DRIVEABILITY IMPROVEMENTS (REPLACE PROM). Buick Coachbuilder 1991

For 1990-2009 cars

# DRIVEABILITY IMPROVEMENTS (REPLACE PROM)

#### SUBJECT: DRIVEABILITY IMPROVEMENTS (REPLACE PROM)

#### VEHICLES AFFECTED: 1991-93 "B" AND 1991 "D" CARS WITH 5.0L AND 5.7L ENGINES (RPOS L03 AND L05)

THIS BULLETIN SUPERSEDES AND REPLACES CORPORATE BULLETINS REFERENCE NUMBER 276110R.** THIS BULLETIN IS BEING REVISED TO ADD 1993 MODEL YEAR VEHICLES FOR BROADCAST CODE BCDU, SCANNER I.D. 1391, P/N 16181390, 5.0L B CARS.

#### CONDITION:

--------- Some owners of 1991-1993 model year B and 1991 model year D cars with either the L03 (VIN E, 5.0L V8) or L05 (VIN 7 5.7L V8) engine may comment on low speed driveability or engine detonation (spark knock).

#### CORRECTION:

---------- The calibrations have been refined to address these concerns. If, after completing normal diagnostics, the condition remains, replace the PROM with the appropriate one from the table below:

#### NOTE: For L03 B-car only, make certain the vehicle has been updated with the previously attempted service fixes as follows.

Description Part Number ----------- ----------- EGR Valve 17090156 (Stamped on Valve) 17112373 (GMSPO Kit)

PCV Valve 25098542

ESC Module 16175099 Broadcast Code (BARC)

Broadcast Scanner Part Model Code I.D. Number Year Body Application --------- ------- ------ ----- ---- ----------- AXHR 0531 16160477 1991 D 5.0L L03 Nationwide emissions

AXDA 9971 16159963 1991 D 5.7L L05 Nationwide emissions

AXDF 9984 16159983 1991 D 5.7L L05 Export (Leaded Fuel)

AYMJ 5941 16165912 1991 B 5.0L L03 Wagon California emissions

AYMK 5951 16165913 1991 B 5.0L L03 Sedan California emissions

AYKA 5301 16165380 1991 B 5.0L L03 Police Sedan Federal emissions

AYKB 5311 16165384 1991 B 5.0L L03 Public Service Wagon Federal emissions

BATJ 5901 16175898 1991/92 B 5.7L L05 Sedan and Wagon - Nationwide emissions

BCDU 1391 16181390 1991/93 B 5.0L L03 Sedan and Wagon - Federal emissions

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.