Got an 08 F-350, it has 110,000 on it. Put a K&N cold air on it plus 5" dpf back. Lately it cleans the exhaust filter everytime I drive it. Sometimes it will smoke for less then 30 seconds and it smells awful, not oil smoke or anything like that. It also would make the turbos sound like your coming off the gas hard under heavy boost. I drove it for an hour the other day on the way to my dealer, it cleared up after 20 min. He reflashed it for a mileage tune and computer updates, that was 5 days ago and now its back to the same stuff. I changed back over to the stock air box and all it did was lose fuel mileage. Maybe a bad dpf I have heard. The truck had blown a motor and split the head gasket at 30,000, not sure if a new dpf/cat was put on. Any ideas?
Thanks, tried to make that as short as I could