I have a built EVO 9 with a 2.2, ported head, AEM, and AMS 35 R kit. I am having a problem with a boost spike of 7 psi at 5600 rpm.
I have changed the turbo, waste gate, waste gate spring, boost controller, map, map sensor. I have run out of ideas. The spike is there no matter what the boost is set at, and is always at 5600 rpm.

Someone help!

Thanks.

 

is it a boost spike or are you tapering boost?

S

 

Its a spike. I get full boost at 4000 rpm (20 psi) it wil hold that boost perfectly until it gets to 5500 rpm where it will drop slightly and shoot up to 27 psi and drop back down to 20 psi at 6000 rpm and hold that to the limiter.