What would cause a misfire in a cylinder of a 2001 Ford F-350?

Answer 1

(Answering as if it's a 7.3L diesel) Their are many contributing factors for a misfire or rough idle. I've found the most common issue with the 7.3L is typically electrical connector issues or just internal failure of the injector due to lack of maintence of the fuel and oil systems. Other ways is low compression cause by valve seat issues, compression ring issues, cracked pistons, bent valves, low fuel pressure, low pressure in the high pressure oiling system. But like i said the main problems is typically under valve cover harnesses coming apart causing an open between the pcm and injector coil which causes the injector to not fire. These engines use high pressure oil to fire the fuel into the combustion chamber. High pressure oil is pressurized to about 3300psi (max) which then is delivered to each head's oil rails. The oil then enters the injectors threw the ports in the head. The oil waits for the coil to energize and open allowing the high pressure oil to flow into the plundger chamber pushing down on it which opens another chamber lower in the injector where the fuel (at 55-65psi) is waiting to be injected into the cyl. This is said because if you don't keep up on your oil changes the dirty oil can leave sludge behind in the small cavities of the injector causing it the not operate correctly and causes a misfire. Same goes for the fuel as well. So yes not changing your oil in this engine can cause misfire issues if neglected long enough. Hope this helps. Change your oil!