What might be causing coil packs to go bad?

[swynx]

Took the engine out for a rebuild. First try it started right up, shut it off and couldn’t get it to start. Confirmed fuel, then switched out the coil pack for a confirmed working used one.

then I got one start, shut it off and it wouldn’t start. Checked the ohms on both coil packs. The secondary’s all check out fine around 13. But the primary’s on both coil packs are measuring 2+ and should be .3-.7

im not sure what that really means. But I’m assuming it has something to do with my no start.

 

[bobbywalter]

Heat. Lack of beer...but mostly heat and water and vibration.

 

[ericbphoto]

Heat has been killing electrical coils of all types for many, many years, since the last century, in fact. Heat is generally bad for electrical and electronical stuff.

If a new coil died, probably manufacturing defect which caused the coil to overheat itself.

 

[RonD]

Actually the coil "packs" can show .9-1.8 ohms

The .5-.9 was for individual coils, and some newer ones are 1.5ohms

2 ohms does read a bit high but if all 3 coils showed that(assuming V6 coil pack) then I wouldn't think they were the problem, more probable is, the OHM meter was reading high

Unless there was a big crack across the coil pack only 1 coil in the pack would be usual failure mode, not 2 and especially not all 3

Yes, heat kills ignition coils, which is why they crack, under 2ohms is literally an electric HEATER coil and I don't even think they run that low of resistance, lol
So if a computers ground transistor should fail and keep coil grounded or coil's ground wire was chaffed and grounding out it would over heat pretty quickly, but just that one coil in the pack, if it was center coil then "maybe" it could effect the 2 outer coils, but big maybe