LACK OF POWER, HES, OR FLAT SPOT ON ACCELERATION

Model and Year: 1988 S/T TRUCKS WITH 4.3L (VIN CODE Z) ENGINE AND CALIFORNIA EMISSIONS

Customer comments of lack of performance, poor tip-in response, or engine flatness may be received in connection with some early built S/T trucks with a 4.3L engine and california emissions. A new prom was put into production that addresses these concerns. This new prom is now available for trucks built before the following breakpoints:

172008

The new PROM, part number for the LB4 (4.3L) engine is listed below:

New New Broadcast PROM Emiss. New PROM Code I.D. Type Trans. Axle Kit # PROM Label Scan Tool ---------------------------------------------------------------- Calif 4-Spd. GU4 (3.08) 16124986 ANKB 5551 (NB2) Auto (MD8) GU6 (3.42)

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.