# Bypassing the n249



## 00B5A4 (Oct 28, 2011)

does this increase boost, or just how reactive/sensative it is?


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## Twopnt016v (Jul 5, 2009)

It makes the diverter valve more responsive and will make the mid range smoother. Any surging issue will typically go away after bypassing the n249. The n249 controls the diverter valve so it will bleed boost off at times that you don't want to bleed off and that is how surging comes into play. Once you bypass the n249 and run your diverter valve vacuum hose off of the intake manifold the dv will work much better. and won't bleed off boost unnecessarily. I have this done to my car:thumbup:


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## 00B5A4 (Oct 28, 2011)

Twopnt016v said:


> It makes the diverter valve more responsive and will make the mid range smoother. Any surging issue will typically go away after bypassing the n249. The n249 controls the diverter valve so it will bleed boost off at times that you don't want to bleed off and that is how surging comes into play. Once you bypass the n249 and run your diverter valve vacuum hose off of the intake manifold the dv will work much better. and won't bleed off boost unnecessarily. I have this done to my car:thumbup:


sweet! Best explanation yet that I've got/or read. So that means my car MUST be chipped then. Theres no sign of a DIODE mod and even if there was I don't think I would hold 18-20lbs even in 5th gear.

Thanks man!


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## Twopnt016v (Jul 5, 2009)

:thumbup:
No problem...
Your car would benefit from this even if it isn't chipped.
If it was chipped it might be more of a noticeable difference.
To bypass all you do is disconnect the vac lines at the n249...
Leave the n249 plugged in and will not get any fault codes...
Run a vac line from the intake manifold to diverter valve....
You can now remove the black box vacuum reservoir from the top of the valve cover above coil pack #3 and #4. :thumbup::thumbup:


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## LEBGTIMK4 (Sep 13, 2010)

remove the N249 valve and insert the connector with a 10w 330 Ohms resistor so you don't get any CEL, or a 10w 470 Ohms resistor will also work fine. I did to my car that ain't mapped yet and i felt the difference on the boost gauge!!


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## 00B5A4 (Oct 28, 2011)

Twopnt016v said:


> :thumbup:
> No problem...
> Your car would benefit from this even if it isn't chipped.
> If it was chipped it might be more of a noticeable difference.
> ...




Yeah I dsconnected all the van lines and capped the main constant vac source. Then DV to Inyake manifold. No CEL. 

Thanks guys for the tips!


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## Twopnt016v (Jul 5, 2009)

A stated above you can get a resistor and put it in the connector for the n249 or leaving it plugged does the same thing. Most people who just bypass the n249 just leave it plugged in since they are not removing the whole assembly where the n249 is located. If you were to remove the whole assembly with the vavle that runs the combi then the resistors are the way to go:thumbup:


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## 00B5A4 (Oct 28, 2011)

LEBGTIMK4 said:


> remove the N249 valve and insert the connector with a 10w 330 Ohms resistor so you don't get any CEL, or a 10w 470 Ohms resistor will also work fine. I did to my car that ain't mapped yet and i felt the difference on the boost gauge!!


I don't get a code or CEL when I delete the vac lines and leave the n249 connected. hmmm.


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## Twopnt016v (Jul 5, 2009)

00B5A4 said:


> I don't get a code or CEL when I delete the vac lines and leave the n249 connected. hmmm.


You get no codes because you followed my instructions...:laugh::laugh:
Leaving the valve plugged in does the same thing as a resistor. The resistor just tricks the car into thinking the valve is still there. :thumbup::beer:


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## LEBGTIMK4 (Sep 13, 2010)

Twopnt016v said:


> You get no codes because you followed my instructions...:laugh::laugh:


:thumbup: Looolllll I like this part....
:beer:


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## Twopnt016v (Jul 5, 2009)

LEBGTIMK4 said:


> :thumbup: Looolllll I like this part....
> :beer:


:thumbup::beer::thumbup::beer::thumbup::beer::laugh::laugh:


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## [email protected] (Jul 1, 2009)

I don't know how you guys can stand the drivability with the N249 gone. Absent the diverter valve control it provides, my car's part-throttle behavior had all the refinement of a Sherman tank.

My advice to the OP is: audition the mod with a BYPASS of the N249 first. Don't pull out all the hardware until you've felt what it's like. After a week of being lurched around, I restored the vacuum line off the N249 to the DV.


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## Twopnt016v (Jul 5, 2009)

[email protected] said:


> I don't know how you guys can stand the drivability with the N249 gone. Absent the diverter valve control it provides, my car's part-throttle behavior had all the refinement of a Sherman tank.
> 
> My advice to the OP is: audition the mod with a BYPASS of the N249 first. Don't pull out all the hardware until you've felt what it's like. After a week of being lurched around, I restored the vacuum line off the N249 to the DV.


Actually what you experienced is the antithesis of what we experience with this mod. All of our drivability, surging and part throttle issues get resolved with this mod...
Not sure what went wrong with yours Doug?....


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## LEBGTIMK4 (Sep 13, 2010)

[email protected] said:


> I don't know how you guys can stand the drivability with the N249 gone. Absent the diverter valve control it provides, my car's part-throttle behavior had all the refinement of a Sherman tank.
> 
> My advice to the OP is: audition the mod with a BYPASS of the N249 first. Don't pull out all the hardware until you've felt what it's like. After a week of being lurched around, I restored the vacuum line off the N249 to the DV.


At first you will feel the car lazy but once the ECU adapt to it, it will run fine. When I installed the K04-001 on my car and the boost Gauge and before bypassing the N249 to boost will spike at ~11psi the go to 9 then 10 then go down when reached the redline.
When I deleted the N249 the Car will boost to 11psi and hold on boost from 2500RPM till 5000RPM before starting going down till redline.


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## black wolfsburg 99 (May 7, 2005)

Ok, I literaly have my bracket fliped and ready to snip lines to see how this bypass feels but before I do it I just want to be clear on whats the easiest way to be able to reverse everything if I dont like it. Your saying all I have to do is disconnect the three lines going to the N249 and plug them and that is it? Other then running a vacum source to the diverter valve.


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## 00B5A4 (Oct 28, 2011)

black wolfsburg 99 said:


> Ok, I literaly have my bracket fliped and ready to snip lines to see how this bypass feels but before I do it I just want to be clear on whats the easiest way to be able to reverse everything if I dont like it. Your saying all I have to do is disconnect the three lines going to the N249 and plug them and that is it? Other then running a vacum source to the diverter valve.


No need to snip lines at all. Just unplug the constant vac source to the n249 and put the DV to the manifold. That is all:laugh: If you like it leave it and if you don't, plug everything back in.
I plugged my main constant with a little bolt and zip tied it.:thumb up:


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## 00B5A4 (Oct 28, 2011)

Did the bypass in the morning, drove it around a little bit, and when I went to go drive it around again at night, my car ran...AMAZING. :thumbup: N249 delete is the way to go.

Current set up: n249 delete, with a forge 007, and n75j, also chipped.


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## black wolfsburg 99 (May 7, 2005)

I had to drive it, so I put everything back together. Does anyone have a diagram to show me which one to disconnect and plug? I will be taking it appart again tommorow to look for the constant vacumm anyways but knowing which one upfront will help make things faster ofcourse. Thanks!


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## [email protected] (Jul 1, 2009)

Twopnt016v said:


> Actually what you experienced is the antithesis of what we experience with this mod. All of our drivability, surging and part throttle issues get resolved with this mod...
> Not sure what went wrong with yours Doug?....





00B5A4 said:


> Did the bypass in the morning, drove it around a little bit, and when I went to go drive it around again at night, my car ran...AMAZING. :thumbup: N249 delete is the way to go.
> 
> Current set up: n249 delete, with a forge 007, and n75j, also chipped.


What the? You know, I must have done something wrong. Seriously, my car did not like that mod. Interesting....


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## black wolfsburg 99 (May 7, 2005)

Found a nice diagram here
http://forums.vwvortex.com/showthre...imate-SAI-N249-PCV-EVAP-Delete&highlight=n249


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## radrabt (Oct 13, 2008)

I did this today. Iv uad boost leak problems that i didnt care to track down for about a year now and was running 10-115 psi. Then a kid at work bought a 07 gti dsg that someone traded in. I cant let this kid think hes top dog lol. So, i made a boost leak tester and found my first leak at the vac line from the manifold to fpr. This also explains my guage acting funny, i thought it was a faulty and inacurate guage. Leak tested again and found that i had broken a hard line coming off of the n249 and it was leaking boost. I snipped all 4 lines off and unplugged it. Ran a vac line from bottom of manifold to dv. Plugged some bolts in all the combi valve lines (dunno if it makes a diff or not)until i get a block off plate and do the combi valve delete. Then the dv was leating where it goes into the TIP so i tightened that clamp. Went for a test drive and BAM! 23 psiiiiiii!!!!! 

It drove great and felt extreemly smooth but it doesnt feel as strong as i remember it befor the leaks. Maybe the.ecu needs some time to learn or something, if it even does that.


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## radrabt (Oct 13, 2008)

black wolfsburg 99 said:


> Found a nice diagram here
> http://forums.vwvortex.com/showthre...imate-SAI-N249-PCV-EVAP-Delete&highlight=n249


I used that thread as a guide. Im going to do the pcv thing next since i ghetto rigged mine as a temp setup and ended up leaving it for about 2 years now. Anyone know what the hockey puck does and what getting rid of it is suppoed to do or not do? I dont thnk im going to remove the evap stuff though.


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## Scigano (Mar 10, 2011)

00B5A4 said:


> Did the bypass in the morning, drove it around a little bit, and when I went to go drive it around again at night, my car ran...AMAZING. :thumbup: N249 delete is the way to go.
> 
> Current set up: n249 delete, with a forge 007, and n75j, also chipped.


I have all of this, save for the N75J valve (I got an E-revision for when my C failed). I know that if certain chips that spike hard and react poorly w/ some cars, you can experience full throttle surging (as the base N75 struggles with the Kung-Fu chops to the neck). The N75J has been used for curing full-throttle surging issues, but does it do anything for part-throttle surging (like build boost linearly)?

I have bypassed my N249 and have GIAC on my K03 ATC engine narrowband ECU.


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## black wolfsburg 99 (May 7, 2005)

So if I pull the vacum line that I marked in red and I cap off the hose and manifold it will bypass the N249? If so, wont it also bypass the SAI valve? I know I have to run the vac source to the DV but thats no problem at all.



Uploaded with ImageShack.us


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## 00B5A4 (Oct 28, 2011)

radrabt said:


> found my first leak at the vac line from the manifold to fpr. This also explains my guage acting funny, i thought it was a faulty and inacurate guage.


I think I have this problem, how do you do a Vac test??


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## 00B5A4 (Oct 28, 2011)

Scigano said:


> I have all of this, save for the N75J valve (I got an E-revision for when my C failed). I know that if certain chips that spike hard and react poorly w/ some cars, you can experience full throttle surging (as the base N75 struggles with the Kung-Fu chops to the neck). The N75J has been used for curing full-throttle surging issues, but does it do anything for part-throttle surging (like build boost linearly)?
> 
> I have bypassed my N249 and have GIAC on my K03 ATC engine narrowband ECU.


I have ZERO surging problems, but I think I may have a vac leak coming from my FPR, I'll check it out tomorrow. I can hear that slight leak and it get real loud when I put my ear up to the FPR.


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## LEBGTIMK4 (Sep 13, 2010)

00B5A4 said:


> I think I have this problem, how do you do a Vac test??


Boost Gauge is the way to go. If you have a Boost-Vaccum Gauge. in the Morning when the car is cold turn it on and watch the Vaccum reading it should be 15 to 10 in HG if it is btw 30 to 20(included) it means you have a vac leak.

Hope it helps,
Fouad


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## 00B5A4 (Oct 28, 2011)

LEBGTIMK4 said:


> Boost Gauge is the way to go. If you have a Boost-Vaccum Gauge. in the Morning when the car is cold turn it on and watch the Vaccum reading it should be 15 to 10 in HG if it is btw 30 to 20(included) it means you have a vac leak.
> 
> Hope it helps,
> Fouad


yeah usually my car in the morning idles around 10ish, then after a few minutes after I let it warm up, it goes to about 21-22 hg.

Sometimes if I let it idle for a long amount of time my boost gauge jumps to 10hg then fluctuates, then my car will die if I don't hit the gas to rev the engine. 

such a weird problem I have randomly.


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## Twopnt016v (Jul 5, 2009)

00B5A4 said:


> I think I have this problem, how do you do a Vac test??


You want to do a pressure test to find leaks....
Follow this....

http://forums.vwvortex.com/showthread.php?2692757


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## radrabt (Oct 13, 2008)

After i found my boost leaks my vac went frok 20 to 25 and it idles better than befor. It used to shut off randomly also.


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## 00B5A4 (Oct 28, 2011)

Twopnt016v said:


> You want to do a pressure test to find leaks....
> Follow this....
> 
> http://forums.vwvortex.com/showthread.php?2692757




Im am going to have to do this today!! Thanks man:thumbup:


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## Scigano (Mar 10, 2011)

radrabt said:


> After i found my boost leaks my vac went frok 20 to 25 and it idles better than befor. It used to shut off randomly also.


25 in. Hg.? What's healthy vacuum supposed to be on a motor w/o leaks? I thought around 18-19 in.Hg. at idle and just over 20 in. Hg. in in-gear deceleration.


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## radrabt (Oct 13, 2008)

Not sure what its supposed to be but this evening my car idled at 21-22ish. Decelration was about 25 like you said. My guage could be off though cause when the car is off, the needle will sometimes sit right under 0.


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## LEBGTIMK4 (Sep 13, 2010)

20 - 21 hg on iddle and 25 -27 on gear is ok


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## 00B5A4 (Oct 28, 2011)

radrabt said:


> Not sure what its supposed to be but this evening my car idled at 21-22ish. Decelration was about 25 like you said. My guage could be off though cause when the car is off, the needle will sometimes sit right under 0.


20-22 is nice idle.


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## BMAN (Jun 9, 1999)

I'm about to do this to my car and need a little help. The N249 has 3 hoses on it which one do I plug? Where on the manifold do I hook the DV to? Thanks


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## Scigano (Mar 10, 2011)

BMAN said:


> I'm about to do this to my car and need a little help. The N249 has 3 hoses on it which one do I plug? Where on the manifold do I hook the DV to? Thanks


 I think you just stick a bolt in the line that use to go to the top of your Diverter Valve and then you can Tee into the line for your Fuel Pressure Regulator. (if so you choose)


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## 00B5A4 (Oct 28, 2011)

BMAN said:


> I'm about to do this to my car and need a little help. The N249 has 3 hoses on it which one do I plug? Where on the manifold do I hook the DV to? Thanks


 
The n249 has 3 ports to it (facing the engine) 2 on the left and one on the right. the one on the right is where the factory connects it to the intake manifold(front). 

On the left: a nipple points out towards the front of the engine, thats where the DV connects to. The other nipple(points to the left) connects to some type vacuum hose that connects to the n211 i believe. 

There are 2 ways: 
#1: run the DV straight to the intake manifold, Then with the vacuum hose that was connected to the manifold, connect that to where the DV was previously connect. Done. 

#2: Put a screw in the vacuum line that comes of the n211 connection(the constant vacuum source). delete the other hoses off of the n249 completely, and run a hose from DV to manifold. done. 

hope this helped. good luck, and let me know how this goes for you


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## Scigano (Mar 10, 2011)

See ^^^ I told you to start your own thread for your own thing. You've already corrected me :facepalm:.


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## BMAN (Jun 9, 1999)

Thanks for your help guys. So I run a vacuum hose from the DV to manifold. Pull the hose off the N249 valve on the right that supplies vacuum and run that hose to the hose that use to plug into the DV? 

I also read you can just cap off the hose pulled from the Valve?


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## [email protected] (Jul 1, 2009)

That's a good method. Especially so because you can easily restore the N249 if you don't like the change.


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## BMAN (Jun 9, 1999)

So both methods will work fine?


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## Twopnt016v (Jul 5, 2009)

BMAN said:


> So both methods will work fine?


 Yes... 
If you do the entire mod you can remove the vac reservoir from the valve cover and make the bay cleaner..... 
There would be no reason why you would ever want to go back from this mod... 
Here is a good DIY... 

http://uk-mkivs.net/forums/p/265883/1744207.aspx#1744207


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## 00B5A4 (Oct 28, 2011)

Twopnt016v said:


> Yes...
> If you do the entire mod you can remove the vac reservoir from the valve cover and make the bay cleaner.....
> There would be no reason why you would ever want to go back from this mod...
> Here is a good DIY...
> ...


 :thumbup:


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## 00B5A4 (Oct 28, 2011)

BMAN said:


> So both methods will work fine?


 yes but this way is easiest if you just want to try it out. 

this is what it looks like on an b5 a4 1.8 
 

hope this helps


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## BMAN (Jun 9, 1999)

00B5A4 said:


> yes but this way is easiest if you just want to try it out.
> 
> this is what it looks like on an b5 a4 1.8
> 
> ...


 Thanks so you think that would be the same on my 03 GTI? If so just plug the two hoses I pull off?


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## rodgertherabit (Apr 16, 2009)

IT should be. I just did this to my 20th after my headswap. 

Honestly, its been GREAT! Drivability hasnt changed really at all and on top of it my Forge007 is much quieter. Seems like running it off the manifold directly a lows a more deliberate reaction from the valve:thumbup:


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## BMAN (Jun 9, 1999)

Cool, I also have a 20th. Where did you tap into the manifold at? I'm getting a P1200 code so I hope this will take care of it. Thanks


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## rodgertherabit (Apr 16, 2009)

I just ran the DV to the small nipple adjacent to the FPR nipple.


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## BMAN (Jun 9, 1999)

Ok thanks I took a quick look at it tonight and my boost gauge is hooked to my FPR, did see the larger hose coming off the manifold just need to figure out how to tap into it.


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## MrAkalin (Jan 4, 2011)

Can't wait to do this to my car when I get it back. I'm just going to bypass the valve until I have time to get all the emissions deleted.


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## BMAN (Jun 9, 1999)

Thanks for all the help guys. I ended up bypassing the valve. It feels like I'm driving a new car. I now know way I was getting the P1200 code, the hose going to the N249 valve had a hole in it.

Before the bypass










And after


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## Twopnt016v (Jul 5, 2009)

:thumbup::thumbup::thumbup::thumbup::thumbup:
Everyone is always pleased with the after effects of bypassing!:beer::beer:


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## 00B5A4 (Oct 28, 2011)

:thumbup::thumbup::thumbup::thumbup::thumbup: looks good!


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## AmIdYfReAk (Nov 8, 2006)

LEBGTIMK4 said:


> remove the N249 valve and insert the connector with a 10w 330 Ohms resistor so you don't get any CEL, or a 10w 470 Ohms resistor will also work fine. I did to my car that ain't mapped yet and i felt the difference on the boost gauge!!


What's with 10watt? That is 40 times what's required, or 10 times for those paranoid users.


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## eljw24 (Jan 6, 2009)

Thought I'd add my experience to this thread.
My problem was where to tap for the DV. You see that I used the white OEM tee which would've gone to the N249.
My picture shows the hose marked in green is OEM for the N112 (untouched). The red hose is the bypass part.









I've been running like this for weeks now. It is slightly more responsive & a bit louder but no problems, codes or drawbacks experienced.

Hope this helps someone.


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## Typical_normie (Mar 16, 2021)

Twopnt016v said:


> It makes the diverter valve more responsive and will make the mid range smoother. Any surging issue will typically go away after bypassing the n249. The n249 controls the diverter valve so it will bleed boost off at times that you don't want to bleed off and that is how surging comes into play. Once you bypass the n249 and run your diverter valve vacuum hose off of the intake manifold the dv will work much better. and won't bleed off boost unnecessarily. I have this done to my car:thumbup:


Can this mod work in conjunction with the boost gauge using the same location for vacuum or is it better to look for a different vacuum location. TIA


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## Vegeta Gti (Feb 13, 2003)

Typical_normie said:


> Can this mod work in conjunction with the boost gauge using the same location for vacuum or is it better to look for a different vacuum location. TIA


Read the faq

Sent from my SM-N975U using Tapatalk


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## Twopnt016v (Jul 5, 2009)

Typical_normie said:


> Can this mod work in conjunction with the boost gauge using the same location for vacuum or is it better to look for a different vacuum location. TIA


 Yes it can. Many people run it that way. I haven't run a stock manifold in a long time but i'm pretty sure there are 2 vac fittings on the manifold. I would run the diverter valve vac line directly to 1 of those and run other items off the other fitting using Ts.


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