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Post by mister2mkii on Jun 29, 2005 19:23:30 GMT -5
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
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Post by 4g63ownedu on Jun 30, 2005 9:14:15 GMT -5
I had a similiar problem when i first got my mbc. Turns out I simply had mine hooked up wrong. I think you have a vaccum leak somewhere. If your getting unmetered air going into the rngine it will kill boost and your horsepower. Check all your hosing for corrosion, as I saw Chris had a nasty hole in his intake pipe from the plastic rotting away. Check your intercooler hosing and the intercooler itself. Also check all the couplings and connecters that they are tight. If your leaking at the exhaust mani you should see some black build up around the leak. Also check the turbo for leakage and shaft play, if it's dying that could be a big part of it. If all else fails take it to the dealer and pay an hours labor for a diagnostic. I've had to do that a couple times and though it costs some money it's saved me a lot of time and hardship and the fix was simple enough to do myself.
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Post by mister2mkii on Jun 30, 2005 13:23:42 GMT -5
Well, I'm gonna check the ex. mani for any leaks. Then maybe see if there's any loose hoses or anything anywhere. It might be the turbo just dying...but i sure hope not.
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Post by 4g63ownedu on Jun 30, 2005 13:26:56 GMT -5
Who cares, it would be a good excuse to get a better one.
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Post by Töuge-MR on Jun 30, 2005 14:09:25 GMT -5
Well i already told you what i think. I took a ride in it and watched boost pressures.. I personally think your wastegate is stuck open. I guess only time and screwing around with vaccum lines will tell.
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Post by mister2mkii on Jul 1, 2005 9:48:24 GMT -5
I wouldn't care about the turbo dying if I weren't going to school. My bank account will be in the negative come next spring!
And for the wastegate being stuck open...I might try and check that one of these days. It'd have to be only stuck half way open, b/c otherwise I wouldn't make any boost. But since I'm now making 9psi....I'm not so sure if that's the problem. But chris...you are more than welcome to come help me out next week!
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Post by Töuge-MR on Jul 3, 2005 2:20:10 GMT -5
No, youl still make boost with it open.
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Post by 4g63ownedu on Jul 3, 2005 10:34:44 GMT -5
Just depends on how much the gate is open. If it were open all the way you wouldn't make hardly any boost. It could be one of several things. I'll call you tomorrow and we'll get together and check it out than we can hang out and get some grub.
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Post by mister2mkii on Jul 7, 2005 0:17:59 GMT -5
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!
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Post by toophatspitfire on Jul 7, 2005 1:49:01 GMT -5
i would help, but i dont know how to work on spare tires in engine bays...
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Post by 4g63ownedu on Jul 7, 2005 17:43:56 GMT -5
LOL! You'll need to take off the turbo to get the manifold off.
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