This is my first winter owning a diesel, and we got down below freezing up here. On my way to work, I noticed during accelerating and cruising that the sound of the motor would change, and the engine speed would drop down. It would go away if I accelerated harder. On the way home it drove like normal.
I don't have a full exhaust done yet (it's stock) but I could hear it sound different through my cold air intake.
Here is a video of me driving.
From other videos i've watched, EBPV noise sounds like a high pitched hissing noise through the tailpipe, and happens at idle too. Mine wasn't happening at idle, but from 1200-1800 rpm it seemed.
Could this also be symptoms of a failing Cam Position Sensor? I've got one in the glovebox...