SERVICE MANUAL UPDATE SEC. 6E1 DRIVEABILITY AND EMISSION

SUBJECT: SERVICE MANUAL UPDATE - SECTION 6El DRIVEABILITY AND EMISSIONS REVISED ECM DWELL CALIBRATION

VEHICLES AFFECTED: 1987-88 B,F 5.OL, 5.7L ENGINES (VIN G,H,6)

This bulletin serves to revise information found in the 1987-1988 5.OL (VIN G/H) and 5.7L (VIN 6) "B" and "F" Carline Service Manuals, "Driveability And Emissions" Section 6El.

Some diagnostic steps require monitoring dwell for a value above 50 degrees. This value should not be used since the ECM limits dwell to a maximum of 45 degrees

When performing diagnostic checks using the following charts, replace the 50 degree dwell value with 45 degrees.

"System Performance Check" "Chart A-1" (Dwell Fixed Under 10 Degrees) "Chart A-2" (Dwell Fixed Between 11-50 Degrees) "Chart A-3" (Dwell Fixed Over 50 Degrees) "Code 44" (Lean Exhaust Indicated) "Code 45" (Rich Exhaust Indicated)

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.