Engine Performance - High Altitude Adjustment

85isuzu01
SB85-03-002 September 10, 1985 EMISSIONS

PERFORMANCE ADJUSTMENT FOR 1986 HIGH ALTITUDE FEDERAL LIGHT-DUTY GAS ENGINE TRUCKS

VEHICLES AFFECTED


1986 P'UP's with G200Z engine and 1986 Troopers with 4ZD1 engines.

SERVICE INFORMATION


Federal regulations provide for "Altitude Performance Adjustments" of in-use vehicles to improve engine performance at altitudes other than those for which the vehicles were designed. This bulletin establishes adjustment procedure and labeling requirements.

SERVICE PROCEDURE

Adjusting vehicle for principal use above 4,000 feet altitude:
1. Advance engine ignition timing up to 4 degrees from specification. Timing should not be advanced if spark knock occurs at high altitude.
2. Adjust engine idle speed to specification.
3. Install label 8-94422-536-0 under hood. Readjusting vehicle for principal use in low altitude areas below 4,000 feet:
1. Adjust engine to original specifications shown on original emission label under hood.
2. If high altitude label has been installed, remove it. (See "Adjustment Procedure," Par. 3 above).


LABEL AVAILABILITY


Labels are available from your facing Parts Distribution Center. Order part number 8944225360.

WARRANTY


This adjustment is not covered under warranty, owner must pay for any adjustments made.


ISUZU MOTORS LIMITED

VEHICLE EMISSION CONTROL INFORMATION UPDATE CERTAIN 1986 LOW ALTITUDE ISUZU VEHICLES HAVING PRINCIPAL USE ABOVE 4,000 FEET ELEVATION MAY BE ADJUSTED TO IMPROVE ENGINE PERFORMANCE AND EXHAUST EMISSION CONTROL. THIS LOW ALTITUDE VEHICLE HAS BEEN MODIFIED FOR HIGH ALTITUDE AS SHOWN BELOW. FOR SPECIFICATIONS, CONSULT THE APPROPRIATE SERVICE PUBLICATION AND THE VEHICLE EMISSION CONTROL INFORMATION LABEL FOR THIS VEHICLE.

^INITIAL ENGINE IGNITION TIMING ADVANCED UP TO 4 DEG FROM SPECIFICATION. TIMING SHOULD NOT BE ADVANCED IF SPARK KNOCK OCCURS AT HIGH ALTITUDE.

^ENGINE IDLE SPEED ADJUSTED TO SPECIFICATION.

THIS ENGINE MUST BE RETURNED TO ORIGINAL SPECIFICATIONS AND THIS LABEL REMOVED IF PRINCIPAL USE WILL BE BELOW 4,000 FEET ELEVATION OR IF SPARK KNOCK OR STALLING PROBLEMS OCCUR, PT. NO. 8944225360