Electronic Ignition Retard Test - Jeep 1987 Wrangler Workshop Manual

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ENGINES
iH8
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FUEL FEEDBACK SYSTEMS
DIAGNOSTIC TEST 5
ELECTRONIC IGNITION RETARD TEST
WARM ENGINE TO NORMAL OPERATING TEMPERATURE BEFORE PROCEEDING WITH
TEST.
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DISCONNECT VACUUM SWITCH ASSEMBLY WIRE CONNECTOR (MOUNTED ON
WHEELHOUSE). DISCONNECT AND PLUG THE VACUUM HOSE CONNECTED TO
THE DISTRIBUTOR. DISCONNECT THE ELECTRICAL CONNECTOR FROM THE
KNOCK SENSOR AND GROUND WIRE TO BLOCK WITH JUMPER WIRE. INCREASE
ENGINE RPM TO 1600 RPM AND CHECK IGNITION TIMING. ADJUST, IF
NECESSARY
S E E
I.S.
N
O
T
E
S
ALLOW ENGINE TO RETURN TO IDLE SPEED. CONNECT VACUUM SWITCH
ELECTRICAL CONNECTOR. INCREASE ENGINE SPEED TO 1 6 0 0 RPM. TIMING
SHOULD ADVANCE 6 °.
CHECK FOR VACUUM
SWITCH FAILURE. CHECK
FOR ELECTRICAL
CONTINUITY FROM
SWITCH TO MCU.
REPLACE MCU AND
RETEST.
NO
ALLOW ENGINE TO RETURN TO IDLE SPEED. CONNECT THE ELECTRICAL
CONNECTOR TO THE KNOCK SENSOR. INCREASE ENGINE RPM TO 1 6 0 0 RPM.
WHILE CHECKING TIMING, KNOCK ON THE INTAKE MANIFOLD NEXT TO THE
KNOCK SENSOR. THE TIMING SHOULD RETARD.
CHECK FOR ELECTRICAL
CONTINUITY OF KNOCK SENSOR
HARNESS CONNECTOR TO
PIN 51 OF MCU CONNECTOR.
REPLACE KNOCK SENSOR.
RETEST.
NO
YES
ALLOW ENGINE TO RETURN TO IDLE SPEED.
THE DISTRIBUTOR.
CONNECT THE VACUUM HOSE TO
TEST COMPLETE.
83085H(J)
B-281