Suburban 1/2 Ton 2WD V8-454 7.4L (1987)
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 # 89263A6E
Date: 911101
PROM - Surge, Detonation or Code 32, EGR
Number: 89-263A-6E
Section: 6E
Date: NOV. 1991
Corporate Bulletin No.: 136516
ASE No.: A1 & A8
Subject:
ENGINE DRIVEABILITY - SURGE HOT/COLD, DETONATION
Model and Year:
1987-89 C/K, R/V AND G/P TRUCKS WITH 7.4L ENGINE
THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NUMBERS 88-162-6E, DATED AUGUST 1988; 88-195-6E,
DATED MAY 1988; AND 89-263-6E, DATED OCTOBER 1989. ALL COPIES OF 88-162-6E, 88-195-6E AND 89-263-6E SHOULD BE
DISCARDED.
Condition:
Some owners of 1987-89 C/K, R/V and 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
Correction:
1.
On 1987-89 models, check for vacuum leaks including:
