Hey i have a Evo 4 and ill been having trouble with free boosting.
the car is quiet stock 3" tbe, Intake, 2.5" Intercooler piping with a 600x300 FMIC

The problem is with no Manuel Boost Controller its running 12Psi.
But when I add a boost controller it free boosts. (past 20Psi)
No matter what the boost setting is at.
I have tried 2 different Boost Controllers and still the same.

has this ever happen to anyone before or no what would be causing this?

Thanks

 

I would have said faulty boost controller, cause all a manual boost controller does is restrict the airflow to the wastegate. But you have tried multiple controllers

You could possibly have a faulty wastegate spring/actuator. As to go about diagnosing that, I'm not sure what is involved I personally haven't encountered that.

 

Thanks I was thinking that as the actuator doesn't look to be in the best shape.
So might Just do the swap to external wastegate.

cheers

 

Odd question, but where is your boost gauge taking this reading?

 

how many miles on the turbo and wg? try a 3-port?

 

or, get a new higher pressure wg. my turbosmart with 21 psi spring works great!