SPARK PLUG WIRE ROUTING - MINIMIZE CROSSFIRE. Pontiac LeMans 1983

For 1990-2009 cars

# SPARK PLUG WIRE ROUTING - MINIMIZE CROSSFIRE

#### VEHICLES AFFECTED: ALL 1981-83 VEHICLES EQUIPPED WITH 5.0L V8 ENGINES AND ESC SYSTEMS THE SPARK PLUG WIRE ROUTING ON 1983 5.0L V8 ENGINES HAS BEEN RE- VISED TO MINIMIZE THE POSSIBILITY OF CROSSFIRE BETWEEN CYLINDERS 5 AND 7 ON THE LEFT SIDE AND CYLINDERS 4 AND 8 ON THE RIGHT SIDE. IT IS IMPORTANT THAT THIS NEW ROUTING BE MAINTAINED DURING SERVICE, AND RESTORED TO ORIGINAL CONFIGURATION WHEN WIRES ARE DISCONNECTED OR REPLACED. THE CORRECT OR RECOMMENDED WIRE ROUTINGS ARE SHOWN IN FIGURES 1 THRU 6. CROSSFIRE OCCURS OR HAS THE TENDENCY TO OCCUR IN ALL V8 ENGINES, BUT IS ENHANCED BECAUSE OF THE RELATIVELY HIGH COMPRESSION AND THE ESC SPARK RETARD SYSTEM. CHANGING TO A COLDER HEAT RANGE SPARK PLUG, ALTHOUGH DIRECTIONALLY CORRECT, DOES NOT ALWAYS ELIMINATE THE CONDITION. CROSSFIRE OCCURS USUALLY IN THE FOLLOWING MANNER: WHEN CYLINDER 5 FIRES, A VOLTAGE IS IMPRESSED ACROSS THE ELECTRODES OF THE SPARK PLUG IN CYLINDER. THIS IS DUE TO CAPACITIVE COUPLING BETWEEN SPARK PLUG WIRES. THE STRENGTH OF THIS CAPACITIVE COUPLING DEPENDS ON THE DISTANCE BETWEEN PARALLEL WIRES AND THE LENGTH WHICH THEY ARE ROUTED PARALLEL. WHEN THE ESC SYSTEM IS RETARDING THE SPARK TIMING DUE TO DETONATION, THE VOLTAGE REQUIREMENT INCREASES, THUS INCREASING THE CROSSFIRE POTENTIAL. WHEN CROSSFIRE OCCURS, A CUSTOMER MAY COMMENT ON SUCH THINGS AS: - DETONATION - POOR OR ERRATIC PERFORMANCE - LOSS OF POWER THE FOLLOWING FIGURES SHOW THE RECOMMENDED SPARK PLUG WIRE ROUTING.

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.