Idle Speed Adjustment

IDLE SPEED/ISC DUTY ADJUSTMENT (INCLUDING A/C VSV ADJUSTMENT)

Before idle speed check and adjustment, make sure of the following:
- Lead wires and hoses of Electronic Fuel Injection and engine emission control systems are connected securely.
- Accelerator cable has some play, that is, it is not tight.
- Valve lash is checked and adjusted according to maintenance schedule.
- Ignition timing is within specification.
- All accessories (wipers, heater, lights, A/C etc.) are out of service.
- Air cleaner has been properly installed and is in good condition.

After above items are all confirmed, check idle speed and ISC duty as follows.


NOTE: Before starting engine, place transmission gear shift lever in "Neutral", and set parking brake and block drive wheels.


1. Warm up engine to normal operating temperature.

Grounding Diagnostic Switch Terminal:

2. Connect jumper wire between "DIAGNOSIS SWITCH TERMINAL" in monitor coupler (near left shock tower) and ground and make sure that "CHECK ENGINE" light indicates diagnostic code No. 12. If code 12 does not flash, refer to Powertrain Management/Computers and Control Systems/Testing and Inspection/Procedures.

Connecting Duty Meter:

3. Stop engine and connect duty meter between duty check terminal and ground terminal of monitor connector.
4. Turn ON ignition switch and wait for 5 seconds. Then restart engine and run it at 2,000 rpm for 5 minutes to warm it up completely and let it slow down to idle speed.

Idle Speed And ISC Duty (With Duty Meter):

Idle Speed Adjusting Screw:

5. Check ISC duty and idle speed. If duty and/or idle speed is out of specifications, adjust it by turning idle speed adjusting screw.

Engine idle speed 850 ± 50 rpm
ISC duty at specified idle speed 35%

ISC Duty As Compared With Expected Voltage:

NOTE: Refer to the above chart for duty readings in relation to an analog voltmeter.


6. Upon completion of adjustment, install adjusting screw cap to throttle body.
7. This step is for checking and/or adjusting engine idle speed and ISC duty when A/C is working.

With vehicles without A/C, advance to step 8. With A/C equipped ones, follow procedure described below.

Idle/Duty Specification With A/C:

IMPORTANT SERVICE SPECIFICATION
Specified values for idle speed vary depending on types of ECM. Refer to the above chart for ECM identification and idle speed specification. Types of ECM can be identified with last number of ECM P/N.

a) Turn A/C switch ON and set heater blower switch to low speed position.
b) Check to ensure that ISC duty and idle speed are within specification.

A/C Idle Speed Adjusting Screw:

c) If it is not within specified range, adjust it by turning adjusting screw of A/C VSV.

8. Upon completion of adjustment, disconnect service wire from monitor connector and install cap.
9. Check that A/C idle speed is correct with Diagnostic Terminal ungrounded.

A/C engine idle speed 900 ± 50 rpm