Just remove the ac&cv (blockoff plate) remove the rats nest, get some fuel line and run it directly to the fuel rails for the feed/return lines... After that you just cap all the vacuum lines except the one that goes from the LIM to the dynamic chamber (the one for the injectors at idle), connect the FPR directly to one on the dynamic chamber, and you leave the boost sensor connected to the UIM on the stock nipple... everything else, capped.

could we have more detail? like, maybe a vacuum routing diagram? excuse my slowness, but I'm sure someone else will eventually have these same questions



ac&cv?

what exactly is the rats nest? how do we know how to remove it if we don't know [specifically] what it is?

maybe before and after pics?



just trying to clarify

The rats nest is the metal rack that holds most turbo related solinoids and metal vacum routes.

thank you for that descriptive (no, I'm not being sarcastic)



what about for n/a?

i'll take pics of it later, the thing is, if you have a shop manual or have downloaded a vacuum diagram for your car, it's straightforward. You're removing the rats nest because you've eliminated the emissions junk, which renders the rats nest pretty pointless (theres so much vacuum line it makes sense to have it all in steel tubes routed nicely so you can figure out whats going on when you connect the emissions junk). So when you remove it, you just take it out, cut off the brackets (you still need the integral brackets which support the intake) and throw it away.



Now you look at what you have left, likely fuel pressure regulator, boost sensor, and thats probably it unless you have a turboii, which I have not done so I'm not sure what else is on that car through the rats nest, probably a bit.



You cap everything but the **** you have kept, use the vacuum diagram to find out where those things got their vacuum source before, and just run a vacuum line directly to that source. On NA there is a line going from the LIM between the primary injectors, up to the dynamic chamber, you keep this as it is supposed to improve fuel atomization at low rpms. You run your FPR straight to the back of the dynamic chamber, by the BACV and AWS solenoid theres a nipple. Then you take the boost sensor and run it directly to the UIM, near the junction between the UIM and LIM... it's right in the center on the side facing the passenger side of the engine bay. Cap the rest. It's that simple.



Don't forget your two fuel lines, the feed and return, just get fuel injection hose from the store and run the lines directly to the fuel rails over the block.



Realise you are eliminating some things that are supposed to improve 'driveability', some of these things don't always see vacuum.. the solenoids are used to control that. Your mileage may vary, I'm happy with my removal so far though.



I'll try take some pics later.

what noticeable downsides are there?

and when you say mileage may vary, do you mean better or worse?

Pengaru, did you get some pics yet?I'm wondering what to do with the switching actuator and switching solenoid they refer to in the manual.IT ties in at the metal line under the UIM on the T2 engine.S4 to be exact.I want it as clean as I can get to my NA on the block.



Thanks

Luis

i am in the procces of doing this and i have a hayns or whatever manual, i have the intake off and plan to pollish the out side and paint it to match the accesories(ricer, i know)if you have pics or if you could take some of yours

and send it to me i have a 89 gtu it might be a GTUs?

sorry no pics yet i've been busy with reverse engineering the haltech, i'll try get some this upcoming weekend if it gets nice outside.

Damn.I'm 90% done and theres the vaccums for the UIM right next to the TB that go to the LIM.I wonder if I have to cap those too?

just wanted to comment on this.. I took out the rats nest per these instructions on an S4 NA, ended up with 3 vacuum lines, and the car runs great.

Glad to hear it, my car ran fine too for the couple days I had that setup in place.... now with the TWM everythings different.



The only room for error is placement for the remaining vacuum lines, if you don't put them back to the nipples they originally connected to (via the rats nest before) you might goof up and end up on a nipple that sources before the throttle body (no/little vacuum with throttle closed), which would be bad.



The other thing to be careful about is, if you replace the vacuum lines, there is an orifice in the boost sensor line, you want to keep the orifice. Some people have alot of problems without it present. Like I said before, your mileage may vary.

hmmm, I didn't notice an orifice in that original line and I did replace the 3 lines with silicone tubing... like I said it is running fine though.



What symptoms should I notice with the orifice gone (which it is)?

from what I remember it's often linked to hesitations.



the boost sensor is in a kindof bad place to get pressure, being right on one of the primary intake runner, pretty close to the engine port, it gets alot of pulsations. The orifice is there to restrict this so the signal can be a bit smoother for the ecu... you can think of it as a damper.



As far as I know the exact function of the boost sensor is not documented though there are some people trying to reverse engineer the stock ECU to better understand how it works, from what I've gathered it's main use is advancing the timing, so with the pulsations it the timing advance might be a bit wacky.



However, some people have left the orifice out and claim no problems *shrug* it seems pretty car specific, one thing I do know is mazda engineers probably put it there for a reason, and it isnt a significant weight penalty, doesnt make things significantly more complicated, nor does it clutter the engine bay or make the car more difficult to work on.... and as far as I can tell it does not hurt the performance.



So I don't see any reason to remove the orifice https://www.nopistons.com/forums/pub...IR#>/smile.png

Would this help on an n/a?

I took it all out on mine and it just cleans everything up, simplifies, and makes it easier to work on the engine... If you're saying help in terms of power increase.. probably not. Another good thing though is that I checked the wiring harness and wrapped it up good with electric tape which it needed, cleaned up all the grounds in there, and ran new fuel lines... these things are good for a car so old.

s4 n/a rats nest removed

https://www.nopistons.com/forums/upl...1054613177.jpg

new fuel lines ran, 5/16". Fuel feed come from fuel filter to primary rail, return line comes from the secondary rail

https://www.nopistons.com/forums/upl...1054613202.jpg

no more rats nest!

https://www.nopistons.com/forums/upl...1054613232.jpg

When caping off all the extra lines, do you cap all of those lines running around the TB

Yes, or you'll have a vac leak

when you remove the rats nest what do you do to support the TB since the rats nest holds it up in place? also the 3 vac lines in the front of the TB have to do with the oil system right, do those connect to the rats nest or can those just be left alone?

Did you use high pressure fuel hose? I couldn't find any at the local store, so I used standard fuel hose. Also, the injector aerator screen broke off of my UIM when I was taking it off. Do you think everything will work fine? I'm waiting for the gasket maker to seal under the block-off plates before I start it...



One more thing: I ran my FPR to one of the vacuum nipples on the LIM, right in front. Will this be OK, instead of the back of the dynamic chamber?

It never hurts to use HP hose but as long as the hose you did purchase was meant for use in the fuel system (gasoline can degrade standard rubber quite rapidly) than you are okay.



The aerator screens are good to have, and I'd try to allocate a new one but you'll be alright if you are missing them. Just make sure that the other injector from that set has its screen removed as well to maintain balance.



The FPR vacuum can come from any reliable vacuum source, you should be okay at that. Some have removed this solenoid completely, I chose to keep it for the sake of drivability, and minor space it consumes, I just relocated it. (FD3S)



~Kris

Mine's running alright now, just gotta ask everyone: what did you do with your extra wiring? cut the connectors and tape back the wires, or what?

I just left them hanging.