Section I

Calibration MEM-CALS and Service Bulletins based on a customer complaint and/or condition.

CONDITION:

^ Codes 23, 25, 33, and/or 34 exist
^ Deceleration stall when exiting on a freeway ramp.
^ Stall after a steady highway driving during deceleration.
^ City traffic stalling, usually when vehicle is warm.
^ Repeated stalling until vehicle is parked and key is turned completely to the "OFF" position.
^ Engine will not start unless accelerator is partially depressed.
^ Engine stalls when driver's foot is removed from accelerator.
^ Engine stalls or sags when the vehicle is cold (first start of the day) or after the vehicle has been parked for a long period of time.
^ Intermittent stalling that cannot be duplicated by the technician.
^ Left or right turning maneuvers cause vehicle to stall, but cannot always be duplicated.
^ Engine RPM varies or fluctuates up and down after a cold start.
^ High engine RPM when de-clutching between shifts with a manual transmission.
NOTE: "MULTEC" fuel Injectors should not be cleaned.

CORRECTION:

1987- Mass Air Flow, to Speed
1988 Density update, Bulletin
Chev = 88-435-6E, Pont = 88-6-98C,
Olds = 88-T-147B, Buick = 88-6E-30A,
Cad = T-90-4A, Canada = 88-628-146
1988- J Carline Service Bulletin
Chev = 89-276-6E
1989 A, J, L, W Carline Service
Bulletin # : Chev = 89-276-6E,
Pont = 89-6-31A, Olds = 89-T-49A,
Buick = 89-6E-5, Cad = T-89-17A,
Canada = 89-631-107
1990 Service Bulletin # for "W" car only:
Chev = 90-81-6E,
Pont = 89-6-60
NOTE: After the condition has been corrected, follow the Idle Learn Procedure in "MISC. TEST" (F4) using the Tech 1 Scan Tool.

OTHER IMPORTANT CORRECTIONS:

^ 1987-1988 update MEM-CALS will update the Mass Airflow systems to Speed Density systems. This allows a faster response to RPM changes and a better overall idle control.
^ It is important that all components of the emission and engine controls are functioning properly before a new MEMCAL is installed. Example: A faulty MAP sensor can cause a rough, unstable idle or stalling problem.
^ General Motors' fuel injected engines control idle RPM by controlling airflow via the idle air control valve (IACV). It's important that the ECM knows the position of the IACV and THROTTLE ANGLE at all times.
^ The ECM uses throttle angle, coolant, IACV position, barometer, RPM, manifold pressure (MAP), A/C status, and steering position to calculate the proper idle RPM, ^ All of the above inputs should be checked, using a "Scan" tool, for correct operation after installing a new MEM-CAL. (Refer to Section III.)