When they fail, they get extremely hot and the insides melt out.
All six original coils and 8 new ones from several brands, including OEM have failed this way.
New ones have failed in as few as 3 miles, or as long as 3,000 miles. It is sudden and totally random.
The sparkplugs have been replaced with the correct part and gap to rule them out, coils keep failing.
The only known issue with the car is a supposedly bad diode in the alternator as shown on a test, although this doesn’t seem to cause any problems and charging voltage looks smooth on the oscilloscope.
I am at my wits end with this and have no idea what to do.