Car won't boost past 8psi? Help needed.

[OldSchoolMotors]

Previously the car ran at 8psi stock with BCS, stock vacuum configuration.

Today I attempted to install a MBC in my friends 97 GST automatic, and failed.

I followed these instructions : http://www.dsmtuners.com/forums/articles-turbo-system-intercooler/237982-best-way-install-mbc.html

Took the car for a pull 8psi, adjust MBC, re-adjust MBC and still 8psi? I thought it was this POS MBC, so I threw my known working MBC inline, same thing 8psi?

Now I'm second guessing myself, so I just T into the BOV and run both MBC's that way, same thing 8psi?

At this point I looked at the Wastegate itself, with some pressure I could move it slightly and hear the flapper close, so it's not stuck open or closed.

BCS is completely removed and unplugged.

Any ideas? Thanks.

 

[turbotsi90]

mine was doing the same thing but mine ended up being the WGA. It was getting stuck

 

[Mr Peepers]

Do you know what style MBC it is? Bleeder/ball and spring? The installation is different.

Do you have any pictures or links to yours/his?

Also, ball and spring MBC's won't start changing boost until the screw is at a certain point, and quickly up the boost per turn after that.

 

[OldSchoolMotors]

Do you know what style MBC it is? Bleeder/ball and spring? The installation is different.

Do you have any pictures or links to yours/his?

Also, ball and spring MBC's won't start changing boost until the screw is at a certain point, and quickly up the boost per turn after that.

Well I can't speak for his MBC, but mine is a ball and spring brass type as pictured in install link. When I backed his MBC out, there was more like a needle, I didn't see a spring or ball?

What's this other way you speak of?

 

[Mr Peepers]

http://www.dsmtuners.com/forums/new...l-turbosmart-tee-style-bleeder-style-mbc.html

 

[OldSchoolMotors]

That is very helpful that is the type he has, thank you.

I used my spring and ball and no go, 8psi still

Going to try running WGA unplugged, see what happens.

 

[Mr Peepers]

Be VERY careful.

 

[Backinajiffy12]

WHat kind of boost controler do you have?

 

[vancitydsm]

check for turbo leaks, also what turbo is it? and how fresh is the turbo.. newish? oldish? check for turbine shaft play also plugged airfilter/ catalytic converter

 

[OldSchoolMotors]

T-25

I boost leak tested from the intercooler up, I will try to test it from the turbo now. Even with bad o-rings in a few of my turbo's I have been able to adjust the boost.

Would the WGA not opening or working properly cause it to run at a steady 8psi? Working correctly, it should boost up to 8psi on WGA.

 

[Mr Peepers]

How does the onset of boost behave? Shoot up to 8 around 3k and hold steady or get there kind of lazily by 5k? etc.

 

[OldSchoolMotors]

Ok I tried that link you gave me, and same results, the boost comes on as usual around 3k, sticks and holds for the most part.

.

 

[bling5tatus]

Why are you t'ing into the BOV line?

That's a terrible idea, I know that isn't going to fix your issue, but you need to pull your pressure source from somewhere other than the bov line.... like.... errrr.... ummmm.... compressor outlet elbow nipple, if you don't have one make one.

 

[Mr Peepers]

Post up some pics of how you have it set up, and pics and/or exact namestypes of the MBC's you are using.

Something to remember with a bleeder type MBC: Turning it to the left/loosening it will increase effective boost by bleeder off more air going to the WG.

p.s. your t25 has a nipple on the compressor housing, use it Leave the BOV line alone

 

[OldSchoolMotors]

Post up some pics of how you have it set up, and pics and/or exact namestypes of the MBC's you are using.

Something to remember with a bleeder type MBC: Turning it to the left/loosening it will increase effective boost by bleeder off more air going to the WG.

p.s. your t25 has a nipple on the compressor housing, use it Leave the BOV line alone

I'll try to get a pic up, I only went to the BOV vacuum setup as a last ditch effort to get it to work, previous to that I ran it from the compressor nipple to MBC, MBC to wastegate actuator, see original post.

Post pics soon.

 

[da_reeseboy]

Just curious, is it the stock BOV? I have a Greddy, and after the last time we pulled my tranny we accidentally put the vacuum line to the wrong nipple on the BOV and all of a sudden I was only seeing 9-10 psi instead of the normal 20-ish (oops).

 

[Boostin95RST]

where in the cleveland area do you live. if its not to far maybe i could check it out in person. i live iin twinsburg, oh. im off work tomorrow so let me know. hey im not a pro but another set of eyes/hands could always help on a dsm