Car was missing and I was through this less than a year ago. Checked all the coils and the one I replaced 9 months ago had a secondary reading of 8.30. I replaced it and all is good now.

Would there be anything particular that would cause the same coil to fail so soon other than a defective coil?

Your coil failure issue can be cause by one or two problems, or the combination of both. PLUGS and WIRES. Use ONLY AC Delco recommended plugs....nothing fancy here like Bosch Platnums, and either AC Delco Wires or Autolite PROFESSIONAL series wires.

I had the same issue using good wires like I mentioned above along with Platnum Plugs. The Platnum plugs (and poor wires as well) have a higher resistance and create more heat in the coils because of the higher resistive load. It will cause the coils to prematurely fail.....most likely with little cracks you can not see (on the bottom); or total failure. In the event of the hairline cracks, moisture will creep in and cause a cylinder(*) to miss fire on a rainy day. Then they will dry out and work fine until they get wet again.

Oh yes, the third problem. AGE. They will fail over time. Just using wrong plugs and wires will make them go sooner.

Hope this helps.

93 SSEi

The same coil for cyl 1 and 3 has now failed twice. I was chasing down a slightly rough idle and i couldn't figure it out. Since I replaced the coil a few days ago the car runs smooth now. I'm thinking I might have just gotten a bad coil from the get go.

Do you have AC Delco Plugs?

When I purchased this 93 SSEi (118K Miles) for my son we did a total tune up including new wires and Bosch Platinum’*. It always had a little roughness to it. Then the coils started going out, only 1 cylinder per coil, but two different coils. Then later, the third coil went bad. After changing coils again, I chatted with the local GM mechanic. He was pretty arrogant, but right.......as he said the 3.8L GMs do not like the higher resistive Platinum’* and will not run as good (he actually called them JUNK, but good for imports) . We changed them out for $1.25 AC Delco plugs....then runs like a dream. No roughness at all....smooooooth, and knock on wood, no more coil issues with a 140K now. SSEi getting 25 mpg @70 on the road.

Regards,

I have Bosch platinum plugs and wires. I believe I should be ok as the problem is with the supercharged engines, which mine isn't. Don't flame me over Bosch as I found out after the fact that these plugs are lousy! All is good right now!!