I have a strange problem with my Evo. When I first start it up and drive it for a while (this while can range from five minutes to half an hour) it wont make consistent boost under wide open throttle. Some times the car wont even make over 11 psi, other times 17ish psi is where it gets stuck. Then just randomly I'll go WOT again and the car will make full boost (about 25 psi) and after that it's fine for the rest of the drive. It'll make full and consistent boost every time after it hits that max boost once. It's a very unsettling and annoying issue as I don't know if I'll have the power until it's happened at least the once.

Relevant mod list:
Forge wastegate actuator that is basically brand new (have replaced with a stock one to test and it still does it) with preload set to 14.7 psi, the stock Evo 4 boost
Evo IX turbo with less than 10k KMs on it
AEM truboost EBC

I have checked for boost leaks. The system holds pressure at 30 psi for about 40 seconds with a noticeable leak through the throttle body seals. Everything else is fine. T-bolt clamps are great in that regard.

Just to rehash and simplify; order of events of my problem:
Start car
Drive for a bit to let it warm up
Go WOT, car wont make anywhere near target boost, and sometimes well under wastegate spring pressure
Continue to try out of frustration
Eventually on a random WOT pull the car will start working properly and hit target psi of about 25
After it hits the target psi once it will always make target boost every single attempt after it until I go to drive the car again

Doesn't seem to matter if the motor is hot or cold.
Thought it was possibly a wastegate actuator issue and an EBC issue. I don't see how it could be either though, as if it was a boost controller issue it would get stuck at wastegate pressure, not 5 psi below it.

If there is any info you feel I am missing, or if something is explained poorly, please ask me to reiterate and I'll try to explain it best.

Thanks for any potential help!

 

Subsitute the BOV.

Have you ruled out it being a Ecu control?

 

+1

try removing the bov and shut that hole.
if the issue is solved, its ur bov.
ignore the turbo flutter sound when trying this or else u'll have the urge to leave it that way

 

I would have to agree after rereading your post with checking the bov ^^

 

Is your car tuned to limit boost until you are up to operating temp?

 

Hey man did you ever figure out your boost problem? Im having the same issue and can't figure it out, all th threads I've seen never report back.