Author Topic: Guide to removing / bypassing the N249 valve.  (Read 28253 times)

Offline BaV

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Guide to removing / bypassing the N249 valve.
« on: 17 April 2009, 15:33 »
This is my guide to Removing the N249 Valve that operates the Vacuum pipe going to the DV.

There are many ways of doing this but i think this way is nice, simple and straight forward!

I take no responsibility if you copy this guide and something goes wrong!

Things you need:

     Matterials:

     3mm Vacuum pipe, i bought a 3m pack and still have probably 1m left over
     One T piece for 3mm Vacuum pipe
     Some small cable ties

     Tools:

     Flat head screwdriver
     Side cutters
     pliers
     5mm Allen Key
     10mm socket & Ratchet

The first thing to do is to remove both engine covers.  By both i mean the main engine cover and the small one that going around the dip stick.

Then start off by removing the standard vacuum pipe that goes to the top of your DV, if you trace this back a short way it goes to a small metal pipe.  You need to completely remove the vacuum tube from the metal pipe.  Mine was impossible to get off so in the end i just cut it off with a stanley knife, but you could try tugging at it with pliers.

Once that tube is removed you can then remove the black reservoir that sits on top of coil No.4.  To remove this there is a 10mm nut holding the reservoir on to its mounting bracket, undo the nut then the reservoir comes away from the bracket.  Then you need to pull the small black tube that goes from the reservoir to another one of those small metal pipes. You need to again completely remove this tube and take the reservoir with it.  You can also remove the reservoir mounting bracket which is held on to the rocker head cover by three 5mm allen key bolts.

So at this point you should have nothing going to the top of your DV, no reservoir on the top of coil No.4 and also two small metal pipes with nothing connected to anymore.  The two metal pipes are shown in this picture below.



The next stage is to gain access to the plate at the front of the engine that has the N249 and N112 bolted to on the under side.  See picture below.



Firstly you will see a black plastic corrigated hose that is bolted to the front of this plate, it is held on by two 10mm nuts which you need to remove. Once those two nuts are removed you can completely get this pipe out of the way by uncliping it where it has a join and then swing it to the left hand side of the engine and hooking it round something to hold it.  The picture below shows where it has the join that can be unclipped.



Once that black pipe is out of the way you have to undo two 5mm allen key bolts that hold the plate onto the inlet manifold.  Now you will notice another black corrigated pipe that is fixed to the underside of the plate with another 10mm nut. Again, all you have to do is take that nut off and then that hose is not in the way. The plate is also clipped in to the dipstick guide so be carefull not to snap that.  Once all of this has been done the plate is now ready to be removed.

The next thing to do is to remove the two electrical connectors that join the valves on the underside of that plate.  This is a bit fiddly but is easily done with small hands!  You need to squeeze the metal bits on the plug to remove them.  I have shown the location of both of the plugs in the pictures below.





Now you will see on the right hand side of the plate three tubes going from the bottom to three small metal pipes.  They are shown in this picture below.



On my car the one on the left was a braided hose and the other two where rubber hoses, i would think this would be the same on all AUM's.  Now cut these three pipes with a pair of side cutters.

Once you have cut those three pipes you should be able to swing the left hand side of that plate over to the right so you can now see the bottom of the plate.  Shown in the picture below (ignore the corrigated pipe i didnt clip it up out the way at first)



Now you will also see in that picture that i have pointed out the only place where that plate is still connected to. That is the pipe that is giving those valves there vacuum feed. That pipe needs to be removed from the intake manifold, it should pull off prety easy.  Once that pipe is removed then the whole plate should be able to be removed from the engine bay.

Now you have to remove all of the standard pipework that is connected to both of the valves on that plate.  Make sure you take care in removing all of the standard pipework so you dont damage any of the ports on the two valves.

Now you need to copy what i have done in this picture below, using the original one way valve and leaving about 25cm or so of vacuum tube on the two pipes that go out of site.  you will also notice that i put a cable tie around all of the joints.



Now you need to take the tube that comes from the top of the one way valve and plug it in to the inlet manifold where the original valves vacuum feed was.  Shown in the pictures below.  Also try and get a cable tie round this joint.





Next you have to remove the rest of the three cut vacuum pipes that were joined to the valves on the underside of the plate.  These two rubber tubes originally joined the metal pipes and went to the other end where we removed the DV pipe and the reservoir on top of coil No.4.  Now because obviosuly we have removed the two tubes at the other end going to the DV and the Reservoir we no longer need anything joined to the metal pipes at the front end so just completely remove the rest of the rubber tubes you cut and leave the metal pipes with nothing on.

The other tube that you cut was the braided one.  This joins another small metal pipe and goes to the cars Secondary Air intake System.  I have left this on the car for the time being so we need to give this its vacuum feed from the N112 valve.  You now have to completely remove whats left of the braided tube from the metal pipe it connects to and then take your other new vacuum feed to that same metal pipe  (you use the vacuum pipe coming from the left hand side of the N112 shown in the picture below)  Hope that makes sense!



Once you have connected both of the tubes coming from that plate you can now swing the plate back over and bolt it back on the car in the same way that you removed it, including the two black plastic corrigated tubes that you had to move to get the plate off.  And also dont forget to reconnect both of the small electrical plugs to the valves otherwise the car will show an engine management fault.

Once all this has been done all you need to do is give the DV another Vacuum feed.  The easiest way to do this is to replace the braided line going from the bottom of the inlet manifold to the Fuel pressure regulator with a new tube that has a T piece in it.  And then from the T piece run a vacuum tube straight to the top of your DV.  You will see in my picture below that i have two T pieces in this Vacuum line. This is because i am running a boost gauge from here aswel.



Then put your engine covers back on and now your N249 bypass is complete!

It can take a couple of days worth of driving for the car to get used to the change so dont be annoyed if its a little jerky at first.

Hope this guide is clear enough and helps people! I will edit it if anyone has any sugestions on how to make it a bit simpler!

Cheers, Richard


The writer of this guide and GolfGTI.co.uk accept no responsibility of damage to your car when using this guide. Use at your own risk.
« Last Edit: 18 April 2009, 11:24 by BaV »

Offline barry-gti

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Re: Guide to removing / bypassing the N249 valve.
« Reply #1 on: 17 April 2009, 17:26 »
sounds good. ill give it a try when i get paid

cheers mate

Offline jonnyturbo

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Re: Guide to removing / bypassing the N249 valve.
« Reply #2 on: 18 April 2009, 09:14 »
good guide mate  :cool:
Gone but still keeping a close eye on it...

Mk4 golf 1.8t AUM Hybrid K03s. Custom Mapped by R-tech to 260bhp. CR hybrid turbo Audi TT injectors / fuel pump, Forge tip,THS FMIC,Carbonio CAI, Full milltek turbo back, N249 bypass, Fully poly bushed, Weitec coils. Genuine R32 front bumper and Genuine R-line rear, Genuine Porsche twists, Anniversary black interior.

Offline BaV

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Re: Guide to removing / bypassing the N249 valve.
« Reply #3 on: 18 April 2009, 11:25 »
cheers hope i didnt waffle too much lol, and at first all the spacing went wrong on the text because i wrote it in notepad but i have sorted that now so its easier to read lol

Offline Car nut

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Re: Guide to removing / bypassing the N249 valve.
« Reply #4 on: 08 May 2009, 11:47 »
Bav, you should get some blue piping on your engine  :grin: :grin:

Nice guide  :wink:
Daily Hack - '53 - AUM - GTI T  "The Black Beaver" :wink:
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Offline Gozza

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Re: Guide to removing / bypassing the N249 valve.
« Reply #5 on: 13 May 2009, 17:04 »
What benefit does this give ?

Sorry if its been mentioned but I cant see it.

Thanks

Offline barry-gti

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Re: Guide to removing / bypassing the N249 valve.
« Reply #6 on: 13 May 2009, 20:18 »
i think it makes it more responsive because your not relying on the ECU to tell the N249 when to open and close the DV.

Offline GregUK

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Re: Guide to removing / bypassing the N249 valve.
« Reply #7 on: 18 May 2009, 13:36 »
I did this mod yesterday and am surprised by the difference it has made. Why VW introduce this heap of !"£$%^&*, I don't know!

I highly recommend this to anyone considering it.

Excellent guide, thanks BaV! :grin:

Offline jtomlin

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Re: Guide to removing / bypassing the N249 valve.
« Reply #8 on: 21 May 2009, 23:44 »
so it just makes the throttle a bit more responsive? and risk of anything exploding..?

Offline barry-gti

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Re: Guide to removing / bypassing the N249 valve.
« Reply #9 on: 22 May 2009, 08:26 »
no. it does the same job but without the N249