High Altitude - Adjustment Procedure

BT82-012

NOVEMBER 17, 1982


EMISSION CONTROLS/EXHAUST

PERFORMANCE ADJUSTMENT FOR 1983 HIGH ALTITUDE PASSENGER CARS AND LIGHT-DUTY TRUCKS (EXCEPT DIESEL)


SERVICE INFORMATION

Federal Regulations provide for "Altitude Performance Adjustments" of new and in-use vehicles, to improve emission control performance at altitudes other than those for which the vehicles were designed. (Over 4000 ft.). This Bulletin establishes the adjustment procedure and labeling requirements.

VEHICLES AFFECTED

All 1983 Passenger Cars and Light-Duty trucks, (except diesel), sold at altitudes less than 4000 ft., but driven principally in High Altitude areas and all 1983 Passenger Cars and Light-Duty Trucks modified or adjusted for High Altitude Performance, but driven principally in Low Altitude areas.

ADJUSTMENT PROCEDURE

Adjusting Low Altitude vehicle for principal use over 4000 ft. altitude.

1. Advance engine ignition timing up to 4~ from specification. Timing should not be advanced if spark knock occurs at Hiqh Altitude.

2. Adjust engine speed to specification.

3. Install Label P/N 2-91024-001-0 under hood.

Adjusting High Altitude Vehicle for principal use in Low Altitude areas under 4000 ft.:

1. Adjust engine to original specifications shown on Emission Label under hood.

2. If Label has been installed, remove it. (See "Adjustment. Procedure" paragraph 3).

LABEL AVAILABILITY

Five labels are attached to this Bulletin. Additional labels are available from your Regional Office.

WARRANTY

This is not a warranty item. Owner to pay for adjustment.