So I have a 2003 wrx with 63,000 miles on it. I've owned it for about two months now. I've started to notice a noise coming from the engine that is kind of like a knock/fluttering kind of noise. It seems to only happen when I give the car gas. I parked next to a wall (facing the drivers side, window down) where it would amplify the sound, and when I gave it gas it sounded like the pistons were rubbing or something... Again, kind of like they're fluttering. The noise becomes noticeable at 2000 RPM and dies off as the RPM's drop.
This guy looked like he had a similar problem but never got an answer:
fluttering noise in front left area 02 WRX
My car is bone stock. The only thing I have done recently was I tried the Rotella T6 5W40 oil and Bosch oil filter about 750 miles ago. The sound was not there before I did the oil change. I'm a little suspicious that maybe the Rotella T6 isn't agreeing with my car, but it don't really wanna blame the oil. I'm wondering if it might be the infamous waste gate flutter that I've read about. If that is the case, can anybody explain how I can diagnose that it's the waste gate?
I apologize that I'm kind of beating a dead horse with a stick over this "noise" problem, but a lot of info out there is pretty dated.
Thanks guys! P.S. this is not the lifter ticking kind of noise.