Has anyone ever narrowed down a P0300/0301/0302/0303/0304 to a bad coil pack, replaced the coil pack, and has the issue return a few months later?

Here's the story; I'll try and be brief. Original Thread

Last January I replaced all 4 OEM coil packs with the 04-05 packs. Afterwards, just because, I had my injectors tested and cleaned. All were fine. 1 was fair, once cleaned was great. All spray patterns were solid too. Fast forward till now...

Yesterday the car, upon start up, was doing the same thing again. I had time this afternoon to check it out and sure enough same problem. Misfire in Cyl3.

• unplug injector wire on cyl3 (no change in idle)
• unplug injector wire on all other cyls (car stumbles badly)
• apply screwdriver to injector to listen for firing (can hear it firing)
• swap pack 3 with pack 2.
• unplug wire on cyl3 (car stumbles badly)
• unplug wire on cyl2 (no change in idle)
• Move coil packs back to original locations

I had 2 working OEM coil packs left over from the original PITA last year. I figured it wouldn't hurt to test one of the known working ones out. Sure enough, it fixed it.

And now for my question(s):

1. Is there anything that would cause a false positive P0300 error which would be momentarily solved by replacing a coil pack?
2. Is there any systemic problem that is causing my packs to fail?
   • electrical?
   • the pack having to offset something else? (valve adjustment, etc)

Small disclaimer: the 04-05 packs were purchased from ebay (solid seller rep). I have seen people using (or suggesting) the DENSO coils in a recent thread, but I'm a bit gun shy now.

Thanks,
Matt

 

What brand coils ?, made in Japan, China, elsewhere ?.

If you are talking about $20-$30 coils made in China, then yes that is entirely possible to have them fail quickly. When I was recently searching for new coils I read reviews of people getting bad coils on the cheaper ones you find from certain on-line sellers. You can find coils as low as $20 on-line, the better ones will cost more.

 

I feel like this is conclusive of a coil pack issue from your troubleshooting steps. I'm with you that I think it was probably some bad luck on buying a used one. While he is a reputable seller, he may have even done due-diligence and verified that the coil was good, maybe even pulled it from a well-running motor... but when you installed it it was obviously working correctly. He has no idea when the pack will fail, but it may have had some significant miles on it and it was just bad luck that a little while later it failed again.

Buy a used one with x mileage on it. If you're in the 80k+ range you're just gambling.

I would just buy new though. In that thread I think you could buy (4) for as low as $180?