# Why bypass the N249?



## mk2michal (Sep 26, 2009)

I heard people bypass the n249 but I dont understand why. Could you guys please give me a little briefing and also is it recommended if you want to chip your car with unitronic (or any other company)


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## alextjoe (Aug 7, 2008)

most people do this to clean up the engine bay and mostly the top of the engine...i removes most of the vacuum line clutter and the big vacuum reservoir on the of the valve cover..

people also say that the DV response is much quicker and stronger as after removing all this junk it is hooked up to a direct vacuum source...

i wouldnt know if there was a difference i removed the n246/SAI/Combi valve/All the EVAP lines and the vacuum hard lines before putting the motor in my mk2..

but its is much cleaner looking!


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## dubinsincuwereindiapers (Jan 16, 2008)

DO IT.. no negative effects to be had.. From experience, im positive that mine reacts faster..


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## weenerdog3443 (Jul 5, 2007)

dubinsincuwereindiapers said:


> DO IT.. no negative effects to be had.. From experience, im positive that mine reacts faster..


sooo happy i did mine... it also makes it a ton easier trying to find boost leaks when you just have a couple hoses compared to 30 billion that come stock


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## Big_Tom (Aug 19, 2007)

i took all that ish out my engine bay and its so much easier to work on and you can see whats really going on under the hood without all the extra clutter


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## mk2michal (Sep 26, 2009)

you guys have a good like with picture how to bypass the n249?


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## alextjoe (Aug 7, 2008)

i dont have pics of how to bypass it....im really not sure what you mean by bypass it..do you mean just unplug and route a direct vacuum line from intake manifold to to DV or do you want to physically remove the entire n249 system???

anyways here is the link to do all of this

http://forums.vwvortex.com/zerothread?id=3111538


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## Cryser (Sep 9, 2009)

The N249 is used by the ECU to dump boost through your DV when it senses an overboost situation coming or is in effect.

The main reason in bypassing the N249 is to prevent this from happening, Since most the people in this forum are running elevated boost levels and want more boost/power taking this control away from the computer is a good thing.

In order to accomplish this task your DV is hooked up to a vacuum reservoir along with the N249(this is because you need vacuum to open a DV and if your engine is in boost your obviously not producing vacuum) This reservoir is just another space that has to fill up before the vacuum source actually gets to your DV to open under normal conditions.

So a secondary benefit to bypassing the N249 and this reservoir is a quicker response time(were talking milliseconds here) in the valve opening. not only that but since there is a direct line of boost going to the top without the reservoir the valve is also shut faster when you get back on the throttle between shifts. It gives a more direct feel to the car between shifts and when you get on it from a constant roll(I.E passing someone on the freeway)


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## sounrealx (Apr 4, 2007)

it's basically a solenoid that the ecu uses to decided whether or not the dv has vac pressure, and therefore can hold boost. If you take it out, the dv will function off of true vacuum pressure in the manifold. The n249 bracket also holds the n112, which controls the SAI pump. If you don't plan on removing the SAI, you should leave the n112 in there. 

http://uk-mkivs.net/forums/t/265883.aspx


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## WOB.018t (May 29, 2007)

Big_Tom said:


> i took all that ish out my engine bay and its so much easier to work on and you can see whats really going on under the hood without all the extra clutter


the ultimate VTA set-up


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## weenerdog3443 (Jul 5, 2007)

WOB.018t said:


> the ultimate VTA set-up


how mines runnin too


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## Big_Tom (Aug 19, 2007)

LOL VTA? vent to atmosphere im guessing?


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## WOB.018t (May 29, 2007)

Big_Tom said:


> LOL VTA? vent to atmosphere im guessing?


thats exactly right.

what do you have on the breather port on top of the filter housing?


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## bootymac (Apr 19, 2005)

sounrealx said:


> it's basically a solenoid that the ecu uses to decided whether or not the dv has vac pressure, and therefore can hold boost. If you take it out, the dv will function off of true vacuum pressure in the manifold. The n249 bracket also holds the n112, which controls the SAI pump. If you don't plan on removing the SAI, you should leave the n112 in there.
> 
> http://uk-mkivs.net/forums/t/265883.aspx


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## Big_Tom (Aug 19, 2007)

^^^ just tee off one of the other 2 or three lines coming off the manifold. my car didnt like sharing a boost gauge, dv, and the fpr on one line. now my dv has its own line str8 off the intake manifold



WOB.018t said:


> thats exactly right.
> 
> what do you have on the breather port on top of the filter housing?


i just have a 90 degree bend down and a hose that runs str8 down to the ground. looks much cleaner


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## bootymac (Apr 19, 2005)

What a clusterf*ck of vacuum lines. I bypassed the N249 and kept the N112 for the SAI. Managed to ditch all the hardlines as well by running the DV off the intake manifold and combi-valve directly to the N112.


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## mk2michal (Sep 26, 2009)

bootymac said:


> What a clusterf*ck of vacuum lines. I bypassed the N249 and kept the N112 for the SAI. Managed to ditch all the hardlines as well by running the DV off the intake manifold and combi-valve directly to the N112.


That all you got rid off when you took off the n249?


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## weenerdog3443 (Jul 5, 2007)

mk2michal said:


> That all you got rid off when you took off the n249?


you should see what he took out when he removed the motor:laugh::laugh::laugh:

When i did my turbo install and removed all the crap under there I ended up with bout 6 plastic bags of crap that i took out


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## Big_Tom (Aug 19, 2007)

i had 2 walmart bags full of stuff!


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## bootymac (Apr 19, 2005)

mk2michal said:


> That all you got rid off when you took off the n249?


Yup, most of them were vacuum lines going to the N249 valve. The hardlines were removed because I ran new vacuum lines for the DV and combi-valve. It's much cleaner and much more simpler now :thumbup:


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## sounrealx (Apr 4, 2007)

bootymac said:


> Thanks for sharing this link! I've been meaning to delete some vacuum accessories but I wanted to retain the SAI to prevent any fault codes.
> 
> Is there a better location to tap into for the DV's vacuum line? I already tapped into the FPR's vacuum line for my boost gauge and thought it would be ideal to use another source for the DV.


I had mine t'd off the fpr for a while and it messed up my fuel trims, so i bought a vacuum manifold which worked fine. i Then deleted the rest of the stuff under there so i got a free port on the intake manifold. If you want to go the vacuum manifold route, I can sell you mine.


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## Marcio (Sep 4, 2009)

what if i just put a T line on a vacuum line, maybe the FPR direct to the DV, and than close somehow the original hose that goes do the DV?
isnt it going to be bypassing the n249 same way?
thanks.


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## steve05ram360 (Aug 14, 2006)

Yes, plug the disconnected hose. This is what I did and it works great


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## ornithology (May 6, 2009)

bootymac said:


> what a clusterf*ck of vacuum lines. I bypassed the n249 and kept the n112 for the sai. Managed to ditch all the hardlines as well by running the dv off the intake manifold and combi-valve directly to the n112.


yo! Diy plz bootay


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## blownB6 (Nov 15, 2011)

nvm


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## Slimjimmn (Apr 8, 2006)

there is a reason vw went to electrical diverter valve...:laugh:


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## rains (May 30, 2008)

My car is quite a bit happier sans N249. My diverter valve is quite a bit more responsive, holds boost properly (as opposed to when-it-felt-like before), and it makes a 'better' noise now.

Now, mind you, half the hoses to my N249 were cracked, so it's not like it was 100% when I pulled it out.

Here's all I pulled out (not just the N249, the SAI, and emissions too)


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