need help with boost problem
 

Running PFS PMC at 14 psi max boost. Initiation of secondary turbo is delayed. Primary boost is 14 psi to approx 4000 rpm. With pedal constant at wot, the boost drops off to approx 8 psi and engine falters. Sometimes secondary boost comes on - usually not. I can "trick" the secondary boost to come on by wot to approx 4000 rpm, then let up on pedal to activate charge relief, then quickly go to wot, and excess boost activates the secondary turbo and boost goes back up to 14 psi right up to 7500 rpm. If I shift quickly, the secondary boost stays on. Turbos are new, blueprinted and ceramic coated by Pettit. This problem was present before changing to the new turbos and developed suddenly- previously the boost pattern was 14 psi right up to redline. Where to look for vacuum leak first would help, so I don't have to check every inch of vacuum tubing for leak and check every solenoid til I find the culprit.
Ron A.

To check for vacuum leaks you can spray brake cleaner or BG spray around suspect areas. How much vacuum is your gauge showing? Go here for more help: https://www.rx7club.com/forum/showth...boost+problems

I'd try the 1/4 hoses that are between the charge relief and the UIM. Then inspect the hose between the blow off valve and the UIM. After that my next place would be to check to make sure the wastegate isn't stuck open. Make sure to check the "y" pipe also.