I have a 2018 Sonata that has started to have a rough idle at times when in drive, stopped and with no HVAC on. I had to dealer, they stated there was a misfire and changed one plug and coil. This is still happening. Thoughts?

  • Dirty fuel injectors, spark plugs, plug wires, distributor, idle control valve, or air/fuel ratio isn't adequate meaning it could be the MAP/MAF, fuel regulator, fuel pump or PCV value, but that's very last, it could also be a small Crack in a vacuum line, a bad egr value also causes a rough idle
    – user38183
    Nov 27, 2018 at 0:17

1 Answer 1


I know for the 2018 Elantras there's a big misfire thing going on it has something to do with the ecm creating a bad misfire the only thing that is suggested that I heard that works is to replace the plugs and to replace the coils with green dots on the top. Hyundai is still waiting for the update to be released from the engineers

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