well here it goes, got my defi boost gauge with autometer single pod and hallman mbc from lancershop a couple days ago and finally got around to installing them with my buddy today...we installed the pod and gauge first, everything went great perfect fitment, no problems, took it for a test run, spiked to almost 20 psi then tapered to about 16 or so...then took a break to eat when back out to do the mbc..hooked the vaccum line from the side of the mbc into the wastgate actuator and from the bottom of the mbc i t'd it off from the intake manifold and capped off the nipple from the turbine nipple, took it for a drive, only hit 12 psi, nothing more, spooled quickly as well...then decided to connect the vaccum line that was on the bottom of the mbc to nipple on the turbine and cap off the t that we used on the intake manifold temporarily, took it for a test spin...still 12 psi, we fiddled around with all kinds of irrelevant things, but cannot figure it out, will someone please help me diagnose this problem....i put it back to stock and the boost gauge is reading normal once again...
thanks ian

 

anybody...i know its late...

 

Well, it should read 11-12psi if the MBC is turned all the way out. Did you ever turn the MBC knob to raise the boost? What boost were you expecting to see?

When you install an MBC, you always put it at its lowest setting first, then test it. After you confirm it's only 11-12psi (base wastegate pressure), you then start turning the knob in increments and re-testing until you get the boost to the desired level. With the Hallman, it will take many rotations before you get to 21psi, or whatever boost you plan to run. It will probably take at least 4-5 rotations before you even start to see it rise above 12psi, so don't fret.

Did you just install it, test it, and never turn the knob?

 

i installed it then turned the knob a few rotations still the same boost...should i turn it a whole bunch of rotations....

 

with the hallman it takes a while to get into the boost. so keep on turing until u see boost. this is how i hit fuel cut for the first time.

 

if this is the problem i will be so relieved, about how many times should i turn it before i see it come out of preset, im gonna reinstall it tomorrow night...we spent hours trying to figure out the problem....thanks alot guys

 

so how much should i turn it to notice a change in boost...?

 

The way you had it hooked up first time is the same way i have mine hooked up right now. I started doing pulls with it turned all the way down and boosted 15 psi with the heavy spring and the Forge UNOS. Took me about 8 pulls and SEVERAL turns to get it to hold a solid 21psi. Keep trying, i'm sure you're doing it right. If you're at 12psi, don't be affraid to turn the dang thing more than once before trying another pull. I turned mine 2-3 clicks on about my 4th or 5th pull once i figured out how much one click was worth in PSI.

 

Damn, just go try it. We told you the problem and many people before you have made this same mistake. You had it right the whole time, but never bothered to turn the knob enough. YOu keep turning until the boost goes up. If you go all the way down to max boost, and it still reads 11-12psi, then you know something is wrong. It would have been much easier to do this simple troubleshooting step rather than uninstall and post on here for help. Use your noggin', bro'!

 

sometimes going straight to the point is the only answer... thank you for clearing up the rest of our hesitance

 

haha....yeah it prolly bugs u guys, i had to work all the day so its all i could think about..im gonna put it back on in the morning
thanks

 

https://www.evolutionm.net/forums/sh...d.php?t=116017

 

thanks...

 

When I put my hallman mbc in i had it turned as far in as possible and was still only hitting 17psi max.

I put the stiffer spring that came with it in and started the testing over again. That solved the issue.

 

That would indicate a problem in the installation, the seating of the spring, your WGA, your boost gauge, or some other leak somewhere. I can run over 25psi on my Hallman Pro with the regular, base spring.