Jeep 1987 Wrangler Workshop Manual page 1160

On 1986 Grand Wagoneer/Truck, 49-State/
California/Canada 5.9L models originally sold
for operation at altitudes above 4,000 feet that
are being operated below 4,000 feet, the ignition
timing a s s h o w n on the original V e h i c l e
Emission Control Information label in the engine
compartment should be retarded 7 ° and engine
idle reset to the specification indicated on this
s a m e label.
1. 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 s a m e label.
2. Install Vehicle Emission Control Information
Update label, part number E F 8980 000 819,
next to the original label.
T h e s e a d j u s t m e n t s apply to 1 9 8 6 G r a n d
Wagoneer/Truck, 49-State/California/Canada
5.9L models 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 ignition timing and engine idle
s p e e d m u s t b e r e s e t to o r i g i n a l
specifications and the Vehicle Emission
C o n t r o l I n f o r m a t i o n U p d a t e l a b e l
removed.
EGR-CTO
1. SPARK PORT-TO-CANISTER PURGE SIGNAL VACUUM
LINE (INSTALL TEE CONNECTOR 3210891 IN THIS LINE
ABOUT 1-1/4 INCH FROM SPARK PORT END OF LINE).
2. IDLE/DECEL SWITCH TO-EGR PORT VACUUM LINE
(DISCONNECT FROM TEE CONNECTOR 3 AND
RECONNECT TO TEE CONNECTOR JUST INSTALLED
IN LINE 1).
3. EGR PORT TOEGR-CTO VACUUM LINE TEE
CONNECTOR (PLUG OPEN END WITH CAP 8132325
AFTER DISCONNECTING HOSE 2).
4. CARBURETOR EGR PORT (E).
5. CARBURETOR SPARK PORT(S).
IDLE/DECEL SWITCH
Fig. 2 Modifying High Altitude Model for Low Altitude Operation