Boosting 12-13psi please help?
 

Ok so my boost gauge is reading 12-13psi, ive searched and couldnt find anything exact on this. I have already ported the wastegate for the boost creep problem and put a plate in between the downpipe and midpipe just for insurance. I have a non-seq setup and manual boost controller. I have the boost controller turned all the way down but it still goes right up to 12psi. Im not hitting the fuel cut or anything. Could having the boost controller on the wrong prong on the wastgate actuator cause this? Also the prong on the turbo that is right beside the prong hooked to the mbc, should i have that capped off?

You must open a MBC boost controller to lower boost. Closing it increases boost. If your wastegate line nipples have restrictors in them, a manual boost controller won't help unless you drill out the restrictors first.

Dont see any restrictors, never really heard of that. As for the boost controller it says right on the outside of it which direction turns up/down so im not that much of a retard. Anymore input on this would be greatly appreciated.

well it will simply not be able to raise boost at all if you have a direct open vaccum hose to the wastegate actuator from a boost pressure source...the more air to the wastegate = opens quicker = less boost.....make sure when ur boost controller is turned down thats its open completely and air flows through it as if its just a coupler in the line.....also if the line pops off or is wired wrong you will get insane spike

for non seq i would guess you are rid of your pre-control actuator

so you should have a line coming from the y pipe / turbo /source >> to the passenger side of the wastegate actuator and cap the other end of the actuator! and the open hole on the y pipe that would run to the pre control actuator

Getting boost is not my problem its bringing it down to 10psi on my non seq setup. Im going to try to explain how its setup but ill post pics later tonight to help. All of the nipples on my y-pipe are capped off except my blowoff valve. My MBC is hooked into the a nipple coming off of the top wastegate actuator and the other nipple on the actuator is capped off. The other vacuum line coming off my MBC is going to the front turbo. Now on the front intake(the shorter one) there are 2 vacuum lines coming out of it, the first one is capped off the second one has a vacuum line running out of it to somewhere i cant see. Now i just notice that that line was snapped off at the base. Could this be my problem or is my non-seq setup all screwed up. I bought the car with it setup this way. Ill post pic later and circle all of my vacuum lines.

bypass the MBC and see what happends.. sounds like you might have a restricter pill in the boost line for the waste gate.

If you bypass the MBC and get 8psi.. then try this. There are two pressure lines coming out of the turbo compressor. One for the wastegate, and for the prespool (stock setup). Get both outputs and T them together, then run that source to the mbc, then to the waste gate.

Some MBC have a air bleed to prevent lockup during shfits.. and if your turbo has the boost pill built into the out put line, this can some times cause the waste gate to not fully open till at a much higher boost level(the air is bleed at the boost controller instead of going to the waste gate)Having both pressure sourced T-ed together will provide more air volume that will have the boost controller function properly.

Hope that makes sense.

Ok so how would i bypass the MBC? and how can i tell if it has a pill in the out line? Also my MBC is a turboxs, i dont know if that makes a difference. I never had any problems with the setup until i got these new turbos a couple weeks ago. I didnt think i would have any problems since i just swapped all the lines over to those turbos.

Ok so i did a little research and im almost positive i dont have any pills unless there is one inside the actual niple coming off the turn. There is no pills in the vacuum lines though. Do i need to add pills? or remove them if there is one in the nipple coming off the turbo?

You have a MBC. It replaces the stock solenoid and pill, so it sounds like it's set up properly. It should be between the actuator and compressor nipple. You can cap the other nipple on the actuators. It does not matter which actuator nipple is capped or connected to the MBC.

You need to open up your MBC adjustment all the way. Your boost should go down to 8psi. If not, something isn't right and you need to start inspecting your vacuum lines and verify the 3 actuators are still linked to the turbos.

If you do get your boost to go down to 8psi with the valve open, slowly close it bit by bit until it puts your boost where it should be (10psi).

Dave

Run a line from one of the two UIM nipples (one typically feeds the bolwoff valve) directly to the wg actuator, this will tell you how low a boost the wastegate will produce. If it makes 12 psi at 4500rpm then your wastegate or the hose to the wastegate is messed up, if it makes 8-9 at 4500rpm but hits 12 psi by 6500+rpm then you have creep and the wg porting sucked and/or your restrictor in the exhaust is not small enough. For your setup simply porting the wg should work to net 10 psi or so max boost (even a ported wg will sometimes result in more boost than spring presure which is usually 8 psi.

Re: nipple restrictors.

The 93 FD's didn't have restrictors in the nipples. Some of the 94's did, and I believe most (or all) of the 95's did. The restricted nipples replaced the "pills" in the wastegate and prespool lines. A restricted nipple simply had a much smaller hole in it than the non-restricted nipple. In order to lower boost with a restricted nipple, the hole must be drilled out. If you do this, make sure that you don't get any metal in your vacuum lines.

To Bypass the MBC, get a line and connect directly from the turbo nipple to the waste gate.


It really sounds like you just have a restricted nipple. As I have ran into this problem before on a few cars. And instead of drill, you can just T both Prespool and wastegate source together, then run that line to MBC, then to the waste gate.

If by passing the mbc gives you 8psi, then try the above what I said about T-ing both out sources from the turbo together, you can just a pluming T at from your local hardware store, get a Brass one.

Let Me know if that works for you, or if you don't under stand something I said.


He also mentioned he got "new" turbos, so I suspect that are from a new year. I have also ran into a few 93's with boost restrictor built into the nipple, including my 93... Although I don't know if the turbos were ever replaced.

Thats some good info though, I never thought of drilling it out for fear of getting metel shavings down the turbo.. and later sucked into my engine.

Ok I also noticed on my car, the previos owner didnt remove the pre-spool actuator when he went non-seq. So i still have 2 actuator, the pre-spool isnt hooked to anything but its all the way shut, would that make any difference performance wise?