I replaced two coil packs on my car, and not even a week after replacing them I get a misfire, turns out the old two are duds, waiting on new ones from Honda to get here. While I wait, I'm curious as to why whenever you replace one or two coil packs with new ones the old ones die so quickly. This isn't just on my car, I've observed this countless times. Anyone got any ideas?

I'm guessing that it's because the resistance of the old coil packs is greater than the new ones, and this difference is resistance causes a change in voltage, so the computer sees this voltage spike and says, "uh wtf is going on how am I supposed to give consistent voltage to these coils when I get a different resistance value each time, oh well I'll try anyway but what do I know I'm just a dumb computer."

 

I think you are overthinking it, the S2000 ecu isn't that intelligent. Basically the parts are made to very exacting specs and tolerances, the 4 coils in your car are operating in exactly the same conditions, so the chance of them failing around the same time is pretty high. When you get 1-2 coils failing first, you might as well replace them as a set and keep any good ones as emergency spares.