I illuminated each coil from being a problem this way. Genuine Spark analysis. With motor running, coil out, plugged in with a good spark plug and grounded. Watched each coil pattern as it generated spark. I had a solid pattern on all without fluctuation. This test provides Primary and Secondary tests @ the same time. Does anyone have a different opinion ?

Thanks

 

It's easy to jump a spark across open air.

Try it in the combustion chamber (which can reach several hundred degrees F), igniting a fairly precise air/fuel mixture with 150+ lbs of compression in that same space in an engine tasked to move 5000 lbs of truck. Ain't so easy anymore.

Just because the spark looks good at idle doesn't mean that it'll do good under load. The most accurate way I know of testing an ignition coil is with a coil stress test, but this requires Ford's WDS scan tool setup. Snap-on makes add on adapters for use with their Vantage and MODIS graphing meters and labscopes to test ignition coils, but I dunno how accurate they are. Just as an ignition coil can test okay resistance wise, that doesn't mean that it won't flake out under load.

 

Thanks, that's what I wanted to know. Wether I could subtract that from an ongoing problem or keep it as a possibility.