Engine - Altitude Performance Adjustments
83amcjeep01AUGUST 1983 000 061
1983 JEEP VEHICLES
11E
ENGINE Attention: Workshop, Parts Department.
ALTITUDE PERFORMANCE ADJUSTMENTS
Information
This I.S. Note provides information on improving the performance of 1983 Jeep vehicles being operated at altitudes above or below that which the engine was originally certified for and adjusted to.
When necessary, perform the engine adjustments outlined in the Adjustment Procedures portion of this I.S. Note. In addition, any Jeep vehicle that is so adjusted must have a unique Emission Control Information Update label installed. The part numbers for these unique labels are provided in the following Adjustment Procedures.
The adjustment procedures and unique labels must be made available at no cost to independent repair facilities and the general public. A notification is also provided in current owner's manuals to make customers aware of these adjustments. The Emission Control Information Update labels and technical information are available through our distribution facility:
Distribution Services 37200 Amrhein Road Livonia, Michigan 48150
ADJUSTMENT PROCEDURES
1. 2.5 LITER FOUR-CYLINDER MODELS
2. SIX-CYLINDER AND 2.46 LITER FOUR-CYLINDER MODELS
3. EIGHT-CYLINDER MODELS
1. 2.5 LITER FOUR-CYLINDER MODELS
On 1983 2.5L four-cylinder Jeep models originally certified for operation at altitudes below 4,000 feet that are being operated above 4,000 feet, the ignition timing, as shown on the Vehicle Emission Control Information label in the engine compartment, should be advanced 7~ and the engine idle speed should be reset to the specification shown on the same label.
1. Advance ignition timing 7~ from the setting specified on the original Vehicle Emission control Information label and reset engine idle speed to the setting indicated on the same label.
2. Install Vehicle Emission Control Information Update label, part number 89 83 100 009, next to the original label.
These adjustments apply to all 1983 2.5L four-cylinder Jeep models that were originally certified for principal use at altitudes below 4,000 feet. Refer to the Vehicle Emission Control Information label in the engine compartment to identify these vehicles.
NOTE: Whenever these vehicles are returned to operation at altitudes below 4,000 feet, the ignition timing and engine idle speed must be reset to original specifications and the Vehicle Emission Control Information Update label removed.
On 1983 2.5L four-cylinder Jeep models originally certified for operation at altitudes above 4,000 feet that are being operated below 4,000 feet, the ignition timing as shown on the Vehicle Emission Control Information label in the engine compartment, should be retarded 7~. The engine idle speed reset to the specifications shown on the same label.
1. Retard the ignition timing 7~ from the setting specified on the original Vehicle Emission Control Information label and reset engine idle speed to the setting indicated on this same label.
2. Install Vehicle Emission Control Information Update label, part number 89 83 100 010, next to the original label.
These adjustments apply to all 1983 four-cylinder Jeep models that were originally certified for principal use at altitudes above 4,000 feet. Refer to the Vehicle Emission Control Information label in the engine compartment to identify these vehicles.
NOTE: Whenever these vehicles are returned to operation at altitudes above 4,000 feet the ignition timing and engine idle speed must be reset to original specifications and the Vehicle Emission Control Information Update label removed.
2. SIX-CYLINDER AND 2.46 LITER FOUR-CYLINDER MODELS
On 1983 six-cylinder and 2.46L four-cylinder Jeep models originally certified for operation at altitudes below 4,000 feet that are being operated above 4,000 feet, the ignition timing as shown on the original Vehicle Emission Control Information label in the engine compartment, should be advanced 7~ and engine idle speed reset to the specifications indicated on this same label. In addition, the altitude circuit ground wire must be untaped from the MCU harness in the engine compartment and connected to a ground screw on the engine.
1. Remove the tape securing the black with tracer altitude circuit ground wire to the MCU harness.
2. Attach the altitude circuit ground wire to the engine ground screw near the ignition coil.
NOTE: The existing engine ground wires are also attached to this ground screw.
3. Advance ignition timing 7~ from the setting indicated on the original Vehicle Emission Control Information label and reset engine idle speed to the setting indicated on the same label.
4. Install Vehicle Emission Control Information Update label, part number 89 83 100 009, next to the original label.
These adjustments apply to all 1983 six-cylinder and 2.46L four-cylinder Jeep models originally certified for principal use at altitudes below 4,000 feet. Refer to the Vehicle Emission Control Information label in the engine compartment to identify these vehicles.
NOTE: Whenever these vehicles are returned to operation at altitudes below 4,000 feet the ignition timing and engine idle speed must be reset to original specifications, the altitude circuit ground wire must be disconnected and the Vehicle Emission Control Information Update label removed.
On 1983 six-cylinder and 2.46L four-cylinder Jeep models originally certified for operation at altitudes above 4,000 feet that are being operated below 4,000 feet, the ignition timing as shown on the original Vehicle Emission Control Information label in the engine compartment should be retarded 7~ and engine idle reset to the specification indicated on this same label. In addition, the altitude circuit ground wire must be disconnected and taped to the MCU harness.
1. Disconnect the black with tracer altitude circuit ground wire from the engine ground screw near the ignition coil. Tape the wire to the MCU harness securely and be sure the wire eyelet is completely covered with tape.
2. Retard ignition timing 7~ from the setting indicated on the original Vehicle Emission Control label and reset engine idle speed to the setting indicated on this same label.
3. Install Vehicle Emission Control Information Update label, part number 89 83 100 010, next to the original label.
These adjustments apply to all 1983 six-cylinder and 2.46L four-cylinder Jeep models that were originally certified for principal use at altitudes above 4,000 feet. Refer to the Vehicle Emission Control Information label in the engine compartment to identify these vehicles.
NOTE: Whenever these vehicles are returned to operations at altitudes above 4,000 feet, the ignition timing and engine idle speed must be reset to original specifications and the altitude circuit ground wire reconnected and the Vehicle Emission Control Information Update label removed.
3. EIGHT-CYLINDER MODELS
On 1983 eight-cylinder Jeep models originally certified for operation at altitudes below 4,000 feet that are being operated above 4,000 feet, the ignition timing, as shown on the Vehicle Emission Control Information label in the engine compartment, should be advanced 5~ and the engine idle speed reset to the specification shown on the same label.
1. Advance ignition timing 5~ from the setting indicated on the original Vehicle Emission Control Information label and reset engine idle speed to the setting indicated on the same label.
2. Install Vehicle Emission Control Information Update label, part number 89 83 100 009, next to the original label.
These adjustments apply to all 1983 eight-cylinder Jeep models that were originally certified for principal use at altitudes below 4,000 feet. Refer to the Vehicle Emission Control Information label in the engine compartment to identify these vehicles.
NOTE: Whenever these vehicles are returned to operation at altitudes below 4,000 feet, the ignition timing and engine idle speed must be reset to original specifications and the Vehicle Emission Control Information Update label removed.
On 1983 eight-cylinder Jeep models originally certified for operation at altitudes above 4,000 feet that are being operated below 4,000 feet, the ignition timing as shown on the Vehicle Emission Control Information label in the engine compartment, should be retarded 5~ and the engine idle speed reset to the specifications shown on same label.
1. Retard the ignition timing 5~ from the setting shown on the original Vehicle Emission Control Information label and reset engine idle speed to the setting indicated on the same label.
2. Install Vehicle Emission Control Information Update label, part number 89 83 100 010, next to the original label.
These adjustments apply to all 1983 eight-cylinder models that were originally certified for principal use at altitudes above 4,000 feet. Refer to the Vehicle Emission Control Information label in the engine compartment to identify these vehicles.
NOTE: Whenever these vehicles are returned to operations at altitudes above 4,000 feet, the ignition timing and engine idle speed must be reset to original specifications and the Vehicle Emission Control Information Update label removed.
Filing Instructions
File this I.S. Note in the plastic binder supplied with Supplement No. 1 to the 1982 Jeep Technical Service Manual.