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

SUBJECT: ENGINE MISS AT IDLE AND/OR AT HIGHWAY SPEED

MODELS AFFECTED: 1989 - 90 CENTURY WITH 3300 (VIN N) 1989 - 90 SKYLARK WITH 3300 (VIN N)

Some 1989 - 90 Century and Skylark 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, (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.

Parts are expected to be available on October 10, 1990. Until then normal part orders will not be accepted by GMSPO. Only verifiable emergency VIP orders will be accepted. GMSPO will make every effort to obtain parts. All parts will be placed on 400 control to waive VIP surcharges. However, the part will be shipped premium transportation at dealer's expense. All other order types will be canceled as incorrectly ordered while the 400 control is in place.

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.