

    35. 05-13-2004 03:37 PM #35
      Quote, originally posted by guywhoisjustin »
      Would this mod be any good with stock engine?

      It is meant to solve a specific issue (partial throttle sensitivity) which is not usually an issue in stock cars.


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