Me to at 12000 klm, you could hear it sucking in the air through the airbox and the revs rising and dropping for 1 minute on startup. Took it to the dealer to check it out but they couldn't fault it. After a month of it getting worse with backfiring through the airbox and popping out the exhaust I went back and left it over night to replicate a cold start. Turned up next morning for them to start it up and the car done its coughing and farting for the 1 minute start. Service manager asked to leave it for the day to make phone calls. Picked it up in the afternoon and was told they had done a software upgrade, I asked how he went making his calls to Hyundai and his reply was that the national service manager said it was unique to my car. Alas problem not solved, then went back to the dealership, who have been great in regards to it, left with them for a week hooking up to the flight data recorder which was showing it to running rich on the start. Long story short they changed coil packs with a car on the lot, didn't work, then took out the injectors with 3 of them nearly blocked up with carbon buildup. Injectors replaced. Organised to pickup the car at 8.30 in the morning to inspect cold start up with the service manager, who had a new nline as a comparison. Before we started the he went on to tell me that it is the fuel quality that we use here blah blah blah. Anyhow started mine and it did start a lot better, no fluctuating revs and popping through the exhaust. Then he started the new one with a sold sign on the windscreen for comparison and lo and behold it ran like a dog, I said to the service manager so much for his fuel theory and that the new owner of the car isn't going to be happy. Now at 24000 on the car now and starting to do it again, my theory is that with direct injection it is getting carbon build up and maybe Hyundai should start fitting oil catch cans to maybe rectify this problem
