EXHAUST ODOR SUMMARY BULLETIN (PROMS)

VEHICLES AFFECTED: 1986-88 M-VAN

Some 1986-87 and 1988 M-vans prior to Chevrolet VIN 191855 and 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 sustained 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 installation instructions.

See Table for applicable Labor Operations and Labor Time.

VEHICLE DESCRIPTION S E R V I C E I N F 0 R M A T I 0 N

MODEL EMMISIONS AXLE SERVICE PROM PROM I.D. BLEED PN YR FED/CALIF TRANS RATIO PROM KIT P/N LABEL (SCANNER) (IF APPLICABLE) -- --------- ----- ----- ------------ ----- --------- ---------------

1988 Federal A4 (MD8) All 16121142 AKMH 3051 Not Applicable

M5 (MH3) All 16120722 AKSP 3561 Not Applicable

1987 Federal A4 (MD8) All 16082087 AKDX 2261 10105820

M5 (MH3) 2.73 16088400 AKJL 8401 10105820

M5 (MH3) 3.08/ 16082103 AKFA 2291 10105820 3.42

1986 Federal A4 (MD8) All 16068877 ACHJ 9081 10093100

M5 (MH3) 2.56/ 16068942 ACHL 9101 10093100 2.73

M5 (MH3) 3.08/ 16068952 ACHN 9121 10093100 3.42

MODEL EMMISIONS AXLE Y-PIPE & PLUG P/N REFERENCE LABOR LABOR YR FED/CALIF TRANS RATIO (IF APPLICABLE) BULLETIN OPERATION TIME -- --------- ----- ----- --------------- -------- --------- ----

1988 Federal A4 (MD8) All Y-pipe 15598249 Plug 10017198 88-643-105 T7620 .9 hrs M5 (MH3) All Y-Pipe 15598249 Plug 10017198

1987 Federal A4 (MD8) All Not Applicable

M5 (MH3) 2.73 Not Applicable 88-643-103

M5 (MH3) 3.08/ Not Applicable 3.42

1986 Federal A4 (MD8) All Not Applicable

M5 (MH3) 2.56/ Not Applicable 2.73 87-643-107 T7430 .4 Hrs

M5 (MH3) 3.08/ Not Applicable 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.