I'm working on a friends evo and he installed the MAP EF4 with an anti-surge housing and Muse O2 external dump 18psi WGA. I'm also running ECU controlled boost with a GM 3 port. After it hits 18 lbs, its start fluttering like the wastegate is flapping open and close. We disconnected the 3 port and ran wastegate and it didn't do it all even up to 18 lbs.

Is this a tuning issue or what? It has an adjustable arm for the WGA. Could it be too tight? I've played with the WGDC tables in every direction to see if it would eliminate the flutter but no luck.

Any suggestions as to where to start?

 

It's normal. A restrictive pill could smooth things out but that depends on waste gate configuration. You're hearing the pulses of the solenoid. My tial ewg did the same thing on my tdo4 Subaru and same on my Evo with muse o2.

 

hey dude ,do you fix your problem.I have the same issue with you but 1.0bar I can hit for highest.
I think its because over boosting that causing hitting the boost cut even you have adj the boost limit to 319 .if you have figure it out pls let me know.