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Q&A regarding engines, turbos, and intercoolers and power upgrades
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turbosmart mbc...need help

Thu Oct 07, 2004 3:12 pm

anyone installed this boost controller??i was hitting 6psi on first gear before i installed the mbc..and 9psi max..after i installed this boost controller in my car yesterday..i noticed that im way over boosting...i test drove the car after installing it...and on 2nd gear...i was at 15psi@3000rpm...and i hit 20psi@5000rpm...and hit the fuel cut...at idle..and revving it to 6000rpm..i would get 10psi...i checked all the hose and connections for cracks or splits..or for anything lose..but couldn't find nothing...i disconnected the turbo vsv...and it's still the same....what could be the problem here??could the mbc be defected??need help...i can't even enjoy my car right now..cuz everytime i try to gun it...all i get is fuel cut...
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Thu Oct 07, 2004 4:23 pm

Have you tried adjusting it yet?

Thu Oct 07, 2004 5:38 pm

yeah..i tried...played around with it...and boost is still high...im scared to floor it now...just the feeling of fuel cut is not nice...

Thu Oct 07, 2004 5:44 pm

How did you hit 20 psi without hitting fuel cut?

Thu Oct 07, 2004 5:46 pm

where do you have the vaccum hose connected to?

Thu Oct 07, 2004 6:37 pm

turbo+mbc+wastegate actuator.....that's what it said on the diagram that the boost controller came with....

hitting 20psi w/o fuel cut???i seriously dont know...because i thought the the ct26 can only hold up to 15....but as soon as i hit 20....that's when i hit fuel cut...

Thu Oct 07, 2004 6:48 pm

It might possibly be hooked up backwards? I would try reversing the lines, like taking the one you hooked up to the turbo and hooking it up to the WG actuator and vice versa. By the sounds of it it couldnt hurt.

Thu Oct 07, 2004 6:53 pm

umm..i dunno about that...there's an arrow on the mbc that tells you where to hook it up to...im pretty sure i did it right..unless they marked the arrow wrong.....

Fri Oct 08, 2004 2:01 am

spoolin_gt wrote:turbo+mbc+wastegate actuator.....that's what it said on the diagram that the boost controller came with....

hitting 20psi w/o fuel cut???i seriously dont know...because i thought the the ct26 can only hold up to 15....but as soon as i hit 20....that's when i hit fuel cut...


Where is the end that isn't connected to the bc at?

If you're hitting 20 psi for a fuel cut, you either have a modded ecu, or a problem. Or a adjustable fcd.

Fri Oct 08, 2004 4:56 am

Yea! that sure is weird. I thought that the usdm st185 get boost cut at 12psi and the jdm rc model gets it at 18psi. Isn't that right you guys?

Fri Oct 08, 2004 10:53 am

I have the same MBC on mine. I' ve also notice much overboost since before. In cold winter days i've seen often a drop of 1.5 to 1.1 bar. Maybe there is a flow restriction to actuator and this cause so much overboost.

Fri Oct 08, 2004 1:27 pm

alltracman78 wrote:
spoolin_gt wrote:turbo+mbc+wastegate actuator.....that's what it said on the diagram that the boost controller came with....

hitting 20psi w/o fuel cut???i seriously dont know...because i thought the the ct26 can only hold up to 15....but as soon as i hit 20....that's when i hit fuel cut...


Where is the end that isn't connected to the bc at?

If you're hitting 20 psi for a fuel cut, you either have a modded ecu, or a problem. Or a adjustable fcd.



what do you mean by the end that isn't connected to the bc???the boost controller is in between the turbo and the wastegate...and both ends are connected...

Fri Oct 08, 2004 1:41 pm

http://www.twosrus.com/new/Lower_Frames ... ctions.PDF

See if the link above w/ instructions will help. It's for an mbc install on a ct26.

Fri Oct 08, 2004 2:00 pm

im not asking for instructions to install the bc...i installed it right....i just want to know if anyone else experienced this...as for now..i took it out....i dont wanna risk anything...boosting at 9 again.....great gts...how much boost were you putting out before the mbc??and after????thanks...

Fri Oct 08, 2004 2:09 pm

spoolin_gt wrote:im not asking for instructions to install the bc...i installed it right....i just want to know if anyone else experienced this...as for now..i took it out....i dont wanna risk anything...boosting at 9 again.....great gts...how much boost were you putting out before the mbc??and after????thanks...

I was between 1.1 - 0.9 bar.....
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