ENG. MISS AT IDLE/HIGHWAY SPEED, INSTALL NEW SPARK PLUGS

SUBJECT: ENGINE MISS AT IDLE AND/OR AT HIGHWAY SPEED (INSPECT, INSTALL NEW SPARK PLUGS)

VEHICLES AFFECTED: 1989-90 A,N, MODELS W/3300 (VIN N) ENGINE

Some 1989-1990 "A and N" models equipped with a 3300 engine (VIN N), may experience a condition described as an engine miss at idle and or at highway speed.

If these conditions are experienced on a vehicle, technicians should inspect all spark plugs for a broken insulator, as shown in Figure 1. Condition occurs most often on cylinders 2, 4 or 6. Should a technician find a broken insulator on any cylinder, it is recommended that all spark plugs be replaced with a new replacement spark plug R45LTS6, Service Package Number 5614224. This Service Package will also serve as the new service replacement spark plug for the 1989-1990 3300 (VIN N) engine, S.O.P. 1991 vehicles were changed to the new spark plug, R45LTS6.

NOTE: Spark plugs must be replaced as a set, do not mix spark plugs.

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.