4.1985 Eagle - CJ/Scrambler - Grand Wagoneer/Truck 4.2L Engine

For 1985, Eagle/Jeep 49-State/California/ Canada 4.2L engines require altitude adjustment. However, the method of adjustment for automatic or manual transmission equipped models are different as outfined in the following procedures.


49-State/California/Canada 4.2L Engine Adjustment - Automatic Transmission


On 1985 Eagle/Jeep, 49-State/California/ Canada 4.2L models with automatic transmission, originally sold for operation at altitudes below 4,000 feet that are being operated above 4,000 feet, the ignition timing must be advanced 7~ and engine idle speed reset. In addition, a jumper wire must be added to the MCU circuit to activate the altitude compensating circuit in the MCU.


1. Move the carpeting away from the passenger front seat toeboard to expose the MCU harness.


2. Untape the two-terminal connector from the MCU harness.


3. Connect jumper wire, P/N 318 6890, to the two-terminal connector and reinstall the carpet.


4. Advance ignition timing 7~ from the setting indicated on the original Vehicle Emission Control Information label in the engine
compartment and reset the engine idle speed to the setting indicated on the same label.


5. Install Vehicle Emission Control Information Update label, P/N EF 8980 000 743, next to the original label.


These adjustments apply to 1985 Eagle/Jeep, 49-State/California/Canada 4.2L models with automatic transmissions originally sold for principal use at altitudes below 4,000 feet. Refer to the Vehicle Emission Control Information label to identify these vehicles.


NOTE: Whenever these vehicles are returned to operation at altitudes below 4,000 feet, the MCU circuit jumper wire must be removed, the ignition timing and engine idle speed must be reset to original specifications and the Vehicle Emission Control Information Update label removed.


On 1985 Eagle/Jeep, 49-State/California/ Canada 4.2L models with automatic transmission originally sold for operation at altitudes above 4,000 feet that are being operated below 4,000 feet, the ignition timing should be retarded 7~ and engine idle reset. In addition, the MCU circuit jumper wire must be disconnected and taped to the MCU harness.


1. Move the carpeting away from the passenger front seat toeboard to expose the MCU harness.


2. Disconnect the jumper wire from the twoterminal connector in the MCU harness and tape the connector securely to the harness.


3. Retard ignition timing 7~ from the setting indicated on the original Vehicle Emission Control label in the engine compartment and reset engine idle speed to the setting indicated on this same label.


4. Install Vehicle Control Information Update label, P/N EF 8980 000 744, next to the original label.
These adjustments apply to 1985 Eagle/Jeep, 49-State/California/Canada 4.2L models with automatic transmission originally sold 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 MCU circuit jumper wire must be reconnected, the ignition timing and engine idle speed must be reset to original specifications and the Vehicle Emission Control Information Update label removed.


49-State/California/Canada 4.2L Engine Adjustment - Manual Transmission


On 1985 Eagle/Jeep, 49-State/California/ Canada 4.2L models with manual transmission originally sold for operation at altitudes below 4,000 feet that are being operated above 4,000 feet, the ignition timing must be advanced 7~, engine idle speed reset, and a jumper wire added to the MCU circuit. In addition, the idle/ decel switch must be connected to the carburetor EGR port instead of the spark port.


1. Move the carpeting away from the passenger front seat toeboard to expose the MCU harness.


2. Untape the two-terminal connector from the MCU harness.


3. Connect jumper wire, P/N 318 6890, to the two-terminal connector and reinstall the carpet.

Fig. 1 Modifying Low Altitude Model for High Altitude Operation:

4. Connect the idle/decel switch to the carburetor EGR port as follows (Fig. 1).
a. Disconnect vacuum line 1 from idle/decel switch and from tee connector 2 (Fig. 1). Place this line in the glove box - do not discard it.


b. Install cap, P/N 813 2325, over the open end of tee connector 2.


c. Cut and install tee connector, P/N 321 0891, in vacuum line 3 (Fig. 1). Position the connector about 1-1/4 inches from the EGRCTO end of the line.


d. Connect 75-inch long vacuum line 4 to the idle/decel switch and to the tee connector in line 3 (Fig. 1).


5. Advance ignition timing 7~ from the setting indicated on the original Vehicle Emission Control Information label in the engine compartment and reset engine idle speed to the setting indicated on the same label.


6. Install Vehicle Emission Control Information Update label, P/N EF 8980 000 743, next to the original label.


These adjustments apply to 1985 Eagle/Jeep, 49-State/California/Canada 4.2L models with manual transmission originally sold for use at altitudes below 4,000 feet. Refer to the original Vehicle Emission Control Information label to identify these vehicles.


NOTE: Whenever these vehicles are returned to operation at altitudes below 4,000 feet, the MCU jumper wire must be removed, the idle/decel switch reconnected to the carburetor spark port, the ignition timing and idle speed reset to original specifications, and the Vehicle Emission Control Update label removed.

Fig. 1 Modifying Low Altitude Model for High Altitude Operation:

Figure 1 Modifying Low Altitude Model for High Altitude Operation

On 1985 Eagle/Jeep, 49-State/California/ Canada 4.2L models with manual transmission originally sold for operation at altitudes above 4,000 feet that are being operated below 4,000 feet, the ignition timing must be retarded 7~, engine idle speed reset and the MCU jumper wire removed. In addition, the idle/decel switch must be connected to the carburetor spark port instead of the EGR port.


1. Move the carpeting away from the passenger front seat toeboard to expose the MCU harness.


2. Disconnect the jumper wire from the twoterminal connector in the MCU harness and tape the connector securely to the harness. Place the jumper wire in the glove box - do not discard it.

3. Reinstall the carpeting.

Fig. 2 Modifying High Altitude Model for Low Altitude Operation:

4. Connect the idle/decel switch to the carburetor spark port as follows (Fig. 2).


a. Cut and install tee connector, P/N 321 0891, in vacuum line 1 (Fig. 2). Position the connector about 1-1/4 inches from the spark port end of the line.


b. Disconnect vacuum line 2 from tee connector 3. Then reconnect line 2 to the tee connector just installed in vacuum line 1 (Fig. 2).


c. Plug open end of tee connector 3 with cap, P/N 813 2325.

Fig. 2 Modifying High Altitude Model for Low Altitude Operation:

Figure 2 Modifying High Altitude Model for Low Altitude Operation

5. Retard ignition timing 7~ from the setting specified on the original Vehicle Emission Control Information label and reset idle speed to the setting on the same label.


6. Install Vehicle Emission Control Information Update label, P/N EF 8980 000 744, next to the original label.


These adjustments apply to 1985 AMC/Jeep, 49-State/California/Canada 4.2L models with manual transmission originally sold for use at altitudes above 4,000 feet. Refer to the original Vehicle Emission Control Information label to identify these vehicles.

NOTE: Whenever these vehicles are returned to operation at altitudes above 4,000 feet, the MCU jumper wire must be reinstalled, the idle/decel switch reconnected to the EGR port, the ignition timing and idle speed reset and the Vehicle Emission Control Information Update label removed.