the sound seams to be coming from the bottom end and resonates in the oil pan. not looking good for me. I engaged the vct's and the noise was still present and i also pulled the coil wires one at a time and the noise didn't change which is wierd from what i heard it would change at the cylinder when you unplug it because it won't have as much force on the power stroke. So maybe the main bearing? I just put fresh fuel with some sea foam, but that didnt help at all. well heres the link...