ENGINE MISS, BACKFIRE, HARD TO START & ROUGH/CHUGGLE

SUBJECT: ENGINE MISS, BACKFIRE, HARD START, ROUGH IDLE OR CHUGGLE - INSTALL NEW IGNITION COILS

VEHICLES AFFECTED: 1987-90 N, W AND L W/2.3L VIN D,A

CONDITION:

---------- Some 1987-90 N, W or L models equipped with 2.3L (VIN Code D or A) may exhibit engine miss, backfire, hard start, rough idle or chuggle. These conditions may be caused by the ignition coil. If diagnosis leads to the ignition coil it will be necessary to replace both.

The new type coils have a revised electrical connection tab that is yellow in colour to aid in identification. The internal metal pins were also revised for improved durability. These coils went into May 1990 vehicle Production. Following are VIN breakpoints for the vehicles involved.

RPO/VIN DIVISION CARLINE 1987 1988 1989 1990 ------ -------- ------- ---- ---- ---- --------------- LD2/D Buick N All All SOP to LM066531(NA5) LD2/D Oldsmobile N All All All SOP to LM767173(NA5) LD2/D Oldsmobile w SOP to LD400017(NA5) LD2/D Pontiac N All All All SOP to LC355448(NA5) LD2/D Pontiac w SOP to LF297772(NA5) LGO/A Chevrolet L SOP to LY227076(NA5) LGO/A Oldsmobile N SOP to LM766825(NA5) LGO/A oldsmobile w SOP to LD401389(NA5) LGO/A Pontiac N SOP to LC354777(NA5)

CORRECTION:

----------- Replace BOTH coils with package P/N #10457062. This package contains two coils.

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.