ENG. STALL, LONG CRANKS/IDLE/ DECEL SURGE (DIAG. REPL. PROM). Buick Regal 1991

---------------------------------------------------------------------- THIS BULLETIN CANCELS AND SUPERSEDES CORPORATE BULLETIN 236512R. ----------------------------------------------------------------------

CONDITION:

SOME OWNERS OF 1990-93 J, L AND W CARS WITH THE 3.1L ENGINE MAY EXPERIENCE ENGINE STALLING, COLD START STALL AND BACK-UP STALLS. SOME OWNERS OF 1991-93 "W" CARS WITH A 3.4L DOHC ENGINE MAY EXPERIENCE A SLIGHT SURGE ON AN EXTENDED CLOSED THROTTLE DECEL WHEN EQUIPPED WITH AN AUTOMATIC TRANSMISSION; AND SOME OWNERS OF 1991-92 W-CARS WITH A 3.4L DOHC ENGINE AND MANUAL TRANSMISSION MAY EXPERIENCE COLD/HOT STALLS, DIAGNOSTIC TROUBLE CODE 32 AT HIGH ALTITUDE, OPEN LOOP DRIVE-AWAY SAGS AND/OR HESITATION.

CAUSE:

LOW VOLATILITY/HIGH DRIVEABILITY INDEX FUELS NOW SOLD IN THE MARKET PLACE AND ENGINE VARIABILITY CONDITIONS.

CORRECTION:

IF ANY OF THE SUBJECT CONDITIONS ARE EXPERIENCED, THEY MAY BE CORRECTED BY ENGINE CALIBRATIONS NOW AVAILABLE TO IMPROVE ENGINE OPERATIONAL STABILITY AND COLD (OPEN LOOP) DRIVEABILITY.

FOLLOWING PROCEDURE LISTED BELOW:

1. PERFORM DIAGNOSTICS, PER SECTION 6E OF THE SERVICE MANUAL. MAKE ANY ADJUSTMENTS, AS REQUIRED, OR REPLACE ANY DEFECTIVE PARTS ASSOCIATED WITH THE CAUSES DESCRIBED.

2. IF NO CAUSE FOR THE STALLING IS FOUND (USING NORMAL DIAGNOSTICS) AND THE CONDITIONS STILL EXIST, THEN REPLACE THE PROM WITH ONE FROM THE FOLLOWING TABLE (USING SERVICE MANUAL PROCEDURES):

1990-93 3.1 LITER HIGH DRIVEABILITY INDEX FUEL CALIBRATION SUMMARY ------------------------------------------------------------------

MODEL CAR ENG. B/C PROM SCANNER YEAR LINE RPO TRANS AXLE EMISSIONS CODE P/N I.D. ----- ---- --- ----- ---- --------- ---- ------- -------

92/93 J LH0 A-3 2.53 FEDERAL BFAD 16190126 0121 92/93 J LH0 A-3 2.53 CALIF. BFAF 16190129 0131 92/93 J LH0 A-3 2.84 FEDERAL BFAH 16190133 0141 92/93 J LH0 A-3 2.84 CALIF. BFAJ 16190137 0151 91 J LH0 A-3 2.53 FEDERAL BFAK 16190140 0161 91 J LH0 A-3 2.53 CALIF. BFAL 16190144 0171 91 J LH0 A-3 2.84 FEDERAL BFAM 16190147 0181 91 J LH0 A-3 2.84 CALIF. BFAN 16190150 0191 90 J LH0 A-3 2.53 FEDERAL BFAP 16190154 0201 90 J LH0 A-3 2.53 CALIF. BFAR 16190159 0211 90 J LH0 A-3 2.84 FEDERAL BFAS 16190163 0221 90 J LH0 A-3 2.84 CALIF. BFAT 16190166 0231 91/92/93 L LH0 A-3 2.53 + FEDERAL BFAU 16190170 0241 2.84 91/92/93 L LH0 A-3 2.53 + CALIF. BFAW 16190174 0251 2.84 90 L LH0 A-3 2.84 FEDERAL BFAX 16190177 0261 90 L LH0 A-3 2.84 CALIF. BFAY 16190180 0271 91/92/93 L LH0 M-5 3.61 FEDERAL BFUZ 16193199 3221 92/93 J LH0 M-5 3.61 FEDERAL BFUZ 16193199 3221 91/92/93 L LH0 M-5 3.61 CALIF. BFUY 16193196 3211 92/93 J LH0 M-5 3.61 CALIF. BFUY 16193196 3211 91 J LH0 M-5 3.61 FEDERAL BFUX 16193193 3201 91 J LH0 M-5 3.61 CALIF. BFUW 16193188 3191 90 J LH0 M-5 3.61 FEDERAL BBXU 16180435 0471 90 J LH0 M-5 3.61 CALIF. BBXW 16180437 0481 90 L LH0 M-5 3.61 FEDERAL BBFB 16178176 8251 90 L LH0 M-5 3.61 CALIF. BBDZ 16178174 8231 91/92/93 W LH0 A-3 2.84 FEDERAL BFBB 16190190 0301 91/92/93 W LH0 A-3 2.84 CALIF. BFBC 16190194 0311 90* W LH0 A-3 2.84 FEDERAL BFBK 16190212 0361 90* W LH0 A-3 2.84 CALIF. BFBL 16190215 0371 93 W LH0 A-4 3.33 FEDERAL BDJS 16186544 6551 93 W LH0 A-4 3.33 FEDERAL BFBP 16190225 0401 (POLICE) 91/92** W LH0 A-4 3.33 FEDERAL BFBD 16190197 0321 91/92 W LH0 A-4 3.33 CALIF. BFBF 16190200 0331 91/92 W LH0 A-4 3.33 FEDERAL BFBH 16190205 0341 (POLICE) 91/92 W LH0 A-4 3.33 CALIF. BFBJ 16190208 0351 (POLICE) 90* W LH0 A-4 3.33 FEDERAL BFBM 16190218 0381 90* W LH0 A-4 3.33 CALIF. BFBN 16190222 0391

*NOTE: THESE PARTS CANNOT BE USED ON VEHICLES THAT DO NOT HAVE DIGITAL EGR (EXHAUST GAS RECIRCULATION) VALVES.

**NOTE: 1991 BUICK REGAL SEDANS WITH 3.1L ENGINES BUILT PRIOR TO VIN SEQUENCE 800,000 SHOULD HAVE THE 1990 BUICK REGAL PROMS INSTALLED.

1991-93 3.4 LITER DRIVEABILITY CALIBRATION SUMMARY ------------------------------------------------------------------

MODEL CAR ENG. B/C PROM SCANNER YEAR LINE RPO TRANS TIRES EMISSIONS CODE P/N I.D. ----- ---- --- ----- ----- --------- ---- ------- -------

91-93 W LQ1 A-4 QNX FEDERAL BHAH 16194248 4281 91-93 W LQ1 A-4 QNX CALIF. BHAJ 16194253 4291 91-93 W LQ1 A-4 QXJ FEDERAL BHAK 16194256 4301 91-93 W LQ1 A-4 QXJ CALIF. BHAL 16194259 4311 91-92*** W LQ1 M-5 ALL NATIONAL BCFA 16181397 1441

***NOTE: 1991 "W" CARS (MANUAL TRANSMISSIONS ONLY) SHOULD BE UPDATED WITH THE CLUTCH ANTICIPATE SWITCH PER CORPORATE SERVICE BULLETIN 136526.

PART AVAILABILITY:

PARTS ARE EXPECTED TO BE AVAILABLE FROM GMSPO ON 9/13/93.

WARRANTY INFORMATION:

LABOR OPERATION: T-0500 LABOR TIME: 0.8 HR.

FIGURES: 0

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.