I just got my old man's '08 Accent for my own, and it's had a random misfire problem for some time now. The odd thing is, the MIL doesn't always stay lit, even though I haven't replaced any parts yet; sometimes it's on, sometimes it's off, but I know that misfire problem is still there. I know the problem is the coils, I just haven't had the money to do anything about it, even when the car was his. I will soon, though, so that shouldn't be a problem in due time.

Another issue the car has been having is that after long hauls on the freeway when the car gets hot, the transmission doesn't shift smoothly at all after exiting the freeway.

I think the misfires caused by the coils are playing havoc with how the computer sets up shifting patterns, and when I replace the coils the transmission will behave better coming off the freeway, but I'm not 100% sure about that. Anyone else having/had this issue with their Gen3? If I'm wrong about the bad coils messing with shift patterns, what else could it be?

 

I replaced spark plugs and found corrosion on the- coil- on- plugs.
I cleaned them off with electric contact cleaner.

miles later I had a misfire check engine light and took in the same 06 accent AT.
to the mechanic.....they replaced plugs, cleaned throttle body and reset the CEL.
its been fine for some 30k miles