Computers and Control Systems: Adjustments

NOTE: Adjustment of idle speed is usually not required.

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).
e. Ignition timing verified correct.

Tachometer Lead Connector Location:

2. Insert a paper clip in the idle speed connector (blue).

Tachometer Installed:

3. Connect a tachometer to the engine speed detection terminal.
NOTE: The tachometer should read at 1/3 of the actual engine speed. Multiply the reading by 3 to obtain the correct RPM.

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:
700 ± 100 RPM

7. Stop engine and disconnect tachometer. (Leave tachometer connected, if further adjustments are required).


IDLE SPEED CONTROL (ISC) SYSTEM
1. Start the engine and warm to operating temperature, then turn the engine off.

Tachometer Lead Connector Location:

2. Insert a paper clip in the idle speed connector (blue).

Tachometer Installed:

3. Connect a tachometer to the inserted paper clip.
NOTE: The tachometer should read at 1/3 of the actual engine speed. Multiply the reading by 3 to obtain the correct RPM.

Data Transmission Selector Terminal Identification:

4. Use a jumper wire, ground the self diagnosis/data transfer switching terminal (terminal 10) of the diagnostic connector (white). The connector is located inside the passenger compartment, under the dash, adjacent to the left kick panel.

Ignition Timing Adjustment Terminal Location:

5. With the ignition OFF, remove the waterproof plug from the connector (brown) for ignition timing adjustment and ground the terminal using a jumper wire.
6. Start the engine and allow it to run at curb idle speed.
7. Verify Idle Speed.

Curb Idle Speed
700 ± 100 rpm.

Idle Speed Adjustment Location:

8. If the idle speed is NOT as specified, adjust the speed adjusting screw.
9. Stop the engine, disconnect jumper wires, remove tachometer and reinstall waterproof plug in the connector for ignition timing adjustment.
10. 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.
11. Reconnect the battery, start the engine and check that the engine is operating in the normal idle range.