Computers and Control Systems: Adjustments

NOTE: Incorrect ignition timing can cause idle speed changes. Conversely, incorrect idle speed can affect the ignition timing. Ignition timing and idle speed should be adjusted concurrently.

CURB IDLE SPEED
1. 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. See Adjustment Procedures.

Engine Idle Speed Inspection:

3. Insert a paper clip into the CRC filter connector as shown. This will allow the use of an external tachometer.

4. Start the engine and operate at 2500 rpm for more than 5 seconds and then at idle for 2 minutes.
5. Check the engine idle speed. If it is NOT within specifications, check the idle speed control system.

Curb Idle Speed:
700 ± 100 RPM

6. Stop engine and disconnect tachometer (if further adjustments are required, do not disconnect the meter).

Accelerator Cable Adjustment Bolts:

IDLE SPEED CONTROL (ISC) SYSTEM
1. Loosen the accelerator cable, so a slight amount of slack is present.
2. Turn the ignition switch to the ON position.
3. Wait at least 15 seconds and check the idle speed control plunger position. The plunger should extend to a fast idle position, then fully retract after 15 seconds. This is the initial position.

ISC Servo, Idle Position Switch, MPS Location:

4. Disconnect the connector of the idle speed control servo.
5. Turn the ignition switch OFF and disconnect the electrical connector for the idle speed control servo. This will lock the idle speed control plunger at the initial position.

Idle Speed Adjusting Screws:

6. Loosen the fixed speed adjusting screw (SAS) fully.
7. .Start the engine and check that the idle speed is within specifications.

Idle Speed:
700 ± 50 RPM

8. If idle speed is not as specified, adjust the idle speed control adjusting screw.
9. Turn the fixed speed adjusting screw (SAS) in until the engine speed rises slightly.
10. Back-off the SAS to the "touch point", where the engine speed ceases to decrease.
11. Back-off the SAS an additional half turn from the "touch point".
12. Stop the engine. Readjust the accelerator cable.
13. Reconnect the electrical connector for the idle speed control servo.
14. 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.
15. Reconnect the battery, start the engine and check the idle speed.

Idle Speed:
700 ± 50 RPM