COLD ENGINE KNOCKING NOISE (NEW SERVICE PROM)

Model and Year: 1989 B CAR WITH 5.0L (VIN CODE E) ENGINE FEDERAL EMISSIONS ONLY

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

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

Replace the PROM with the part number below:

New Part Number Broadcast Code New Scanner ID --------------- -------------- --------------

16148142 ATYR 8031

Parts are currently available from GMSPO.

Labor Operation Number: T0500

Labor Time: .5 hours

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.