As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) #2 ENGINE BEGAN TO RUN ROUGH AND BACKFIRE IN CLIMB. ENGINE WAS SHUTDOWN AND AIRCRAFT RETURNED TO BASE. POST FLIGHT INSPECTION FOUND THE #6 CYLINDER EXHAUST ROCKER BOX SECTION BROKEN LOOSE FROM THE CYLINDER CAUSING THE EXHAUST VALVE TO REMAIN CLOSED. #6 CYLINDER REPLACED, ENGINE OIL SCREENS INSPECTED, ENGINE GROUND RUN SERVICEABLE AND AIRCRAFT RETURNED TO SERVICE.