Engine Controls - Revised ECM Dwell Calibration

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Number: 88-444-6E

Section: 6E

Date: December 1990

Corporate Bulletin No.: 016550


Subject: REVISED ECM DWELL CALIBRATION


Model and Year: 1987-88 CAPRICE AND CAMARO WITH 5.0L AND 5.7L ENGINES


TO: ALL CHEVROLET DEALERS

This bulletin serves to revise information found in the 1987-1988 5.0L (VIN G/H) and 5.7L (VIN 6) "B" and "F" Carline Service Manuals, "Driveability And Emissions" Section 6E1.

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)