I currently own a 2001 Evo VII RSII, it has 125xxxkm on it and is fully stock aside from a gutted cat and hks catback.

about 2 weeks ago i started my car and it felt like it didnt want to go anywhere, it got it out on the road and there was a very loud whining noise, after driving for a while i accelerated at a light and it felt like the car overrevved and then lost ALL BOOST, apexi gauge will not read above 0, other than that the car drives perfectly fine, just the turbo will not build boost.

What i have tried so far:
-checked all couplers and fittings all seamed fine no rips, not popped off
-pinned the wastegate flapper open and closed (no change)
-removed and hollowed out cat (have heard clogged cat can cause no boost)
-replaced camshaft position sensor as i was getting a code for that (am not anymore but still no boost)
-have removed battery for 10 minutes, car is not in limp home mode
-no check engine lights
-reading acd/ayc pump failure, but that was ther for over 5000km before the i stopped producing boost.
-removed intake and checked turbo, spins freely, no shaft play.
what could be the issue here????

i dont think it is a boost leak as car revs up to 7000rpm just fine no cuts

have had the car in the shop and they couldnt figure out why either.
have an appointment scheduled for march 14th with mitsu "triple diamond master tech" hoping someone on here can help me figure it out before then so im not charged an arm and a leg to liekly be told stuff i already know

 

Just a visual check? Have you done a BLT to verify that the system, beyond just the charge piping, can hold pressure?

 

Have not done a BLT yet, will be getting that done this thurs, but wouldn't a boost leak large enough to cause a no boost scenario cause rough idling, predetonation, running rich, etc the car drives perfectly fine aside from the fact the im not able to get above atmosphere

 

Sure. It's still one of the very first things I would do, just to cover that base. I do agree with your logic though.

So you have a car that runs/drives, and you can accelerate under load to 7K rpm with the WG wired shut, having eliminated any potential exhaust restriction or leak between exhaust valve and turbine inlet, and not generate enough flow or shaft speed to build any boost?

 

Boost leak test it for sure. I don't quite understand the overrev comment, but it may be related. If the intake manifold or throttle body gasket blew out in a big way, it would cause a big boost leak, and would be letting in a ton of air under vacuum, so it could rev high at 0% throttle. Could be a bigger vacuum hose that came off, too.