Hi guys, I might be a bit vague on details here but I can post them tomorrow if you feel it necessary!?!

So the mrs rings me at 4pm today because a light has come on the dash, P0300 & P0302. Due to the time i bviously havent had chance to have a good look at it yet but im after a bit of theory help if poss because google is confusing me. Plugs look good, and injectors scope ok, live data appears ok but we've got misfire counts on every cylinder, particularly cyl3!! Codes clear but soon return when running!

This is fitted with 3-wire cop's; now my understanding is that we have a nbv feed, a ground and a 5v pulse from ECU?!? Bear in mind that the batt voltage is 14v I have a 12.7v feed, good ground and a 4.3v pulse; unplugged there is nothing down any wire? Primary currant reaches 9.8amps across all three cylinders and I swapped coils round to see if the p302 moves and it does not! This is as far as I've got, now my suspicion is a bad CPU earth? However, as I have very little experience with these 3 wire beasties I thought I'd do a bit of googling and see what the deal is, my confusion comes because on example waveforms posted online they all show a pulse of different voltages, some are 5v, some are 4?, there are even some at 3????

Could anybody please inform me or point me in the direction of a pdf, video or web page etc where I can see what Im meant to be looking at please?

Ps a wiring diagram would be useful too if anybody has one? Reg is B3 EVW I can post VIN tomoz if necessary?

Thanks
Craig