I had a TurboXS mbc on my car that I was borrowing from a friend because my electronic solenoid took a ****. It worked great never had any problems. Well he wants it back so I bought a hallman MBC used off a friend.

I installed it last night and it seems like its just boosting uncontrollably, I have it hooked up so the wastegate goes to the side fitting and the turbo goes to the bottom fitting which seems correct according to the hallman website.

So this morning I was driving to work and i figured I would see what it was doing so I stepped on it a little bit and it hit boost really fast and then made like a popping noise. I opened my hood and everything seems fine. The boost controller is all the way turned down so it shouldn't be boosting even close to that. I don't know what to do or how to figure out what's wrong with it.

Now it seems like my car is boosting all the time I'll be on the highway and barely touch the throttle and it will go into boost a little bit.

 

you need to get re-tuned for the mbc.

 

The ECU has nothing to do with the MBC not working correctly since it has no control over the amount of air passing through the MBC.

Do you have the bottom nipple running to the j-pipe and the side nipple to the wastegate for sure?

Take the MBC apart and make sure the thing isn't broken inside and that the ball/spring are ok.

Also, by turned down do you mean clockwise or counter clockwise?

 

Yeah I was about to take it apart, at first I thought they had the heavy spring it thats why it was boosting so high, but honestly it feels like my turbo is spinning faster than it ever has and that if i keep the throttle down itll just go forever.