I just had a new check valve put on today because the secondary wasnt holding boost, and now at 4500rpm the boost drops from 10 to 8ish and holds but continues to rev up with out gaining any speed. It slightly stutters during this. Any one know what this might be?

 

bump..

 

so ur saying it drops to 8 p/si and runs like that until redline ? or does it bump back up to 10 p/si ? do u see a stutter in the turbos or the engine ?

 

Probably ignition, get a new set of plugs

 

you might have a vacuum leak some where.

just look at all your vac hoses and see if there is a leak.

 

I have this happen often. I am still determining the exact cause but my theory is the CCA( Charge Control Actuator) That is in the Y-pipe. It flutters at the transition and doesn't want to open fully. I can get around this by 2 ways.....1) Chop the gas off then back on and it opens up.( not fun to do under WOT) OR..2) Rev till about 6k and shift early,stay above 4500 and the CCA opens and your flyin!!( I am anyways. ) As i said, I'm still searching and trying things.