CUSTOMER CONCERN The engine misfires and stores DTC P0300, with the misfire isolated to one cylinder. CAUSE Swapping the spark plug and wire moved the misfire to another cylinder, confirming failed ignition secondary components. CORRECTION Remove and replace the spark plugs and spark-plug wires, clear DTC P0300, and verify the misfire is eliminated.

CUSTOMER CONCERN The engine runs very poorly after air-filter service, pings under load, remains in open loop, and stores lean and misfire DTCs. CAUSE Inspection confirmed debris contamination on the mass-airflow sensor element, causing incorrect airflow measurement and the lean misfire. CORRECTION Clean the mass-airflow sensor element and air-filter housing, clear the DTCs, and verify closed-loop operation and normal engine performance.

CUSTOMER CONCERN The engine runs rough with a timing-chain rattle and stores DTCs P0011 and P0300. CAUSE Diagnosis confirmed a worn timing chain as the source of the camshaft-timing fault, misfire, and rattle. CORRECTION Remove and replace the timing chain, clear DTCs, and verify smooth engine operation without timing-chain noise.

CUSTOMER CONCERN Customer states the check-engine light is on with misfire codes even though the engine runs smoothly and no misfire is felt. CAUSE Diagnosis confirmed the PCM calibration was falsely detecting cylinder misfires. CORRECTION Program PCM with updated calibration. Clear misfire DTCs and perform crankshaft-position relearn.

CUSTOMER CONCERN Multiple-cylinder misfire codes were recorded even though the engine ran smoothly and no actual misfire was felt. CAUSE The PCM calibration was falsely detecting misfires. CORRECTION The PCM was reprogrammed and the crankshaft-position sensor learn procedure was performed.