ENG. MISFIRE DTC P0305,P0306, (S/P BOOT REPL. PLUG & WIRE. Buick Century 1998

THIS IS A MONTHLY SERVICE NEWSLETTER ARTICLE THIS INFORMATION IS NOT INTENDED TO BE A PUBLISHED BULLETIN

CONDITION:

SOME OWNERS MAY COMMENT ABOUT A ROUGH RUNNING ENGINE AND THE MIL IS ILLUMINATED. THE TECH II INDICATES A P0300 OR INDIVIDUAL CYLINDER MISFIRE CODE (P0301, P0302, P0303, P0304, P0305, OR P0306). TECHNICIAN FURTHER DETERMINES THAT THE SUSPECT CYLINDER HAS A SPLIT BOOT ON THE SPARK PLUG WIRE AT THE SPARK PLUG.

CAUSE:

THE GREASE INSIDE THE SPARK PLUG BOOT MAY DETERIORATE THE RUBBER CAUSING THE BOOT TO SPLIT AND EVENTUALLY MISDIRECT THE SPARK TO GROUND.

NOTE: THE CONDITION IS MOST PREVALENT ON CYLINDERS 1,3,5. THE CYLINDRICAL HEAT SHIELDS ON THE PLUG BOOTS FOR CYLINDERS 1,3,5 IS UNIQUE TO THE W CAR. CYLINDERS 2,4,6 ON THE W CAR ALSO HAVE THE SAME SHIELDS AS DO OTHER PLATFORMS (C, H, OR G), HOWEVER, THE DETERIORATION HAS NOT BEEN FOUND ON THESE CYLINDERS. APPARENTLY THE SPARK PLUG BOOTS ON CYLINDERS 1,3,5 ON THE W CAR MAY BE SUBJECTED TO HIGHER TEMPERATURES, HUMIDITY AND OTHER ENVIRONMENTAL INFLUENCES THAT ARE AGGRAVATING THE CONDITION.

CORRECTION:

PACKARD, SUPPLIER OF PLUG WIRES, IS CURRENTLY TESTING NEW GREASE THAT WILL NOT DETERIORATE THE RUBBER BOOT. UNTIL THE NEW GREASE IS MADE AVAILABLE, THE FOLLOWING REPAIR PROCEDURE IS SUGGESTED:

1. INSPECT ALL SPARK PLUG BOOTS FOR SPLITTING AT THE PLUG END BY REMOVING THE WIRE FROM THE PLUG AND THEN REMOVING THE CYLINDRICAL HEAT SHIELD FROM THE BOOT. PINCH THE RUBBER BOOT WITH YOUR FINGERS AND VISUALLY INSPECT FOR CRACKS.

2. IF A CRACK IS FOUND, REPLACE THE WIRE WITH A NEW WIRE, HOWEVER, FIRST REMOVE AS MUCH GREASE AS POSSIBLE FROM INSIDE THE BOOT OF THE NEW WIRE BEFORE INSTALLING THE HEAT SHIELD AND PUSHING THE WIRE ON TO THE SPARK PLUG. ALSO REPLACE THE SPARK PLUG ON THE CYLINDER WITH THE SPLIT BOOT.

3. IF A CRACK IS NOT FOUND, THEN REMOVE AS MUCH GREASE AS POSSIBLE FROM INSIDE THE BOOT AND SIMPLY REINSTALL THE HEAT SHIELD AND PUSH THE WIRE BACK OVER THE SPARK PLUG. DO NOT REPLACE THE SPARK PLUG.

FIGURES: 0

GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS, NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR TO PROVIDE INFORMATION THAT COULD ASSIST IN THE PROPER SERVICE OF A VEHICLE. PROPERLY TRAINED TECHNICIANS HAVE THE EQUIPMENT, TOOLS, SAFETY INSTRUCTIONS AND KNOW-HOW TO DO A JOB PROPERLY AND SAFELY. IF A CONDITION IS DESCRIBED, DO NOT ASSUME THAT THE BULLETIN APPLIES TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE THAT CONDITION. SEE A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.