Hyundai Repair: cylinder 3 misfire, secondary ignition, system plugs

Question
My check engine light came on and said cylinder 3 misfire. I have changed the plugs and cords and it was good for 500 miles then it came on again with the same code. What's next?

Answer
Although spark plugs and wires are the most common causes of misfires, anything that will cause a loss of power on one cylinder will cause a misfire.

In this case, since replacing the plugs and wires seems to have changed the issue, we'll start with the hypothesis that the change had something to do with the work that was done.  Most misfire issues are caused by secondary ignition system (plugs, wires, coil) problems, with such problems causing a noticeable lack of power and vibration from the engine.  If you can indeed feel the misfire, then I'd suggest starting with trying to locate whether the coil or wires are arcing.  Often this can be accomplished by spraying the wires/coil with water.  My primary suspicion would be that the coil is arcing or that the wires are of poor quality.

So far, I'm answering in generic terms because I don't have any information identifying your vehicle.  If you follow up with the year and model of your vehicle and which engine it has, I can provide you with more specific testing information.