MBC Question - How to use it properly?

[gtrej01]

Ok, I have searched and have found no straight answer as in how to properly use an mbc.

I have a Perrin MBC as pictured below. I connected the bottom end (red side) to the j pipe off the turbo and the top side (grey side) to the wastegate. I believe this is the correct way to connect it if not someone please correct me.

I have it connected as stated and took the car out for a spin and the boost creeps past 20psi. I have it almost maxed out to where it is completely closed, probably about 1 turn and a 1/2 away. I opened it more and the same happened.

I have yet to do a boost leak test, would this be the cause of it creeping? If so back to my original question? How do I set the MBC to the right boost level i want..I would like to have it at 15 psi.

Any help is appreciated. i am trying to understand the overall concepts better.

 

[JuGs]

well that sounds correct. Worst case if it dont work just flip it around.

 

[mantega4g63]

well that sounds correct. Worst case if it dont work just flip it around.

Flipping it around does absolutely nothing. That's the same as having your jpipe hooked straight to the actuator, except with more restriction. I recently flipped mine around because the guy before me had it backwards, and I am getting the same problems as you. I also hear vacuum leak while boost, all I want is 12psi and I'm getting 15 BEFORE fuel cut, I'd hate to see what I get if I didn't fuel cut.

http://www.dsmtuners.com/forums/art...255354-another-proper-mbc-hookup-diagram.html

If the boost source isn't pushing the spring up on the bottom of the controller, then I don't see how it could possibly function properly.

 

[jrohner]

Sure you're not just getting the very common boost creep which has nothing to do with a boost controller?

 

[gtrej01]

The spring and ball are brand new.

I am planning on making my own boost leak tester tonight and checking for leaks.

Just want the damn car running right. Thanks

 

[gtrej01]

The spring and ball are brand new.

I am planning on making my own boost leak tester tonight and checking for leaks.

Just want the damn car running right. Thanks

Ok so I found some useful information on the Perrin MBC.

COMMON QUESTIONS:
• My car’s boost is spiking- Boost controller is set too tight, Boost controller is hooked up backwards, or possibly a factory
restrictor is placed in boost hose.
• My car’s boost is too low- Boost controller is set too loose, or boost controller may be hooked up to the factory tee, not like
the diagram shows.
• I can’t get more than my desired amount- This can be caused by the turbo being too small to be able to hold the desired
boost, or boost leak in the boost system.

Also:

ADJUSTMENT AND TUNING:
1) Loosen adjustment on controller until 5 grooves are visible(making it longer). The 5th groove on shaft should be aligned with body. This is
the minimum boost setting and is the farthest amount the boost controller should ever be unscrewed. NOTE: MINIMUM SETTING ON PERRIN
MANUAL BOOST CONTROLLER WILL EQUAL THE BOOST LEVEL SET BY SPRING IN ACTUATOR. BOOST CAN BE ADDED BUT IT CANNOT BE
REDUCED TO A VALUE LOWER THAN THAT! NOTE: Do not disassemble controller as damage to internal seals may result!
2) Each complete revolution (making it shorter) of adjustment will equal approx. 1.5 lbs increase in boost. Be sure to disconnect the vacuum
hose every time you adjust the boost controller. A twist in the vacuum line can affect boost stability.
3) The controller can allow 30 PSI or more boost on most vehicles. Your vehicle may be higher or lower than that level depending on the
wastegate spring and size of turbo charger. Consult a professional tuner to decide which boost level is correct.
4) Road test after each adjustment until desired boost level is achieved. Make sure when testing boost level, that 3rd gear or higher is used. If
1st or 2nd is used, boost in higher gears will be too high and cause engine damage.

Very useful, I will try these settings when I get home.