Suburban 1/2 Ton 2WD V8-454 7.4L (1987)
View E
E.
Add one additional 3/16" hole to plastic bracket and two 1/8" holes in Air Cleaner proper location using revised bracket as hole template
(See View C and D).
F.
Mount bracket so Map Sensor vacuum connection faces down toward engine, using two 8-3x1/2" sheet metal screws, P/N 447164.
G.
Install vacuum hose harness, P/N 10129600 (See View D and E).
IMPORTANT:
On trucks not equipped with an accessory vacuum fitting in the manifold, install fitting, P/N 14088336 and use caps, P/N 343350 to plug any
unused port.
H.
Reinstall electrical.
4.
On 1987-89 Check Control Idle Speed
A.
On fully warm engine, Spec. is 750 RPM in Drive for Automatic Transmission and 800 RPM in Neutral for Manual Transmission.
B.
IAC counts on both transmission should be between 5-30 counts.
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
