Havent started it up again to test unplugging the front bank 1 o2 and will do that on next startup. I confirmed the battery is healthy at the local OReillys.
Did a leak down test, for what it might be worth, though now feeling it was not helpful (yet). Misfire is too bad to get the engine warm and cylinder 3 (misfiring cylinder) had low dry compression and fine wet compression #s (95psi dry, ~155psi with a drop of oil added) and all other cylinders were within acceptable range each other, around the 150 mark
Loosened crankcase cap and coolant cap, intake piping removed down to TB.
Did a leak down test on cylinder 3 (multiple tests) and was getting a 90% loss of compression (100psi down to 10psi). I could hear air escaping out of the cylinder at a rapid rate but couldn’t identify any leaks in the engine bay: coolant tank was still, no air bubbles or hissing, no hissing from crankcase cap, no hissing or air noticed from TB, couldn’t identify any air leaks in the valve cover or injectors or anything of the sort. I did hear air coming out of the exhaust, indicating an exhaust valve issue I guess.
I wasn’t quite satisfied (still not) with the diagnosis so I tested cylinder 2 as it came up close after cylinder 3 in the firing order (…3-7-2…) and got the same diagnosis, bad exhaust valves or air only escaping or heard from the tailpipe and also reading at 10psi when it should be close to 100psi (if healthy).
I had limited time with the air compressor so will get another and do more testing.
In the meantime, does it sound like I’m messing up somewhere or should do something else when I re-check? Would like to get it figured out ahead of time. A couple of videos of the leak down test and pictures of cylinder 3 intake valves from when I was doing the oil check valves.