Ignition Coil Testing

I only have a couple hours in this project. I put some automatic features in the settings. The total period between ignition events is = dwell time + minimum spark duration + off time. The reciprocal of the period, times 15 is the engine RPM (for a V8). At low RPM there is plenty of time for dwell, and spark duration. As RPM increases the available time is less, so dwell must decrease, or there would not be time for a spark. At 6000 RPM, there is only 2.5mS time between ignition firings. The spark duration is reduced, and the coil holds the energy, and the next dwell adds to it. That is what is happening, in the stair step look of the last scope picture. The test counts was set to 8 ignition events, an actual running engine would be stable, like that after the 5th event.

The blue text in the dwell setting is automatically reduced by the program, showing the dwell is reduced to accommodate increased RPM. Same happens if min spark duration is changed.

There is much more that can be done, things like the tester measuring the coil inductance from the rate of current rise, coil resistance and supply voltage.