Bypassing the N249 - An Easier Approach

[dbrowne1]

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.

[dbrowne1]

All you need to do this is:

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

[Seanathan]

very nice man. for now I was just going to cap of the line from the dv valve, and run a new one.

[nrml]

always good to see useful info on this forum

[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.

[turbovw18]

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

[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.

[jamesb]

heh, why use a T when you can use a 90 degree and be done with it. tahts all I did.

[[TSR] 33seven]

Alrirght, right now, i'm going to switch DVs from Hyperboost into 710N dv, i'll let everyone know...

I'm running UPsolute, AEm cai, ecs race H valve, overboost solution kit

[Italian GTI 1.8T]

done! awesom mod and onlytook $8 and 15 mins.

[[TSR] 33seven]

damn it!! i'm missing a cap, oh well, i'll do it tomorrow...but i just put back my 710N dv, and it's butterly smooth boosting at 19-20psi, i set my overboost solution kit to 1 1/2 thread...so far no limp!

[DJKeebler]

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.

[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

[dbrowne1]

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.

[polskaGKB]

Whats the ponit of bypassing the N249?

[BigWoo]

from what ive gathered, so the computer doesnt control the DV, only the boost/vacuumm from the intake.

[JettaRed]

Is the sole purpose to eliminate surging or fluttering at high boost levels (>15 psi)?

[dbrowne1]

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.

[JettaRed]

It amazes me how every car is soooo different.

[hugemikeyd]

that is a great way to do it, keeps it looking stock since you are changing an area normally hidden by engine covers...

[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.

[hugemikeyd]

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.

[coolvdub]

Okay, thanks for the advice. I will do exactly that.

[turbotazzy]

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

[SB_Beetle]

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.

Get rid of any braided lines you have and replace them with true vacuume lines. The braided lines are prone to rot and give you all kinds of seemingly invisible issues.

[hootyburra]

great thread, will be trying this soon.

[J-tec]

I did this about 6-7 months ago now, and could never figure out why i couldn't pass inspection.

I kept getting the P0411-35-00 - Secondary air pump incorrect flow detected and couldn't figure out why until tonight

I replaced the combi valve, n112, etc. thinking it could be something bad within those routes, lastly thinking about changing the actual pump.

After banging my head against a wall a few dozen times, i got a vacuum pressure tester and tested the vac lines between the combi valve and the n112 while the pump was on. I had no vac at all! I checked the expansion tank, no vac pressure there either!

I then check under the manifold to realize that a line i capped for the n249 block was actually blocking off all the vac pressure to the n249,n112, and expansion tank. The section i capped was the T section of the T valve in the vacuum line running to the n249. The port on the intake manifold where that n249 hose used to plug into was now the vac line for the DV. So i unplugged that, put the DV vac hose back to the position where it was stock on the hardline by the TIP and put the N249 valve hose back to the port on the intake mani.

Fired the car up, logged group 077, got the SAI to turn on and yes! i have around 0-4.0 g/s flowing through the system! i had -100 g/s when there was no vaccum, just incase some of you might be seeing that.

I just wanted to let everyone know because this was one of the most frustrating things to figure out. I was told over and over that blocking the n249 will not affect passing emissions, but IT WILL!

[goualon69]

some picture of what you are talking? because i plan to do it, i have to try everything to solve my problem! thanks

[bump909]

awesome, thanks for the write up dbrowne. my part throttle is horrible.. hopefully this will improve it.

[guywhoisjustin]

Would this mod be any good with stock engine?

[dbrowne1]

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.

[QT_GTI]

pics to show?

[4ceFed4]

Of what, the two 10mm nuts I removed? Can someone who has already done this mod please answer the question I asked in my previous post.

[outlaw]

[4ceFed4]

I finished this mod and the results are noticable but not as dramatic as I was hoping for. On my car the correct hose ended up being the left hose in the picture on this post. The easiest way to determine which line to T into the FPR line is to disconnect one of them, and blow air into the hose that connects to the top of the DV, much simpler than trying to trace the line with your eyes or finger.