With a little time on my hands yesterday I had a Renault Megane Scenic come in with the usual pencil coil failure. I quickly identified the cylinder by disconnecting the injectors one by one. Cylinder 1 (pulley end) was the culprit & I made the following captures on all cylinders.

This first image shows each cylinder igntion primaries versus current as the vehicle was presented to me. they are set out in cylinder order 1 & 2 Top row & 3 & 4 bottom row.......




This next one shows the result of replacing just the single faulty coil.......




Interesting how the grounding on cylinder 2 (red signal top image) is held totally to ground & the sparkline voltage is noticeably higher in that example. The lower image shows a grounding just the same as all the other cylinders & the sparkline voltage is lower??? I don't know why they aren't held to ground fully, but I have noticed the same thing on other cars too with apparently no ill effects.

The primary trace (in red) on misfiring cylinder appears to be normal with a good sparkline voltage & burn time, even though it had a total misfire. I suppose I must be seeing the event on opposing good cylinder. I haven't studied a wiring diagram yet to see if they share the same grounding trigger path.

Any thoughts anyone?

Cheers