Base Idle Speed Adjustment

IDLE SPEED INSPECTION

NOTE:
a. Adjustment of the idle speed is usually unnecessary. Idle speed on fuel injected vehicles is controlled by the MPI Control Module through the Idle Speed Control Servo.

b. NEW FOR 1991: On Canadian model vehicles, the head lights, tail lights remain lit even after the headlight switch has been turned off. This is caused by the Daytime Running Light circuit, and does not indicate a problem.

Before starting the Inspection or Adjustment Procedures, be sure:

- Engine coolant temperature has reached 80-95~C (176-205~F)
- Lights, engine cooling fan, and electrical accessories are OFF
- Transaxle is in NEUTRAL or PARK
- Steering wheel is at a center position (power steering equipped vehicles)
- Parking brake is applied.
- Verify the ignition timing is set to 15~ BTDC @ 700 +/- 100 RPM.

CAUTION: Improper setting of the throttle valve opening will increase exhaust gas temperatures at deceleration, which will greatly reduce the life of the Catalytic Converter. Also, fuel consumption and engine braking will be affected.

Tachometer Connection Using A Paper Clip:

1. Insert a paper clip into the 3-pin connector from the harness side of the connector. Do NOT disconnect the connector.

2. Connect a primary-voltage-detecting tachometer to the paper clip.
NOTE: The tachometer should indicate 1/3 of the actual engine speed. Multiply the tachometer reading by 3 for the actual engine speed.

Self-Diagnostic Connector Grounded (under dash drivers side):

3. Using a jumper wire, ground the # 10 terminal of the Self-Diagnosis connector.

Ignition Timing Adjustment Terminal Grounded:

4. Using a second jumper wire, ground the Ignition Timing Adjustment Terminal, located in the engine compartment.

5. Start and run the engine for more than 5 seconds at 2,000 to 3,000 rpm.

6. Reduce the engine rpm to idle and check the Basic Idle Speed. 5~ +/- 2~ BTDC @ 700 +/- 50 RPM
If the idle speed is within specifications, proceed to step # 7.

NOTE: If the idle speed does not meet specifications, check the following before adjusting the Basic Idle Speed.

a. If the engine is stalling or the idle speed is below specifications, check for deposits stuck to the back of the throttle valve.
If so, refer to REPLACEMENT AND REPAIR PROCEDURES/THROTTLE VALVE.

b. If the engine idle speed is higher than specifications and the speed adjusting screw is fully closed. Then, check for indications that the Fixed Idle Speed Adjusting Screw has been altered. If so, proceed to FIXED SPEED ADJUSTMENT SCREW procedures.

c. If there is no indication, it is possible that there is leakage resulting from the deterioration of the Fast Idle Air Valve (FIAV). The throttle body will need to be replaced.

Adjusting The Idle Speed:

If none of the above conditions apply, then turn the speed adjusting screw until the engine is running at 700 +/- 50 RPM.

7. Turn OFF the engine.

8. Disconnect the grounding jumper wire from the diagnosis connector.

9. Disconnect the grounding wire form the Ignition Timing Adjustment Terminal and reinstall the waterproof connector.

10. Start the engine and let it idle for about 10 minutes. Verify that the engine idle is smooth and has returned to the Curb Idle Speed. 700 +/- 100 RPM

11. Disconnect and remove the tachometer.