Hi all, I just joined and this is my first thread so forgive me if there's already a thread about this.
2017 Hyundai Elantra LE with almost 5000 km.
I started it this morning after a night of high wind and rain and it had a very rough idle like a miss, I had a friend do a code check and he got p0303 cylinder 3 missfire . As I said, it rained heavy on Times last night with high winds, so I'm thinking that water may have gotten into a connection somewhere. I know that other things can cause this but because of the rain and wind I'm leaning toward a wet conection, does anyone have any ideas what I could look for. Yes the car does have full warranty coverage, but, the dealer is over 100 km away and if it's just a wet connection, that's something I could correct myself.
Oh, the rough idle only lasted for about 2 - 3 minutes til the engine warmed, then it ran perfectly, that's another reason I'm thinking water.
Anyway, any suggestions would be appreciated.

 

Drive the car for a while and let it heat up
Let sit over night and test drive the next day
See if it gets any better

 

the car ran fine about a minute or two after I started it and has ran fine ever since. Like I said in OP, we had real heavy wind and rain the night before this happened and I think a little water got into one of the electric connections leading to #3 cyl and when the the engine heated up it evaporated the moisture. I also think a little dielectric grease on the right connection will stop this from happening again. That's why I posted, I was hoping someone would have a good idea which conections to start with.
I should have been more clear with my first post.
Thankyou for your post, all advice is greatly appreciated.