the larger wire coming off the front right side of my valve cover(groundwire?) is disconnected due to fraying. what does this affect? what is it for? just a ground? has been disconnected as long as i have had this car.
I don’t think Honda would have put it there for no reason 
Mine was removed for a long time too. I replaced it with some extra 8ga wire I had.
My bolt is stripped, so I just wired a couple to the other side of my valve cover, near the cam seal. It never hurts to have more ground wires.
mine was also frayed so i put some 8 guage in there and called it a day. not only was that ground pretty shotty, but my battery ground and block-chassis ground where also in pretty bad shape.
I think because it is on the valve cover it is to make sure that the cover is grounded, as the cover may not get a good ground to the head, because of the gasket/gasket seal, and has more to do with shielding the radio from spark plug interference, [RF] then anything to do with grounding to motor and alt. to the batt. and chassis, as removing it seems to make no diff. at all. I have checked, [with a DVM] if there is a diff ground potential on the motor with and without that ground, and there is not, I have however fixed noise problems on the AM radio by repairing that ground. 
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