Quick backstory that may or may not related. I'm at 146k miles with no issues besides burning some oil and still have the original turbo. Yesterday I screwed up driving while low on oil. I hadn't driven the Evo in awhile but I was aware the oil level was a bit low. I usually change my oil every 1500 but I was well past this time around. I was driving on the highway in 5th gear on WOT when the car started make a heavy vibrating noise and wouldn't accelerate on WOT. Expecting the worst I changed the oil and check the intake side of the turbo. Oil was about 3/4 full but no metal objects or anything unusual. Compressor wheel looked fine and no play in the shaft.

Right now the car runs, idles fine, and can slowly rev to +6000 rpms with no issues. Ran the scanner and no codes either. However as soon as it reaches around 7 psi it starts making the same heavy vibrating noise and has trouble building any more boost. It sounds like when you're on the highway and you drive slightly off the road on to those ridges that alert you you're out of your lane. I was going to lift up and check out the turbine side but I'm honestly unsure what to do next. I'm hoping its turbo related but the loud noise has me worried it could be something in the engine. Any help would be appreciated. Thanks.

 

hummmmm....

i would jack it up... crawl under the car... make sure nothing loose in the drive train.
axles, driveshaft, wheel bearings, etc.

then i would just start taking stuff apart and checking

pull intake off, look in turbo, make sure no crazy play.

compression test
boost leak test
pull valve cover off and make sure all is well with valvetrain
check timing

etc. etc

 

Waste gate Or maybe blow off valve oscillating? What type of boost control are you using ?

 

Do you have a wide band afr gage? This could also be heavy knock if it’s running lean. The ecu might be pulling timing and boost to try and save the motor.