Percolation? Heat soak? Don't drive during summer??

He said it wasn't grounded. He just stuck the green wire under the ground to get it out of the way. The green wire is likely damaged or rubbing somewhere. Until he figures out where, best to keep it disconnected or removed (I agree removal is overkill, it it's up do doc).

I'll probably just remove the wire from the coil right now to do like you said figure out where the problem is.