Engine - Idle Speed Adjustment Procedures
89AMCjeep03Models
1987-1989 YJ Body With 4.2L Engine
Subject
Engine Idle Speed Adjustment Procedures
Index
DRIVEABILITY
Date
April 10, 1989
No.
18-52-89
P-1421 (C18-08-9)
BODY CODE LEGEND
YJ - WRANGLER
SYMPTOM/CONDITION
Following are the proper procedures for engine idle speed adjustment on 1987-1989 Wrangler vehicles equipped with a 4.2L engine.
REPAIR PROCEDURE
NOTE: THE ENGINE ADJUSTMENT PROCEDURES MUST BE PERFORMED WITH THE ENGINE AT NORMAL OPERATING TEMPERATURES AND ALL ELECTRICAL ACCESSORY SWITCHES IN THE OFF POSITION.
THE ADJUSTMENTS MUST BE PERFORMED IN THE FOLLOWING ORDER:
1. IGNITION TIMING
2. CURB IDLE SPEED
3. FAST IDLE SPEED
4. SOLE-VAC THROTTLE POSITIONER
FIGURE 1:
IGNITION TIMING
1. Remove the air filter/cleaner assembly.
2. Set the vehicle parking brake. Place automatic transmissions in the PARK position and manual transmissions in NEUTRAL.
3. With the ignition switch OFF, connect an ignition timing light to the Number 1 spark plug and a tachometer to the coil negative terminal (A). Figure 1.
FIGURE 2:
4. Disconnect the 4" and 10" Hg vacuum switch assembly wire connector. The vacuum switch assembly is mounted to the bulkhead.
5. Disconnect and plug the distributor vacuum advance hose (C). Figure 2.
6. Start the engine. Increase the engine speed to 1600 rpm and check the ignition timing. If necessary, adjust the timing to the specification listed on the underhood Emission Control Information Label.
7. Tighten the distributor hold-down clamp and verify that the ignition timing is correct.
8. Turn the ignition switch OFF and remove the timing light.
9. Connect the hose to the distributor vacuum advance mechanism. Connect the wire connector to the 4" and 10" vacuum switch assembly.
FIGURE 3:
FIGURE 4:
FAST IDLE SPEED
1. Disconnect and plug the EGR valve vacuum hose (D). Figure 3.
2. Set the parking brake. Place automatic transmissions in the PARK position and manual transmissions in NEUTRAL.
3. Start the engine.
4. Position the fast idle speed adjustment screw (E) against the shoulder of the second step (F) of the fast idle cam. Figure 4.
5. Refer to the underhood Vehicle Emission Control Information Label and adjust the fast idle speed to the specified rpm. Adjust by turning the fast idle speed adjustment screw (E). Figure 4.
6. Manually open the throttle momentarily to allow the fast idle cam to return to its normal curb idle position.
7. Turn the ignition switch OFF. Remove the plug and connect the vacuum hose to the EGR valve.
FIGURE 5:
FIGURE 6:
CURB IDLE SPEED AND SOLE-VAC THROTTLE POSITIONER
1. Disconnect the vacuum hose (G) from the Sole-Vac vacuum actuator and plug it. Figure 5.
2. Disconnect the Sole-Vac holding solenoid wire connector (H). Figure 6.
FIGURE 7:
FIGURE 8:
3. Firmly set the parking brake. Start the engine. Place manual transmissions in NEUTRAL and automatic transmissions in DRIVE.
4. Increase the engine speed to above 1200 rpm for 3 to 5 seconds and allow engine to return to curb idle speed.
5. Refer to the underhood Vehicle Emission Control Information Label and adjust the carburetor curb (slow) idle speed adjustment screw (J) to obtain the specified curb (slow) idle speed rpm. Figure 7.
6. Apply a direct source of 10-15" Hg of vacuum to the vacuum actuator (K), using a hand operated vacuum pump or equivalent. Figure 8.
FIGURE 9:
7. Increase the engine speed to above 1200 rpm for 3 to 5 seconds and allow the engine to return to its curb idle position.
8. Refer to the Vehicle Emission Control Information Label and with the Sole-Vac throttle positioner fully extended, turn the vacuum actuator adjustment screw (L) on the throttle lever until the specified engine rpm is obtained. Figure 9.
9. Disconnect the vacuum source from the vacuum actuator.
10. With a jumper wire, apply battery voltage (12V) to energize the holding solenoid.
11. Hold the throttle open manually to allow the throttle positioner to fully extend.
NOTE: THE THROTTLE MUST BE OPENED MANUALLY TO ALLOW SOLE-VAC THROTTLE POSITIONER TO BE FULLY EXTENDED.
FIGURE 10:
12. Refer to the Vehicle Emission Control Information Label and adjust the Sole-Vac throttle positioner (M) to obtain the specified engine rpm. Figure 10.
13. Verify that the adjustments made to the curb idle and the Sole-Vac (vacuum and electric) have not changed.
14. Turn the ignition switch OFF.
15. Remove the jumper wire from the Sole-Vac holding solenoid wire connector. Reconnect the Sole-Van holding solenoid wire connector.
16. Remove the plug and connect the vacuum hose to the vacuum actuator.
17. Disconnect the tachometer. Install the air filter/cleaner assembly.
18. Road test the vehicle.
POLICY: Reimbursable within the provisions of the warranty
TIME ALLOWANCE:
Labor Operation No. 14-30-07-90 . . . . . . . . . . 0.6 Hrs.
FAILURE CODE: RO - Driveability
REAR WHEEL DRIVE LABOR OPERATION TIME SCHEDULE