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I replaced my vf11 with a low mileage TD04. The vf11 use to boost at 11-12psi until 5250-5500RPM.
Now, with the TD04, and a MBC, a have a hard time getting 10-12psi, i adjusted the MBC to higher settings, i get 12psi for about 200rpm@ 3500rpm then it drops fast to 6-7psi until 6000rpm.
The only thing i did not use in the wastegate and MBC plumbing is the small plastic restrictor use with the vf11, is that the problem?

If i go straight to the wastegate, how much psi should i get, stock wastegate pressure?. I get 6-7psi with my mbc at the lowest.

The stock waste gate is set at 9psi, but I am having the same problem only getting about 5psi at all rp ranges. But looking around I have seen numerous acounts of 3000gt guys boosting to 15psi with the td04. She is capable but how to get it I have no clue.

there is a way with the mbc but i cant explain it, if you get a electronic one you can bring it up no problemos. mbcs are crap i had so many of them never did like them.

You need the restrictor.

Yeah, i'll try to put back the restrictor a.s.a.p., i'll let you know

oo. maybe thats what is happening with my turbo. its the stock one but i took off the restrictor.....

Any results yet? Have you put the restrictor back?

the restrictor is the piece kind of like a reducer right? one side is smaller than the other? is the smaller hose the one that connects to the wastegate? i might have it backwards.

i put on the reducer/restrictor and the boost does hold now for me. but it was weird, i was doing a second gear pull and the psi shot up to 10, then went down to about 7 at 4k rpm, then shot up to 12 when i started letting off. maybe i have it backwards. the smaller hose is supposed to be on the wastegate? anyone can help with that? thanks!

UPDATE: doing the same thing now. doesnt hold boost. bah its annoying. i get smoked by a lotta things so easily this way!

Restrictor back on and still doesnt hold boost. It jumps to 12psi than goes back down to 6-7psi.

I did put the restrictor before the mbc, i'll try with the restrictor after the mbc.

I just don't feel like buying an electronic boost ctrler, and it use to work good with the vf11, i'll let you guys know

i tossed that restricter thing away 13 years ago. mbc are crap mhrallyteam.

if you do get a electronic one get a turbo smart, i had greddy, hks, turbo-xs, there all crap. turbo smart e-boost, you can set lows highs mids its crazy what it does.

weird. i have a restrictor before AND after the MBC. anyone know which sides they supposed to be on? imma mess with it some more tomorrow. will let ya'lls know.

Ok, i replaced my mbc with and other one laying around at the shop, and placed the restrictor before the mbc, everything is running smooth now. I guess the old mbc leaked somehow.

Anyway, i think i'll put the restrictor after the mbc anyway, it makes more sense to me, but for now i'm back to 12psi troughout the rpm range, such a sweet feeling

ahh. maybe i have a leaky mbc too. i will check on dat. thanks for the update!

NICO I WRX U wrote: mbc are crap mhrallyteam.

They say, a bad workman always blames his tools.

hahahaha 555BCTurbo.

the vent in your MBC might be to big for the actuator you're using.

I encountered this problem with my DIY MBC. I installed it and it was pushing 14 peak and would hold a solid 11 through all gears. I then turned it down a bit for a DD setup while not pushing to old turbo too hard and all of a sudden it will peak at most 12 and drop to 6 no matter what i do. I figure it was the brass BB i was using that was not seating properly, so i just pulled it out.

So my question is with these DIY controlers is there supposed to be a vent hole on the wastegate side? How big? What does it do

Also i was thinking about using some liquid gasket to fill the end cap where the BB would normaly go, put the spring in and let it set, then pull it out and trim it up so that it would be like a rubber stopper. I think this would be much more reliable than a BB at sealing. What do you guys think?

I was also thinking that the main cause of MBC's sucking is the fact that the initial force required to open that valve is much more than it takes to keep it open so would that explain the boost drop?

You do usually want a vent hole on the outlet side. I usually drill a 1mm hole. This relieves pressure in the actuator when the valve is closed.

Potentially better than a simple vent hole would be a check valve plumbed back to the inlet of the MBC.

In my experience a stainless steel ball bearing seals very well against a brass seat. Get a stainless BB and use a hammer and drift to press out a seat in the brass nipple in the exact shape of the BB.