I need answers!

I have a 2007 Hyundai Elantra. What would cause a misfire in cylinder #4???

Many things! Are you sure you’re not covered by the two year/24,000 mile emission warranty from the manufacturer?


i’m not sure if i am or not. what would be some of the things that could cause it? When i took it to the dealer, they said it was the spark plugs?

I think the Elantra has a 30K spark plug change interval. Where are you in terms of miles?

Elantras have a 10-year, 100,000 mile powertrain warranty. Take it to the dealer.

about 31,000. I bought it used and it’s an 07. The guy I bought it from told us it was fully inspected before we bought it, but maybe not as fully as he thought…

That powertrain warranty only applies to the original purchaser. Subsequent owners only get the remainder of the 3 year/36K mile bumper-to-bumper warranty. So the OP may still be covered here.

That’s right. Change the plugs.

There are other things that could cause a miss on cylinder 4 also. Bad injector, coil, etc. Spark plugs are not going to be warrantable after 24k miles and they’re considered a maintenance item.

I realize the car only has 31k miles on it but you bought it used and if the car were mine, and since the plugs need to come out as a first step, a compression test should be run.

Who knows if a prior owner may or may not have overheated it and caused a loss of compression. If a mechanical fault exists due to fried piston rings, iffy head gasket, etc., then one could throw parts at it forever and solve nothing.

I say pull the plugs, run a compression test, and make absolutely certain that the engine does not have a serious problem before going very far with this.

Did you buy this from a dealer or an individual? If a dealer picked up a problem car at auction they may have sold it to you not knowing there is a problem. If an individual sold you a problem car then you can pretty well figure they knew about it.