I have a 2012 QX 56 that may have major engine failure but looking for other opinions. Current working theory: The high pressure fuel lifter bucket failed (OBD Codes P0090 & P0087) and and I think the broken pieces may have caused the timing chain to skip a tooth or two causing bent valve(s). However, not sure how to confirm the bent values without pulling the heads which is a pita. I removed the spark plugs and the crank turns smoothly (by hand) a little less than 180 degrees before it binds up in either direction. I also removed the intake manifold to watch the intake values actuate when I rotate the crank and surprisingly I don't see any valve movement on either bank within the 180ish degrees I can rotate the crank. I am not that familiar with the VK56VD engine so curious what I should be seeing in the valve movement and if others have a theory I should check into. Perhaps the oil pump is causing the crank bind? (finger crossed)

I'm having the same issue...have you found a solution yet?