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I have a 2015 Buick Encore with a Ecoboost engine that has numerous coil packs replaced in the the last year(about 4). The issue is normally a miss in cylinder 1. Not sure how to approach troubleshooting this issue, I suspect that to much voltage is getting to the coil, but not sure how to verify this and why would it affect cylinder 1 all the time.
I'd suggest starting with monitoring voltage on the #1 coil power and ground with the engine idling. You'll need a multimeter and a backprobe do to this test. Compare your readings to the other coils. Coil powers should be within .5V of B+. Coil grounds should be less than 300mV.
If there's no power or ground issue, consider the spark plugs themselves. Are they the correct plug with the correct gap? If in doubt, go OE/OEM. Boosted engines tend to put additional stress on the ignition system, and can be very particular about spark plugs.
The coils are causing a miss on cylinder 1. I started by switching plugs, then checked the compression. I have changed plugs twice, but will pull them again and verify they are the right kind and gap.
The coils are all molded together, but maybe I can find a wiring diagram to help show me what wires are what.
It takes a few months for the coils to start failing.
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