Should this be happening?

[Cool Mr Steve]

Ok, at any boost level above 9-10 psi, lets say for example 15 psi, my car hits 15-16 psi then wavers a bit and usually, not always but usually, falls lower and stays at a constant lower boost. I can be boosting at a full 15 psi most of the way through second, but when I hit third my boost rise to 15 then fall and remain at 12. This makes me sad Should this be happening, or is it a boost leak? (Which, btw, I have 2 boost leaks at the throttle body that ARE IN THE PROCESS of being fixed. I don't want 15 replies telling me to do a boost leak test, just some incentive to repair what I've found)

 

[4GSixty3]

2 things...

1. Vacuum hoses attached to MBC are too long causing boost spike.

2. MBC internals need to be replaced or the whole unit.

 

[doug]

And:

3. Stock T-25 turbo can't push 15PSI all the way to redline. It'll fall off a few PSI in the upper RPMs.

 

[KPWSerpiente]

^Just like he said.

If you are running the stock turbo (t25) the only fix is to get something larger. It cannot hold 15-16 lbs of boost to 7000 rpm.

-T