I'm used to wasted spark ignitions. All my bikes have always had them. So have the outboards. Spark fires on both sides, I understand that.
Enter the eternally baffling 1991 Miata, with it's wasted spark ignition. And yes, this is the same Miata that runs rough intermittently below 2000 rpm and insists on flunking emissions.
On each of the two coils, one side fires at twice the rate of the other side. Eh? I've never seen a wasted spark ignition do this, and I don't see how this Miata's coils are doing this. Every wasted spark coil I've seen fires both sides at the exact same rate.
I did also discover that the #4 lead shows a fail to fire that almost perfectly matches the stumble in the engine. Yippee? Not so fast. The #1 lead, on the same coil, does not so perfectly match. In fact it seems to actually do a double fire on the stumble.
I'm inclined to simply replace the coils, and I wish I could just replace the 1-4 coil, as that's the one that seems to be acting up. But you have to buy a whole coil pack assembly, and that costs money. I'd rather study things a bit more before buying a new coil pack, but detailed diagrams of the way Mazda wired the Miata ignition are remarkably lacking.
Any clever observations or thoughts on this ignition oddity?
