C 1500 Truck 2WD V6-262 4.3L VIN Z (1992)
condition, install the appropriate main bearings as determined by the following procedure.
Calibration Information - 1992-93 LB4 VIN Z
The revised PROMs reduce spark advance after the engine is started. The reduction in spark lowers the cylinder pressure and eliminates the knock. The
revised PROMs will NOT eliminate a piston slap (Category C) or valve train noise (Category B) concern. The base cold knock PROM contains the
previously released calibration updates. For 1992 LB4, the previous field release is included for torque converter clutch (TCC) lock up (see Bulletin
137107 - Chevrolet 92-75-7A; GMC Truck 92-7A-40; Oldsmobile 92-T-34; Canada 9274L60100) for automatic transmissions, or neutral gear rattle for
manual transmissions (see Bulletin 267201R - Chevrolet 92-187B-7B; GMC Truck 92-7B-149A; Canada 93-7B-105). If a vehicle has had a detonation
fix PROM installed previously, select the combined detonation and cold knock fix PROM for the application. See Bulletin 376508 for more information
on field fix PROM for the application and detonation.
Important:
Use of a detonation fix PROM in a non-detonating vehicle may result in degraded driveability.
GMSPO currently stocks three (3) PROMs for each light duty 1992 model year LB4 application.
Base
Cold Knock Fix
Combination Cold Knock and Detonation Fix
GMSPO Service Parts Assistance Center (SPAC 1-800-433-6961) will have information available on each PROM part number. Select the PROM from
the table. Old Broadcast Code (Old B/C Code) and Scan I.D. information has been supplied to help installed previously. Use a TECH-1 to determine the
Scan I.D. of the PROM in the vehicle or remove the PROM and read the Broadcast Code (B/C Code). If the B/C Code/Scan I.D. can be found in the first
table, a detonation fix has not been installed.
PROMs are currently available GMSPO.
1990-95 L05 VIN K
