To confirm my suspicions, I just finished putting a Defi-D boost gauge on my 03 Evo. My Evo has been feeling weak, especially in the mid range on up. My new boost gauge is telling me (unless I hosed the install) that it is seeing a max of 11psi. While under the hood, I saw that the clamp for the boost recirculation thing was loose, so I tightened it. I was hoping that it was the source of my problems, but now I don't know what to think.

I have been noticing that I can clearly hear the stock BOV. And when doing things like revving it up about 3500-4k in 4th it sounds like it may be blowing off boost while I'm on the gas.

With my warranty running down, I guess I'm headed for the dealer.

 

double check all the connections where you taped for the boost gauge. what did you tap into to install the gauge?

 

I did this install:

https://www.evolutionm.net/forums/sh...ad.php?t=98114

I did the plastic ties nice and tight on the hose connections, I went out and double checked everything. I didn't find any binding anywhere on the hose to the intake. The guage is very responsive to throttle inputs.

It runs 19psi vacuum at idle. I have driven it some since the install, and have seen the boost drop a few times without explanation under light load, right before I lift. The car was already due to go to the dealer for a mystery brake warning light. I have seen the brake light come on when the boost drops (the light comes sometimes with a throttle lift); I could be looking at a vacuum leak. I'm probably going to take it to the dealer on Monday morning.