I noticed a foul smell coming through my AC one day when it was on the outside air setting. I took it to a mechanic and they said there was a huge crack in my engine block which causes my car to leak SIGNIFICANTLY, like a quart and a half of oil between oil changes at 3000 miles. The oil drops onto the hot engine and burns creating this horrible smell and smoke coming up from my hood. I hear this is a pretty common problem with this make and model of accord.