I have been having low boost problems and have checked the install of the B.C. and all the main vaccum lines as well.
when I was at my local 7 meet, we are pretty sure that it is a line under the intake manifold.
I also plan on removing the air pump and acv. while I am at it.


Well to get straight to the ?'s.
1. Is there a diagram to the vaccum line connections under the manifold?

2. Can I take off just the air pump and take the acv off later?

This is my first time taking off the manifold. Does anyone have any advice or things to look out for while doing this. I have a 89T2


Thanks,
Josh

 

1. Here is the TRUE diagram. The one in the FSM is wrong.


2. Yes, just cover the hole it leaves with something.


Remember there are 5 bolts on the pass side of the UIM, 4 around the sides, and 1 in the middle. Then there is the one on the TB that is a bitch to get off. Leave it off if you do get it, you won't need to put it back on. There are 4 nipples on the back of the TB, mark the hoses and nipples with something.

 

1. Go to www.fc3s.org and go under manuals and you'll see an S5 FSM and it'll have the diagrams you need.

2. Yes, you can take the air pump off now and just leave the ACV on. Make sure that when you take the air pump off that you dont have any stock cats on or they will get clogged up. I think that the precats can be on with no air pump, but i wouldnt try it. And with out the cats you may get boost creep, so just be careful.

As for removing the intake, make sure you have gasket material or new gaskets incase the ones that are on there break when you take them off. Go ahead and buy some 1/8" ID tubing incase you break a vac line or find one that is broken (i just get mine from "Home Depot" or "Lowes") That should be about it, and keep up with your bolts and where they go and things, but thats a given. Its all pretty easy man, good luck!

Edit: I wasnt aware that the diagram in the FSM is incorrect as i dont ever use it. Sorry for the mistake.

 

as far as ? 2 goes I have the dual alternator pulley so I am going to get 2 new belts for that. I dont have a cat so that wont be a problem.

Also where can I get the gasket? I have a pretty fresh engine that only has 7k on it.

Are all the lines under the manifold 1/8"? Because one is cracked or dissconnected. Or at least it better be because I cant find my boost prob!!! This is my last resort!!

 

AS for the gasket, its not probable that you will break them, but if they do better safe than sorry. Just go to the auto parts store and get a roll of the grey gasket material. It'll be like a few bucks and just cut your own gasket out of it with a razor.

 

What kind of boost problems are you having?

 

Also thanks AreExSeven for the diagram

 

I hit 5 psi in 1st, 8psi in 2nd and 11 psi in 3rd 4th and 5th. I have a garret to4b compressor with a hitachi ht-18 ported wastegate. Also I have RB 3" downpipe with a custom 3" midpipe and Greddy dual power extreme. I have the old apexi avcr

 

um... Maybe your wastegate is sticking? hell if i know

 

Exactly what I was gonna suggest.


Have you checked it?

 

Or maybe you ported it too much?

 

well i have my duty on the avcr set to .70
I dont know who ported it because it was that way before I bought it.
The turbo itself is damn near brand new. Only like 3k on it.

 

And how long has it been causing you problems?

 

set the duty on 1.0!

 

Theres no reason that would cause the lowered boost. You cant restrict boost with a boost controller, so thats not the problem.

 

well when I bought it there was a highflow cat in it. since it was from cali. But now I got it back to michigan where they dont test for anything I got that out, and now it is just a straight 3" pipe.
When I bought it he told me that when I took out the cat I would run high boost. But.......it hasnt been the case. The normal duty setting which was waaayyy lower caused me to have even lower boost. And since I turned that up it has gotten better but I dont know how much higher I want to have it.

 

I am on the way to go do that right now!!

 

well if it set lower it opens sooner so therefore less boost.

 

Well if it never boosted good since you bought it, I would start my search with the wastegate (after you do the things that don't require tearing the car apart first). If its not that, then we can check other things. But I'm betting with the port job came too much open space for air to flow out.

 

about that! if your wastegate is ported too much and you have a factory exhaust wheel and a t04 compressor wheel you will have boost creep in a different fasion your boost creep will be at low rpm's and will surge at high rpm's so if your wastegate isn't ported enough i can see why you would be having these problems! but if it is not you would have to look more indepth!

 

So you are saying that it isnt ported enough? I didnt do any of this work so I truley have no idea. I have only had the car like 2 months and it is a huge learning process.

Thanks to everyone for posting please keep the posts coming!
I feel like a sponge soaking up tons of new info

 

Im not sure i understand how an underly ported wastegate would cause low boost..... that just doesnt seem to make sense to me. Overly ported, yes, it may be leting too much exhaust gas out and not spinning the turbine enough. I would check it out and find out though. Jreynish, care to go more indebth as to why an underly ported wastegate would cause a boost leak? Thanks

 

yes! either it isn't ported enough or not at all from the symptoms that you have given me with the new compressor wheel it would give you the effects that i had written above! this is what you need to do is simply check the turbo! it is REALLY EASY TO REMOVE! and check the shaft play and the port on the wastegate this can be done in two hours taken off +inspected + reinstalled

 

So you dont see this being a vaccum line prob. That is what a guy who runs a local rotary shop figured it would be. He said that it is prob in the rat nest under the intake manifold.

 

Roy James:
the underported wastegate with the t04 compressor wheel makes everything different it would not make for a boost leak but it would account for ALL of the symptoms that he had descibed above!
See the factory exhaust wheel would not spin as fast a a t04 exhaust wheel so the "hybrid" turbo is spinning almost like two speeds (exhaust / Compressor ) right so you would get funky boost spike surge and lag all in the same time IF the wastegate is not ported to match... can anybody else back me up on my theory or am I out to lunch! I am pretty sure that it makes sense! I may not be explaining it properly!