Boost Issues...PLEASE HELP!!

[mkIImr2lvr]

Here's the history. The car was purchased about 1 1/2 years ago. It's a 1991 Turbo, that now has about 130K miles on it. The previous owner had put a MBC on it that he made using instruction off the "mr2.com" website. I noticed that no matter which way I turned the knob, I could not control the boost level. Sometimes it would only boost about 5psi, and then other times it would go all the way up to 11. Recently I've decided to figure out just what's wrong with it. Here's what I've done so far.

-With existing MBC hooked up, I took off the tvsv hose and capped it at the actuator. This resulted in no higher than 4.5psi with the mbc at full boost setting.
-I decided to take a chance and bought a Twos R Us MBC. I hooked it up and with the screw all the way in only got 6psi.
-I just got home and unhooked the hose from the compressor and capped it. I took it out and hit 9psi in 3rd and about 8.5psi in 4th.

So...what the heck is wrong?? I believe I have an exhaust manifold leak. Would this contribute to the low boost? Since I can't boost above 9psi, is it ok to leave the MBC off (and watch the boost gauge religiously)? Please help me any way you can because this has become VERY frustrating! Thanks

-Jeremy

[MR-355-5sfTe]

I'm not yet the expert on turbos... but an exhaust leak... especially around the manifold.... would cause a noticable loss of boost.
maybe I'm wrong though... like I said, I don't have much experience with forced induction.
good luck

[JekylandHyde]

An exhaust leak would definitely harm performance, especially when it is before the turbo.

[mkIImr2lvr]

Well, I believe I found it. While checking the exhaust manifold for cracks and leaks, I found a bolt that had been wedged in between the manifold and the block!! It must have been lodged there by the previous owner. When I pulled it out, it was covered in black soot. So, obviously it was the exhaust leak.

So, I'm going to replace both gaskets. (I found a small crack in the gasket from the manifold to the turbine.) I'm wondering if anybody knows if I can get the exhaust manifold off without taking off the turbo? The only thing I can see that would stop me is the 2 bolts on the underside of the flange from the manifold to the turbo. Does anybody know if it's possible? I'd like to replace these gaskets, but would rather not have to take off the turbo! Thanks for you help!

[JekylandHyde]

You said you found a crack in the gasket between the turbo and the manifold ... so you are going to have to take the turbo off the manifold to replace it anyway, so why try to avoidtaking it off?

*scratches head*

[mkIImr2lvr]

I was hoping I could just take the manifold off, and then replace both gaskets that way. But if I have to, I will take the turbo off as well.