I have a 2012 Kia Forte with the 2.0, it has around 102k miles. This sound has been plaguing the car for around 10k miles, it is a whistle noise that doesn't change with RPMs, constant whistle. I've tried to track it down, initially thought I had a vacuum leak, but I checked all of the hoses, have tried the smoke test for the vacuum, nothing. When I put my ear up to it, it almost sounds like the fuel rail is whining, the sound is the loudest on the right side of the engine (facing the engine from the front of the car), but the left side also whistles a slight bit. I've found a few other people on the forum who have very similar complaints, they just didn't get any answers. I'm wondering if anyone has figured out what this phantom whistle is. The only other thing I can think is a loose bold on the manifold? Who knows. It doesn't affect performance, it runs smooth and there are no other abnormal noises (at least in Forte terms, I have the notorious piston slap that I got to quiet down a ton by adding Schaefers Moly EP). Thank you guys! I'll upload a video link to my issue. Maybe we can figure this out haha.