R 3500 P/U 2WD V8-454 7.4L VIN W 4-bbl (1988)
If the control speed is not within the above specifications, a minimum idle speed adjustment must be made using procedure shown on Page 4-20 of the
1991 Fuel and Emission Manual.
5.
Install latest PROM as shown on chart.
New
New
PROM
Broadcast
New
Scan
Transmission
Axle
Kit
Code
Tool I.D.
Auto (M-40)
ALL
16169157
AZFT
9171
Man (M-20)
3.73 (GT4)
16169158
AZFU
9181
3.42 (GU6)
"
"
"
Man (M-20)
4.10 (GT5)
16169159
AZFW
9191
4.56 (HC4)
"
"
"
6. The Dealer should tell the customer that the Cold Start Procedure has been revised from that shown in his Owners Manual. After initial fire and run,
the throttle should be cracked to about 1/4 to clean raw gas from the intake manifold.
Labor Operation Number:
Labor Time
Relocating Map Sensor
T7500
0.3 Hours
Replace PROM
T0500
0.6 Hour C/K, R/V
0.7 Hour G/P
Technical Service Bulletin # 896E140
Date: 911101
Fuel - Diagnosis for Surge Hot/Cold, Detonation, Code 32
GMC NUMBER:
89-6E-140
GROUP:
6E Engine Emissions
DATE:
November, 1991
CORPORATE NUMBER: 136516
SUBJECT:
ENGINE DRIVEABILITY - SURGE HOT/COLD, DETONATION (DIAGNOSIS, REPLACEMENT PARTS)
MODELS:
1987-89 C/K AND R/V/G/P WITH 7.4L ENGINE
THIS CANCELS AND REPLACES THE FOLLOWING GMC TRUCK BULLETINS:
88-T-141 (AUG 88), 88-T-95 (APR 88), AND 89-6E-106 (OCT 89). ALL COPIES OF THESE BULLETINS SHOULD BE DESTROYED.
Some 1987-89 C/K and R/V/G/P trucks with 7.4L engine may experience the following:
1. Surge on acceleration and/or at road load speeds
2. False Service Engine Soon Light - Code 32 (EGR)
3. Poor driveability during warm up
4. Detonation under load
SERVICE PROCEDURE:
1. On 1987-89 models, check for vacuum leaks including;
A. TBI Base gasket to adapter
B. TBI Adapter to TBI
C. Re-torque intake manifold to 30 lbs.ft.