My 2014 Hyundai Elantra sometimes does not want to start. The Battery was checked, it's good. When this first happened black smoke came out of the tail pipe for a while and the engine made terrible sounds. I turned it off and started again, same engine sound. Then turned if off did it again and it ran fine. A week later turned the car on and it was running. I went to touch the heat to turn it on and the car died. Started it again it ran for a few and then died. Started again and it worked. I took it to the station and they didn't get any codes except "Ignition" code. They said could be the battery and it wasn't. Told me to take it to the Dealer since it is still under Warranty. The dealer never has time to look at the car. Yesterday tried three times to start the car and after the third time it finally came on. The Mark went up to 5 and then back down to 1 and hasn't gone to 5 since. Any ideas?