Why do the V8 coils fail? A few thoughts...

[Robot]

It's usually the plug boot that starts leaking voltage and creates a misfire. In my experience is that most misfires can be repaired long term by changing all the the boots and spark plugs as a set. The boots are made by AC and cost about $6/ea. My '03 LS8 has 210,000 miles, and I haven't bought a coil in the last 110,000 miles, but I have changed all the the boots and spark plugs 3 times in the last 110,000 miles.

There's history of PCM's failing fairly often on LS. I'm sure this is related to misfires. Deal with them as soon as possible!

I don't know about everyone else but, I stretch my springs so they stick out of the boot about a 1/4 inch because I've always felt they were barely making contact with the plug and maybe arcing at that point. Doing that also makes the spring narrower which would likely reduce the chances of it arcing through the boot.