[Mk4 Golf] My Guide To Removing The N249 Valve, With Pictures - D.I.Y Guides and How to Instructions - uk-mkivs

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My Guide To Removing The N249 Valve, With Pictures



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#1 BaV

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Posted 17 April 2009 - 09:30 AM

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.
1-4.jpg

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.
2-3.jpg
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.
4-2.jpg

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.
10-1.jpg
11-1.jpg
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.
3-2.jpg

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)
5-1.jpg

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.
6-1.jpg

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.
7-1.jpg
8-1.jpg

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!
9-1.jpg

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 as well.
12.jpg

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


Edited by old_n07, 01 March 2014 - 08:20 PM.
Pictures updated post forum move

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#2 Pat

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Posted 18 April 2009 - 06:42 AM

Richard that is a fantastic writeup - I'm sure lots of people will be using this guide in the future [y] Nice one!

#3 chromepete

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Posted 18 April 2009 - 07:00 AM

 Really clear guide, nice pics!


Why is the valve bad?



#4 AzRiz

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Posted 18 April 2009 - 09:25 AM

Awesome guide Bav, thanks for doing it, will be using it after uni exams to re-do the PCV system and add a catch can.


Az



#5 BaV

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Posted 18 April 2009 - 09:32 AM

Cheers guys glad to help.


The valve can be bad because it doesnt always operate the DV as you would want it to operate. Sometimes it opens it when it should be shut, resulting in jerky power delivery.


Next weekend i will hopefully trying to make a catch tank on a low budget so if i manage to get all the bits i need i will make a guide for that aswel.


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#6 AnniGTI

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Posted 18 April 2009 - 10:08 AM

Nice write up can I ask, when does this valve cause problems? Also I have a catch can for sale in the classifieds. I must admit that I have had the car hesitate on the acceleration. I'll keep this one to do another day.



#7 BaV

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Posted 18 April 2009 - 12:23 PM

There isnt really a set time when it causes problems it just can cause them when you come on and off the power.  If you have hesitation when coming on the power then i would say that its worth a go.


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#8 chromepete

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Posted 19 April 2009 - 07:34 AM

saw a nice DIY catchtank here: http://www.autospeed...26/article.html


Was thinking maybe an old charcoal filter might do the same job??



#9 skrewface

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Posted 07 May 2009 - 10:59 AM

Great write up BaV


Am i right in saying this works on all 1.8 Turbo's including the Audi A3


Is this an advisable mod for people with standard or tuned cars?


Marv



#10 ianmorgan50

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Posted 08 June 2009 - 12:55 PM

 i think im gunna have to give this a go



#11 ca-18

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Posted 08 June 2009 - 02:46 PM

 why would u do this? me no understand!



#12 BaV

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Posted 11 June 2009 - 12:06 PM

You only really need to do it if you think your car is throwing away boost when accelerating.


It seems to have made my power feel alot stronger.


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#13 ca-18

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Posted 11 June 2009 - 03:33 PM

 is there no downside to this?  i mentioned this to an engineer in my work and he said something about it over pressurisng something.... would this be right???



#14 BaV

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Posted 11 June 2009 - 04:46 PM

 is there no downside to this?  i mentioned this to an engineer in my work and he said something about it over pressurisng something.... would this be right???

No, the only downside would be that the ECU no longer has the ability to open the DV. Therefor the ECU cannot protect for standard overboosting.


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#15 brandon888

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Posted 29 July 2009 - 07:20 PM

 i already use one  t piece for my boost gauge so how can i overcome this ....



#16 BaV

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Posted 30 July 2009 - 03:05 PM

you dont need to overcome that?


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#17 albad

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Posted 27 October 2009 - 05:56 PM

Hi Bav,


Thanks for the write up.


What are the advantages of bypassing the valve totally as you have done, as opposed to just connecting the top of the DV to the FPR and intake manifold (and capping off the relevant bits)?


Alex



#18 Simon_1.8T

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Posted 27 October 2009 - 06:27 PM

 Great write up mate, looking into doing this on mine as at times jerky power delivery on boost.


Si



#19 Golfin

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Posted 27 October 2009 - 06:57 PM

Snap as above although this looks alot more complicated than another version i saw where one of the pipes was capped and another fed from somehwere else.. Although very nice write up mate! Wanna do mine? Loads of beer tea and biscuits!!? haha



#20 BaV

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Posted 28 October 2009 - 05:00 PM

Lol its easy enough to do yourself mate!



The reason i have done it this way and not just changed the DV hose is because i want to try and keep things as simple as possible on the engine and also this way i know where all the little pipes are going to ect.. so if ever i get a boost leak ect i will know where to look


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#21 albad

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Posted 28 October 2009 - 06:11 PM

ok, good point. thanks again!



#22 vee_dub_modder

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Posted 30 October 2009 - 04:12 PM

why not just blank the metal pipe to the old vac resivior and metal pipe to the dv then T off the FPR vac pipe??? much quicker?  or failing that rip out the N249 & N112 all together and replace them with resistors. can also rip the SAI pump and combi valve too :)


just need to make a small blanking plate for the SAI/combi valve and a couple of 330 ohm 10W resistors :D


Good thread though :)



#23 brandon888

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Posted 31 October 2009 - 06:36 AM

U can get the blank plate for sai from forge ....

#24 albad

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Posted 04 November 2009 - 03:17 PM

Hi Bav, I've posted here about a possible problem with tee'ing into the FPR line:


https://uk-mkivs.net/...05.aspx#2058693


Would appreciate your input on it!



#25 BaV

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Posted 04 November 2009 - 04:46 PM

Basically mate, if the FPR line say starts to leak weather its the
standard line or a new one with a T piece in the fuel will start to
lean off, this can be drastically or not.  Either way is not good.


The only reason it is worse with a T in place is because that T now
has 3 joins on it rather than none.  So therfore more chance of a
Vacuum leak.


As long as you make good connections around the T and all new hoses and also check them regularly you should be fine


Hope thats clear


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#26 BaV

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Posted 04 November 2009 - 04:50 PM

why not just blank the metal pipe to the old vac resivior and metal pipe to the dv then T off the FPR vac pipe??? much quicker?  or failing that rip out the N249 & N112 all together and replace them with resistors. can also rip the SAI pump and combi valve too :)

just need to make a small blanking plate for the SAI/combi valve and a couple of 330 ohm 10W resistors :D

Good thread though :)

 

Well i did write an entire guide like this one for removing the SAI and combi valve ect. But after doing it to my car and driving it for a week i stuck it all back on and never looked back!

The car ran like a bag of poo, hesitating all the time on launching.  And also failed an MOT that week on emmisions by a long shot.

The myth that the SAI does nothing once the car is warm is a load of rubbish!

Im sure if you removed it all and then got a custom remap they could smooth out most of the problems but obviously this isnt going to be ideal for many people.


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#27 albad

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Posted 05 November 2009 - 05:35 AM

 Thanks Bav, that makes a good deal of sense. Much appreciated!



#28 NormanHomes

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Posted 09 November 2009 - 11:03 AM

 good write up that well done


 


would it make any difference if you put the T peice after the one way valve and run that to the DV?



#29 AndiGTTDI

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Posted 05 December 2009 - 07:17 AM


 This is an excellent write up, I just carried it out on my 25th Anni and its done wonders for it. Before it used to surge like hell when coming of throttle and the boost was a little spiky.



Runs like a dream now. So hats of to BaV, and have a beer on me.



 




#30 AndiGTTDI

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Posted 05 December 2009 - 07:20 AM

 good write up that well done

 

would it make any difference if you put the T peice after the one way valve and run that to the DV?

I just ran my boost gauge from after the one way valve to the vacume on the manifold. Works fine.

And then the other vacume to the FPR and Dumpvalve.







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