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.
I had no idea one sickly coil could make that much difference in an engine’s performance.
It really is wild how sensitive cars can be, but it makes complete sense when you think about it. Car go vroom when air and fuel go boom inside motor, but only when it go boom when you want it to. If your car is a 4-banger (4 cylinders, just a guess), having a single faulty ignition coil pack means that a quarter of your engine isn’t going boom the right way.
Time for me to plug my dull man story:
I just fixed my new-to-me 07 Honda Fit last week.
The nut circled in red is a set nut, keeping the flat-head bolt it’s attached to in place. Adjusting the bolt adjusts the gap between the rocker (the arm things on the shaft that you can see) and the valves they open and close (the spring loaded things underneath). My car was stalling while idling (would even die while shifting gears sometimes). Adjusting those bolts to be within spec took the car from a rough idle at ~600RPM and dying any chance it got, to a rock solid 900RPM idle with no signs of giving up before putting another 200k miles on.
If you mess up a car’s air, fuel, and sparky mixture, they generally will tell you they do not appreciate it.
If it’s a dual fire coil design, then a 4 cylinder only has 2 coil packs, each pack delivering spark to 2 cylinders simultaneously. So on those, if one coil pack goes completely bad, then you haven’t lost 1 cylinder, you’ve lost 2 cylinders!
Yeah, that’s happened to me before, half the fucking engine went dead, and I just barely could make it home, while my passengers couldn’t have cared less and just wanted me to drive them around, probably to go get some weed.
I had to tell them to fuckoff, either get out of my car, or you’re riding back home with me while the car still half runs, cuz the next destination is to park it at my place until I can get it fixed.
Those dual fire systems are … interesting … to say the least …
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
How did you know it needed replacing?
Engine threw a code for a cylinder 2 misfire, which I also felt as I was driving. Now like I said I’m not a car guy - I just kinda learn as I go - so I did some reading up and talked to some friends who actually are car people, and determined that a bad ignition coil was the likely culprit.
I’d like to add that I have my own OBD2 reader and highly recommend that everyone who owns a car have one too. They’re cheap and it pays for itself the first time you use it to diagnose your own car problem.
Same. Those readers are SUPER handy.
