Im stumped...04 with 36kmi, stock (original) turbo, 9.8 and everything. the noise is like a howl that i hear at about 5" vacuum and lower, and continues through boost and is just slightly audible throughout. can be heard with windows down or up. the pitch starts lower and gets higher as i either give more throttle or just ease up the rpm. i feel like the howl is more directly related to throttle because it changes pitch as i push and release the gas, and does not reamain after i release it. the noise does not go away after any period of driving...i have driven for 30 min or so nonstop and can still hear it upon accel. this sounds strange but i noticed the noise after i changed the oil last week...no difference in oil or filter i always use. im prepared to hear the list of usual suspects so before that happens...I blew my t-case about 10kmi ago, it was replaced with a new one. I am familiar with the noise a failing TC makes, and this is not it. also, i have had boost leaks in the past and that is not the noise i am hearing. I also took my intake off yesterday...to my surprise, there is NO shaft play at all...it feels and looks like a brand new turbo...no oil, no scratches in comp housing. for these reasons, im totally stumped...
-my most recent mods are UICP and koyo radiator
- other mods are tbe, cone filter and ss maf pipe, licp, ets fmic, 255 fp, port/polish ex mani, ss o2 house...no cams
-dont know if it matters, but im untuned for fmic and pipes, o2 house and p/p mani..wanted to put all pieces on before i got tuned. ive been untuned for these pieces for about 5 wks total..nothing unusual until now...but like i said the noise didnt appear until i changed the oil, as wierd as that sounds. the oil level is normal, and i even topped it off with a bit for good measure.
I tried to keep this short...let me know if i left out any general info...thanks everyone

 

someone's gotta have an opinion...no shaft play and its not TC

 

what is this more of an Evo General type question?

 

That wont really matter....If you think this is a Evo Engine/ Turbo/ Drivetrain issue, then this would be the correct place for this.

To try and help your situation, have you done a boost leak test? could be a leak somewhere along your charge pipes that whistles at a higher pitch under acceleration. However, it does sound like an issue with your turbo. Does it still spool up and hit full boost normally?

You might want to have your tuner check it out. Could be something with an easy fix that's not easily described.

 

BOV leak?

 

or ic pipe leak??

 

Yea, that's what I meant by charge pipes.

 

i dunno guys...ive had leaks between my turbo outlet and licp and in my uicp at the recirc hose on separate occasions. both have been corrected, and this noise is nothing at all like those leaks. it doesnt have a whistling or air leak quality to it. it seriously sounds like the turbo is gonna die but i dont see why the sound would be the only symptom, while the turbo components seem completely healthy physically...thanks for the suggestions tho, ill check all connections again, however, they were all secured and re-secured before i started the thread

 

i tightened the hell out of all pipe couplers and bov connections...still same sound

 

check for an exhaust leak on 02 housing and mani...
Mine did the same and it turned out that one of the bolts holding 02 housing came loose.

when the car heated up the noise went away!