Volkswagen Mark IV Forum banner
21 - 40 of 84 Posts

·
Registered
Joined
·
6 Posts
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 :)
 

·
Registered
Joined
·
301 Posts
Discussion Starter · #25 ·
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
 

·
Registered
Joined
·
301 Posts
Discussion Starter · #26 ·
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.
 

·
Registered
Joined
·
764 Posts
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.<o:p></o:p>

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

·
Registered
Joined
·
764 Posts
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.
 

·
Registered
Joined
·
81 Posts
Great guide mate.

Used this to do my bypass the weekend, only change i made was to tee into the pipe you show in this pic from the one way valve to inlet manifold

Posted Image


Only reason is i was always told by tuners to leave the FPR on its own dedicated vacuum line.

Also from the tee i used a small piece of 4mm vacuum line and still used one of the metal pipes to the DV to keep it looking as factory as possible.
 

·
Registered
Joined
·
547 Posts
Great guide mate.

Used this to do my bypass the weekend, only change i made was to tee into the pipe you show in this pic from the one way valve to inlet manifold



Only reason is i was always told by tuners to leave the FPR on its own dedicated vacuum line.

Also from the tee i used a small piece of 4mm vacuum line and still used one of the metal pipes to the DV to keep it looking as factory as possible.
do you plug the N249 electrical wire again?

and why as long as it is bypassed. in the above pic it looked unplugged.

thx
 

·
Registered
Joined
·
81 Posts
Yes i plugged the N249 back in as i think it may show a fault code up if not plugged in.

Only way to totally remove the valve would be to put in a resistor IMO.

The above pic is just to show routing of the vacuum lines and the work was still in progress.

HTH
 

·
Registered
Joined
·
1 Posts
Rather than using a T piece on the FPR line, I changed the brake servo check valve to a Mk2/Mk3 Golf one.

It has two manifold pressure take offs, I used one for the dump valve and one for a boost guage

Posted Image
 

·
Registered
Joined
·
835 Posts
Cheers for the guide. I just did this on my AUM. I snapped the nipples on the N112 valve so I ended up by passing that as well lol.

Now I have one vacuum line to the FPR and one to the DV. I want to reinstall my boost gauge but ran out of time today because it got dark. Does anybody know if the PCV vacuum line is the same as these other two? If it is, Im going to run my boost gauge directly from there because I have installed a catch can so no longer using that nipple.
 

·
Registered
Joined
·
23 Posts
see if i want to totally remove the 249 and 112 what happens with the vac pipe coming from the bottom of the plenum chamber? can i run this to the top of the dv and t piece it for a boost gauge? or is the boost gauge best routed from the fpr? i have alreay removed the sai and am having no issues with it as of yet
 

·
Registered
Joined
·
835 Posts
On your AUM you should have 4 nipples on the inlet manifold. One us on the side for the brake booster. The three on the bottom are first for the PCV system, second for the fpr and third for the n249, the n112 and eventually the dv. If you remove the pipe leading from the inlet to the n249/n112/dv system, you can run the dv from this nipple as i prefer to leave the fpr with its own vac supply (although i had my boost gauge teed into the fpr line for 6 months with no issues). Then if you have do the pcv simpliication you should have a spare nipple from that which you can run your boost gauge off of. If not you can tee into the dv line. I have done the pcv simplification but i didnt have enough hose to reach it all the way to the pcv nipple so had to block that with a bolt and tee into the dv lol.

Hope this all makes sense!!
 

·
Registered
Joined
·
23 Posts
ok cheers,what size is the nipple under the inlet that i would be using for the dv after binning the 249/112 stuff? do i need to put resistors in the 2 connectors that are on the metal plate with all the 249/112 stuff?
 
21 - 40 of 84 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top