COLD ENGINE KNOCKING NOISE (NEW SERVICE PROM)

VEHICLES AFFECTED: 1989 B-CAR (WITH FEDERAL EMISSION ONLY) W/5.0L

Condition:

---------- Some owners may comment of a cold engine knocking noise. This noise may be misdiagnosed as piston slap resulting in unnecessary engine replacement.

Cause:

------ The noise may be caused by detonation at ambient temperatures less than 4 degrees C (40 degrees F). Refined spark control tables in a new PROM specifically address this detonation condition.

Correction:

---------- Replace the PROM with the part number below:

New Part Number Broadcast Code New Scanner ID --------------- -------------- -------------- 16148142 ATYR 8031

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.