K 1500 Truck 4WD V8-454 7.4L (1988)
Idle Speed: Customer Interest
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.
2. On 1987-89 models, check base timing (Spec. 4 degrees BTDC).
View A
