I've installed my Hallman MBC for over a year now, and had no problem with it until recently. I set my boost at 22psi (temp. was about 70F) and left the car in the garage for 2 weeks with MBC untouched. Today I took the car for a spin (65F outside) and tried 3rd gear WOT after driving around for 15 minutes. The boost spiked to 27-28psi for a split second before I let off the gas.
Could it be my MBC or the lines are leaking?
Should I have to worry about my motor? The car is tuned and I have full tank of 100octane. The knock sensor on my UTEC didn't show any sign of knock.

 

bump

 

If all the lines are hooked up correctly and not leaking, the only boost problems a MBC can cause is lowered boost levels, unless you calibrated it while it was sticking, turning it up too much.

I had my hallman for 1 year and twice my boost dropped to 14 psi (min boost with wastegate fully commanded open) and wouldn't go any higher, it was my hallman. To fix this I just turned the MBC 1/4 turn this way and that way to reseat the stuck ball.

Sounds like a loose wastegate command line, stuck wastegate (I don't know if that can happen), or most likely your MBC is now functioning properly and just need to turn it down because you turned it up too high when it was sticking open.

I'm thinking of buying the forge MBC now because of this.

If you start the car and it runs, you probably didn't hurt anything. Just dont let it go that high again till you got alky inj.

 

Bump

Anyone else know what can cause a 7 psi boost spike for no reason?

 

see if u can take it apart and clean it, might be stuck all the way open.

 

I had a ams mbc and it would spike.I bought the hallman pro and does not spike.I would clean it or replace it.