I know this is an old thread, but since I came to a successful resolution of the "knock" issue I figured it may help some one in the future. (That's why I'm wasting server space putting it up. If the mods feel it's a waste of space just file this post in the circular file.
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Okay, so there is no way around the conclusion that the cause of the knock was me, or my inattention to detail. The knock came about because the spark plugs were loose....not finger tight loose, but loose enough so that one light application of force with the 3/8" ratchet and spin them out by hand loose. This conclusion is hindsight as some one from the brain trust we have here may have a better explanation. I put new plugs in and I have no "knock" any longer. To me the simple answer is as I said....I should pay attention better & don't let the plugs get loose!
The last plug change I did was two yrs ago. I use 41-602's with a light coat of motor oil on them as that's what was there from the factory. No anti-seize was on the FR2LS plugs that were in my car when I got the car. I never got around to doing a plug change this season so I never even checked the plugs for tightness and I do use a T/Q wrench when I change plugs. It's a beam/pointer type so okay I'm going to buy a new digital one some day. But I can't blame the wrench for my slackness!
Jut a fwiw, got some knock & no codes & good fuel PSI & no other stuff going wrong, check that the plugs are tight! Don't be like me & forget about them!
Tom