Computers and Control Systems: Adjustments
CURB IDLE SPEED1. Confirm initial inspection conditions:
a. Engine coolant temperature is 185 - 205°F.
b. Lights, cooling fan and all accessories are OFF.
c. Transaxle is in neutral or park.
d. Steering wheel is in straight-ahead position, (on vehicles with power steering).
2. Check the ignition timing and adjust, if necessary. (Refer to procedure)
Connecting Tachometer:
3. Connect a tachometer to the engine speed detection terminal.
4. Maintain engine speed at 2,000 - 3,000 RPM for 5 - 10 seconds.
5. Allow engine to idle for 2 minutes.
6. Check the engine idle speed. If it is NOT within specifications, check the idle speed control system.
Curb Idle Speed:
750 ± 100 RPM
7. Stop engine and disconnect tachometer. (Leave tachometer connected, if further adjustments are required).
Fig. 74 Loosening Accelerator Cable:
IDLE SPEED CONTROL (ISC) SYSTEM
1. Loosen the accelerator cable, so a slight amount of slack is present. Fig. 74
2. Turn the ignition switch ON, but DO NOT start the engine.
3. Wait at least 15 seconds and check the idle speed control plunger position. The voltmeter should register 0.9 volt. This is the initial position.
Idle Speed Control Servo Connector:
4. Turn the ignition switch OFF and disconnect the electrical connectors for the idle speed control servo. This will lock the idle speed control plunger at the initial position.
5. Open the throttle valve more than half-way, two or three times. Release the throttle valve and let it return with a click.
Idle Speed Adjustment Screws:
6. Loosen the fixed speed adjusting screw fully.
7. Connect a tachometer, start the engine and maintain idle speed.
8. Check that the idle speed is within specifications.
Basic Idle Speed:
750 ± 50 RPM
9. If idle speed is not as specified, adjust the idle speed control adjusting screw with a hexagon wrench.
10. Turn the fixed speed adjusting screw in until the engine speed rises slightly.
11. Back-off the fixed speed adjusting screw to the "touch point", where the engine speed ceases to decrease.
12. Back-off the fixed speed adjusting screw an additional half turn from the "touch point".
13. Stop the engine. Readjust the accelerator cable.
14. Reconnect the electrical connector for the idle speed control servo and remove the voltmeter from the engine.
15. With the ignition switch OFF, disconnect the negative battery terminal for at least 15 seconds. This will clear any diagnostic codes that may have occurred during testing.
16. Reconnect the battery, start the engine and check that the engine is operating in the normal idle range.