Follow up on my original post: looked like a mouse had eaten my sub wire from the main harness to the knock sensor completely through. The sub wire had to be purchased from
Honda for about $15, the knock sensor I got from an auto parts store for $20.
I spent about 3 hours taking everything apart, and 2 hours getting it all back together. On the tear down, probably half the time was spent trying to figure out if I could get to the knock sensor without removing more and more stuff. I ended up having to remove the intake manifold, injectors and fuel rails, and even the power steering pump to get to one bolt on the lower intake manifold.
Attached is a pic of the knock sensor and it’s location in the valley. Note the subwire is not connected in this picture.
The J35 has such a nice open and warm spot under the intake plenum for mice to build their nests. Spent a good deal of time with a flexible grabber pulling hood/firewall insulation out from under the plenum on my brother-in-law's Odyssey when we replaced the timing belt.