THIS PRELIMINARY INFORMATION COMMUNICATION ADVISES THE TECHNICIAN THE STEPS TO DIAGNOSES AND REPAIR VEHICLES WITH AN ENGINE THAT RUNS ROUGH WITH A KNOCK NOISE AND OR BACKFIRE SOUND COMING FROM THE AIR FILTER. SOME VEHICLE MAY HAVE A SERVICE ENGINE SOON LAMP WITH DIAGNOSTIC TROUBLE CODES P0300-P0308 OR P0263, P0266, P0269, P0272, P0275, P0278, P0281, AND P0284. THE CAUSE OF THE CONCERN MAY BE THE RESULT OF A LACK OF LUBRICATION TO THE ROCKER ARMS AND VALVE TRAIN COMPONENTS. THE CAUSE OF THE LACK OF LUBRICATION MAY BE OIL FEED HOLES THROUGH THE HEAD GASKET(S) THAT ARE NOT COMPLETELY PUNCHED THROUGH. ONE OR BOTH HEAD GASKETS WILL NEED TO BE REPLACED.
