EXHAUST ODOR SUMMARY BULLETIN (PROMS)

MODELS: 1986-88 M VAN WITH 4.3 L ENGINE (VIN CODE Z)

Some 1986-87 and 1988 M-vans prior to GMC VIN 523374 equipped with 4.3L (VIN Code Z) engines may exhibit an exhaust odor often described as sulfur or rotten egg smell at idle following sus- tained highway driving or trailer towing.

This bulletin includes a table which summarizes the various service fixes intended to address this condition depending on the model year of the vehicle.

The table lists the appropriate service procedures, calibration PROM, applicable service parts and a bulletin number to reference for complete in- stallation instructions.

See Table for applicable Labor Operations and Labor Time.

VEHICLE DESCRIPTION SERVICE INFORMATION

Model Emissions Axle Service Year Fed/Calif Trans Ratio Prom Prom Prom I.D. Bleed PN ---- --------- ----- ----- ------- ---- --------- --------- 1988 Federal A4(MD8) All 16121142 AKMH 3051 Not Applicable

M5(MH3) All 16120722 AKSP 3561 Not Applicable

Calif. A4(MD8) All 16121146 AKW 3061 Not Applicable

M5(MH3) All 16120727 AKSR 3571 Not Applicable

1987 Federal A4(MD8) All 16082087 AKDX 2261 10105820 M5(MH3) 2.73 16088400 AWL 8401 10105820 M5(MH3) 3.08 16082103 AKFA 2291 10105820 /3.42

Calif. A4(MD8) All 16088362 AMDA 8351 10105820 M5(MH3) 2.73 16087025 AMBS 7261 10105820 M5(MH3) 3.08 16087020 AMBR 7251 10105820 /3.42

1986 Federal A4(MD8) All 16068877 ACHJ 9081 10093100 M5(MH3)2.56/2.73 16068942 ACHL 9101 10093100 M5(MH3)3.08/3.42 16068952 ACHN 9121 10093100

Calif. A4(MD8) All 16068926 ACHK 9091 10093100 M5(MH3)2.56/2.73 16068946 ACHM 9111 10093100 M5(MH3)3.08/3.42 16068956 ACHP 9131 10093100

Model Emissions Axle Y-Pipe &Plug P/N Reference Labor Labor Year Fed/Calif Trans Ratio (If Applicable) Bulletin Op. Time ----- --------- ----- ----- ---------------- --------- ------ ----- 1988 Federal A4(MD8) All Y-pipe 15598249 Plug 10017198 T&B88-T-126 T7620 .9 Hrs. M5(MH3) All Y-pipe 15598249 Plug 10017198

Calif. A4(MD8) All Y-pipe 15598249 Plug 10017198 T&B88-T-126 T7620 .9 Hrs. M5(MH3) All Y-pipe 15598249 Plug 10017198

1987 Federal A4(MD8) All Not Applicable M5(MH3) 2.73 Not Applicable T&B88-T-119 T7455 .5 Hrs. M5(MH3) 3.08 Not Applicable /3.42

Calif. A4(MD8) All Not Applicable M5(MH3) 2.73 Not Applicable T&B 88-T-119 T7455 .5 Hrs. M5(MH3) 3.08 Not Applicable /3.42

1986 Federal A4(MD8) All Not Applicqible M5(MH3)2.56/2.73 Not Applicable T&B 86-T-151 T7430 .4 Hrs. M5(MH3)3.08/3.42 Not Applicable

Calif. A4(MD8) All Not Applicable M5(MH3)2.56/2.73 Not Applicable T&B 86-T-151 T7430 .4 Hrs. M5(MH3)3.08/3.42 Not Applicable

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.