Boost Problem

[ChvyKc]

I just got done installing my fmic and I am having problems holding more than 16 pounds of boost until redline. Boost will spike at about 20 pounds and go down to about 16-17. I have a Halman MBC and it is completely closed. I was able to hold around 22-23 pounds on my supra smic.

I had one thought about what it could be. My buddy was telling me that he was having the same problem with his car because the MBC was tapped off of the intake manifold instead of a boost source that was close to the turbo. Could this be my problem also? There are absolutely no boost source taps on the intercooler piping which is why I tapped off the manifold.

I am going to do a boost leak test tomorrow when I have a little more time but I thought that I would get some input before I start tearing the car back apart tomorrow.

 

[1bad92awd]

It could be a couple different things. Piping could be too large in diameter causing your boost pressure to drop or could be leaking someplace along the line. A boost leak test is a great place to start.

 

[ChvyKc]

Piping could be too large in diameter causing your boost pressure to drop...

It's definately not the size of the piping causing the problem. I was running 2.5" piping on my supra smic and was able to hold boost just fine. I didn't get a chance to do a boost leak on the car today though but hopefully tomorrow night after class. I really need to get this problem fixed (got a Mustang talking crap that I need to take care of at the track this weekend)