For 1990-2009 cars

# EXHAUST ODOR AND OTHER FUEL RELATED CONCERNS

REVISED: 05/08/95

THIS BULLETIN IS BEING REVISED TO INFORM "GM OF CANADA" AND "NAES" DEALERS THAT THEY ARE NOT AUTHORIZED TO UTILIZE THIS SERVICE BULLETIN. ----------------------------------------------------------------------

"GM OF CANADA" AND "NAES" DEALERS ARE NOT AUTHORIZED TO UTILIZE THIS SERVICE BULLETIN.

#### SUBJECT: EXHAUST ODOR AND OTHER FUEL RELATED CONCERNS (USE KNOWN GOOD QUALITY FUEL)

#### MODELS: 1990-1993 CADILLAC DEVILLE, FLEETWOOD, SIXTY SPECIAL (FWD) 1990-1993 CADILLAC ALLANTE 1990-1994 CADILLAC ELDORADO, SEVILLE 1994 CADILLAC DEVILLE, DEVILLE CONCOURS (WITH 4.5L, 4.6L OR 4.9L ENGINES)

#### CONDITION:

SOME 1990-1994 VEHICLES THAT REQUIRE PREMIUM FUEL USAGE MAY EXPERIENCE ONE OR MORE OF THE FOLLOWING INTERMITTENT DRIVEABILITY CONDITIONS:

O EXHAUST ROTTEN EGG ODOR OR SULFUR ODOR. O POOR COLD ENGINE OPERATION: NO START/HARD START, START/STALL AT IDLE. O HOT RESTART PROBLEMS. O ROUGH/MISS AT IDLE. O HESITATION AND/OR LACK OF POWER. O DETONATION.

#### CAUSE:

THESE CONDITIONS MAY OCCUR DUE TO THE FUEL IN THE VEHICLE. POOR FUEL QUALITY HAS BEEN RECOGNIZED TO CAUSE ANY OF THE CONDITIONS LISTED ABOVE. HIGH SULFUR CONTENT FUEL HAS BEEN RECOGNIZED TO CAUSE EXHAUST ROTTEN EGG ODOR OR SULFUR ODOR CONDITIONS. OXYGENATED FUELS WHICH ARE USED IN MANY AREAS OF THE COUNTRY MAY HAVE A DISTINCTIVE ODOR. THIS IS CONSIDERED NORMAL, AND IS NOT RELATED TO THE EXHAUST "ROTTEN EGG" ODOR.

THE OBJECTIVE OF OXYGENATED FUELS IS TO REDUCE TAIL PIPE EMISSIONS OF CARBON MONOXIDE. CARBON MONOXIDE IN THE ATMOSPHERE, ESPECIALLY DURING WINTER MONTHS WHEN IT IS AT ITS HIGHEST LEVELS, CAN AFFECT THE HEALTH OF PEOPLE WITH HEART DISEASE AND RESPIRATORY PROBLEMS. THE OXYGENATED FUELS CONTAIN OXYGEN COMPOUNDS THAT MAKE COMBUSTION MORE EFFICIENT WHILE LOWERING CARBON MONOXIDE LEVELS IN THE ATOMSPHERE.

THE FEDERAL CLEAN AIR ACT AMENDMENT OF 1990 REQUIRES THE USE OF OXYGENATED FUEL IN NEARLY ALL CARBON MONOXIDE NON-ATTAINMENT AREAS IN THE UNITED STATES. THE PROGRAM BEGAN LAST WINTER IN CERTAIN NON-ATTAINMENT AREAS. THESE REGULATIONS WILL CONTINUE IN FUTURE YEARS WITH WINTERTIME FUEL STARTING, IN SOME CASES, AS EARLY AS THE BEGINNING OF SEPTEMBER AND ENDING AS LATE AS APRIL DEPENDING UPON THE AREA OF THE COUNTRY.

#### CORRECTION:

IN ORDER TO DETERMINE IF FUEL IS A POSSIBLE CAUSE OF THE ABOVE LISTED DRIVEABILITY CONCERNS, USE THE FOLLOWING PROCEDURE AS A CHECKLIST:

1. VERIFY FROM THE CUSTOMER WHEN THEY FIRST STARTED NOTICING CONDITION (I.E., AFTER CHANGING FUEL BRANDS).

2. CHECK FOR PCM DIAGNOSTIC TROUBLE CODES SET. DIAGNOSE AND REPAIR ALL CAUSES OF PCM DIAGNOSTIC TROUBLE CODES SETTING, THEN RE-EVALUATE VEHICLE.

3. PERFORM BASIC SYSTEM CHECKS OUTLINED IN SECTION 6E-B (EXCESSIVE EXHAUST EMISSIONS - ODORS) OF THE APPROPRIATE SERVICE INFORMATION MANUAL.

4. FOR 1990-1992 VEHICLES, PERFORM CORPORATE BULLETIN 016511R (CADILLAC T-92-76 AND GM OF CANADA 93-6E-104) IN GROUP 6E.

5. IF THE ABOVE STEPS ARE INEFFECTIVE, DO NOT PROCEED WITH ADDITIONAL VEHICLE DIAGNOSIS AND/OR PARTS REPLACEMENT UNTIL THE FUEL TANK HAS BEEN DRAINED AND REFILLED WITH A KNOWN GOOD QUALITY GASOLINE AT THE DEALERSHIP.

6. IF THESE STEPS DO NOT ELIMINATE THE CONDITION, TAIL PIPE EMISSIONS MEETS EMISSIONS COMPLIANCE, AND THE VEHICLE IS OPERATING TO SPECIFICATIONS AFTER FOLLOWING THE PROCEDURE, THEN THE VEHICLE IS CONSIDERED TO BE NORMAL.

IF FUEL IS DETERMINED TO BE THE CAUSE OF THE ABOVE LISTED DRIVEABILITY CONDITIONS OR THE VEHICLE IS CONSIDERED TO BE NORMAL, THEN USE THE LABOR OPERATION LISTED BELOW FOR DIAGNOSIS TIME ONLY. THIS WILL ENHANCE THE RESEARCH DATA IN EVALUATING THE IMPACT OF FUEL.

IF FUEL IS NOT THE CAUSE OF THE ABOVE DRIVEABILITY CONDITIONS DO NOT USE THIS LABOR OPERATION, USE THE CORRESPONDING LABOR OPERATION FOR WHAT CAUSED THE CONDITION.

#### WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE: LABOR OPERATION T6772 AT .2 HOUR.

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.

COPYRIGHT 1993 CADILLAC MOTOR CAR DIVISION, GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.