I meant to submit a picture, but if you’ve seen one ignition coil, you’ve seen them all.
Okay that’s absolutely not true. Not true at all…
First one I bought, from a “guaranteed fit” website, did not, in fact, fit. My car has a 4-pin connector for the coils. This one had only three. So back it went. Went to the dealership and got the correct coil, which is what I should have done in the first place. Serves me right for trying to save a couple bucks…
Swapped it out and goddamn it’s like having a whole new engine! I had no idea one sickly coil could make that much difference in an engine’s performance. This thing much have been bad long before it started throwing codes.
The old one looks fine on the outside. I’d imagine whatever’s bad is somewhere inside the epoxy, which I’m not going to bother digging through to find. Cleared the engine code and I’m gonna hold on to the old one just in case.
First time doing this too. Had no idea it was that easy. I’m not really a car guy.
If you still have the old coil pack, clean it up really well and then look it over carefully, you’ll probably see where it failed. There will probably be one or more visible micro cracks going down the side of it.
That’s the typical thing that ends up killing them, long term heat stress causing micro cracks, which gives the electric spark a gap to escape somewhere else besides the spark plug wire, or just causes it to fail open circuit, but either way causing no spark at the spark plug itself.
No, cleaning it up will not fix the old coil pack, but is often informative for curious minds that would like to see where and how it probably failed.
I do still have the old pack, and I did clean it off real good and look it over. Didn’t really see anything in the way of cracks, shone a light down into the boot and the contact didn’t look corroded or dirty. I guess I can look it over again but I just assumed the damage was internal and I can’t see it.
Now that is entirely possible too. Not as common, but still possible. In my experience, the cracks are almost always around the manufacturing seams, when they’re visible anyways.
Some mysteries aren’t always visible, but either way, glad you got it sorted out and fixed 👍
Generally what I’ve read is the epoxy tends to break down and allow high voltage shorts internally. Nothing to really see and very difficult to test. They usually pass standard continuity and resistance tests.
I’ve had a handful of individual coil-on-plugs fail, couldn’t see anything. I had a failed 4-port coil pack that had a hidden crack found by seeing spark discharge outside the plug