its defo not a ground mate as you checked the loom
and it is fixed to the passengers head via a ring terminal on the o/e ecu earth point,
i will check the relays, fuse box and fusebox terminals this week to see if that is all ok, failing that im as lost as every one else.
one thing that is confusing, on the log the spikes is not on going is it, there is a blip where there are 2 large blips possibly a couple small ones then its fine,
i have noticed though, the spikes are bigger if the laptop is plugged into the cars battery as power,