My dealer did some work on my second owner 03 (no mods) to fix a prob where the original owner had messed with the vacuum lines for the BOV. My Evo has more power now, but under load there is a audible "wheeeeeeeeeeeeeee" I have no other Evo's to compare it to, are they supposed to whistle under boost?

I'm still showing 4-5psi low, I'm guessing this is probably a leak. I'm going to have to do a pressure test on it to see if another dealer trip is in the works.

 

That is your turbo, and it’s normal.

 

DO you have an aftermarket air intake? Is there still a top to you airbox? If you can see your air filter you will hear the BOV and/or the turbo 10x more than normal.

 

There are several possibilities for the cause of your problems. One is whether or not you have the correct vaccuum lines with the brass pills in them going from the boost solenoid to the turbo/wastegate. Another issue could be that the stock diverter valve may be leaking. I tested mine and it was leaking at anything over 14 psi. Then there is always the possibility of another leak somewhere in the system. What has been checked? Hope this helps,

Paul

 

What would be best would be for you to get to an evo meet or at least meet up with someone who owns an evo and has done some work on it themselves. It will most likely be much easier for someone with experience to fix it in person rather than over the net.

-Paul