im just trying to rule out as much electric noise as poss
Get pic of mine some 2morow if the weather good,
think mines r connceted to: alternator, coil pack, ecu earth (under windscreen panel...
are i see
Inlet manifold makes sense, I would guess that the gasket is designed to be airtight rather than electrically conductive. The alternator is mounted on a couple of adjustable bolts, again not that great for electricity.
I can imagine the coil packs being a biggy, unfortunately in my particular car I don't remember there being a common ground for the coil packs.
I can't see one for the chassis itself? I'd have expected one somewhere going to the bodywork?
Just to up my earthing points
ecu earth ( under windscreen panel.)
Rocker cover - coil pack ground,
Alternator
Inlet manifold
where about is the ecu earth is it right at the back?