K 2500 Truck 4WD V8-454 7.4L (1990)
PROM - Programmable Read Only Memory: Customer Interest
Engine - Detonation/Sulfur Odor From Exhaust
GMC NUMBER:
90-6F-125
GROUP:
6F Engine Exhaust
DATE:
July, 1991
CORPORATE
NUMBER:
136511
SUBJECT:
DETONATION AND/OR EXHAUST ODOR (INSTALL NEW PROM)
MODELS:
1990 C/K, R/V, G, and P TRUCKS WITH 7.4L ENGINES (ABOVE 8600 GVW)
Condition:
Some owners of 1990 trucks with the 7.4L engine may comment of either detonation at highway speeds or exhaust odor (sulfur smell) at
idle.
Cause:
The original spark advance and idle calibration may generate detonation or sulfur odor comments for a few isolated conditions.
Correction:
On trucks where these conditions can not be repaired using normal service procedures, a revised calibration PROM should be installed (see
below).
Part Number
Emission System
Trans.
PROM Broadcast
Scanner ID
16165446
NA4 (above 8600 GVW)
M40 (Auto)
AYKK
5451
16165447
NA4 (above 8600 GVW)
M20 (Manual)
AYKL
5461
Labor Operation Number:
T0500
Labor Time:
.6 Hour
