2011 Elantra Touring Sport Engine code p0303
 

I have got codes P0303 and it tells me misfire on No 3 . I switched spark plugs and no improvement. I then exchanged the 2 coils 2 & 3 to 4 & 1 and still the same. What can I do now. Any help would be greatly appreciated …. Thanks Roger B

Since we don't know if the cause is mechanical or electrical , a compression test would help hopefully eliminate one or the other and then we go from there.