Engine - Idle Speed Low/Inconsistent
87AMCjeep914E458
NOVEMBER 1987
1981-87 GRAND WAGONEER/ TRUCK VEHICLES WITH 4.2L ENGINE
ENGINE Attention: Workshop, Parts Department
THIS I.S. NOTE HAS BEEN REVISED AS INDICATED BY THE REVISION BARS:
IDLE SPEED
The idle speed may be low, or inconsistent on some 1981-87 Grand Wagoneer/Truck vehicles equipped with a 4.2L engine. If this condition exists, the following items must be adjusted to obtain proper engine operation.
^ IGNITION TIMING
^ CURB IDLE SPEED
^ FAST IDLE SPEED
^ SOLE-VAC THROTTLE POSITIONER
Refer to the adjustment procedures listed below.
ADJUSTMENT PROCEDURES
The engine must be at normal operating temperature and all electrical accessory switches in the OFF position.
Ignition Timing
1. Remove the air filter assembly.
2. Set the parking brake. Shift automatic transmissions to PARK and manual transmissions to the NEUTRAL position.
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).
Six-Cylinder Firing Order
4. Disconnect the 4-in. and 10-in. Hg vacuum switch assembly wire connector (located adjacent to the vacuum switch assembly).
5. Disconnect and plug the distributor vacuum advance hose (C).
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 Emission Control Information label.
Tighten the distributor hold-down clamp and verify that the ignition timing is correct.
Turn the ignition switch OFF and remove the timing light.
Connect the hose to the distributor vacuum advance mechanism. Connect the wire connector to the vacuum switch assembly.
Fast Idle Speed
1. Disconnect and plug the EGR valve vacuum hose (D).
2. 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) in contact with and against the shoulder of the second step (F) of the fast idle cam.
5. Refer to the Vehicle Emission Control Information label located under the hood. Adjust the fast idle speed to the correct rpm. Adjust by turning the fast idle speed adjustment screw (E).
6. Remove the fast idle speed adjustment screw from the fast idle cam and allow the engine to return to curb idle speed.
7. Turn the ignition switch OFF
8. Remove the plug and connect the vacuum hose to the EGR valve.
Curb Idle Speed and Sole-Vac Throttle Positioner
1. Disconnect the vacuum hose (G) from the Sole-Vac vacuum actuator and plug it.
2. Disconnect the Sole-Vac holding solenoid wire connector (H).
3. Start the engine.
4. Place manual transmissions in NEUTRAL and automatic transmissions in DRIVE. Set the parking brake firmly.
5. Increase the engine speed to above 1200 rpm for 3 to 5 seconds and allow the engine to return to curb idle speed.
6. Adjust the carburetor curb (slow) idle speed adjustment screw (J) to obtain the specified curb (slow) idle speed rpm. Refer to the Vehicle Emission Control Information label.
7. Apply a direct source of 34-51 kPa (10-15 in. Hg) vacuum to the vacuum actuator (K). Use Hand Operated Vacuum Pump Tool J-23738-A, or equivalent.
8. Increase the engine speed to above 1200 rpm for 3 to 5 seconds and allow the engine to return to curb idle speed.
9. 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. Refer to the Vehicle Emission Control Information label.
10. Disconnect the vacuum source from the vacuum actuator.
11. With a jumper wire, apply battery voltage (12V) (or connect the holding solenoid wire connector and turn ON the air conditioner with the compressor clutch wire connector disconnected) to energize the holding solenoid.
12. Hold the throttle open manually to allow the throttle positioner to fully extend.
NOTE: Without the vacuum actuator, the throttle must be opened manually to allow the Sol-Vac throttle positioner to be fully extended.
13. Adjust the Sole-Vac throttle positioner (M) to obtain the specified engine rpm. Refer to the Vehicle Emission Control Information label.
14. Turn the ignition switch OFF.
15. Remove the jumper wire from the Sole-Vac holding solenoid wire connector (if connected).
16. Connect the Sole-Vac holding solenoid wire connector.
17. Remove the plug and connect the vacuum hose to the vacuum actuator.
18. Disconnect the tachometer.
19. If disconnected, connect the A/C compressor clutch wire connector.
20. Install the air filter assembly.
21. Road test the vehicle.
SRT/TIC INFORMATION
OPERATION DESCRIPTION NUMBER TIME TIC
CO. IDLE SPEED, ENGINE-ADJUST 0106 0.6 1-265
INC. IGNITION TIMING, FAST IDLE, CURB IDLE AND SOLE-VAC THROTTLE POSITIONER ADJUSTMENTS
FILING INSTRUCTIONS
Record this I.S. Note on page B-38 of the M.R. 253 manual and file it in the manual.