I am having an issue with what seems like my turbo, or something connected to it. Stock 09 wrx turbo setup, with a catted dp and stage 2 tune. I am having an issue where I can hear the turbo fan spinning, like a lot. It is consistent with RPMs and road speed, not necessarily boost pressure. When I take my foot off the accelerator and clutch in, is when I hear it the most (as the RPMs drop off to idle). It sounds like the fan is just spinning under its own momentum. I first thought it was due to one of the bolts, connecting IC to turbo, being loose, due to stripped threads. Dealership helicoiled the threads and the IC is secured now. Noise still happens
My plan is to hook up a tactrix cable this weekend to see whats going on. According to my butt dyno, the car is still boosting well and driving normally.
Also, I know exhaust gasses pass through the turbo constantly, right? When letting off the accelerator, does it normally spin under its own momentum to idle speed or does something control its slowing down?