Rough cold engine start-up..
My 2003 Altima has this rough engine start. It only happens only during a cold start. I cannot decribe the sound but I would compare to a rattle/high-rev sound. It only lasts for 1-2 seconds around 1500-2000rpm. As soon as it hits low rpm idle it sounds perfectly fine. All my fluids are normal, no mechanical problem, and no check engine light. I dont know what it is?? Someone please diagnose....
1st start of engine the sound would occur, after warm-up and driving normally, the sound does not occur during normal engine turn-off and start-up in between destinations. I would drive 80-100 miles in day and it occurs ONLY during first cold start-up, if I would be at a location where the car has fully cooled down the sound would happen again since it would be considered a cold-start. I dont know what the issue is... Please elaborate.