Without Scan Tool

The engine idle speed is controlled by the Powertrain Control Module (PCM) through the Idle Air Control (IAC) valve. The IAC valve opens and closes the idle air passage in the throttle body according to signals from the PCM. The PCM uses various information from sensors and from switches in order to determine the correct engine idle speed. The PCM increases the opening in the idle air passage when the engine speed drops below a specified value. The PCM maintains a smooth idle by monitoring certain engine components in order to respond to changes in engine load. The engine idle speed is a factory set calibration and is not adjustable.
1. Perform all of the following checks and operations:
^ Check the accelerator cable for free movement and for correct free-play. Refer to Accelerator Cable Adjustment.
^ Inspect the lead wires and the hoses of the sequential multiport fuel injection (SFI) and of the EVAP control systems for secure connections.
^ Turn off all of the accessories.
^ Verify that the air cleaner is installed correctly.
^ Check the air induction system for restrictions.
^ Check the vacuum hoses for correct routing. Refer to the Emission Label.
^ Check for and repair any vacuum leaks as necessary.

IMPORTANT: Before starting the engine, place the automatic transaxle selector in Park, or place the manual transaxle control lever in neutral. Set the parking brake, and block the drive wheels.

2. Start the engine.
3. Run the engine to normal operating temperatures.
4. Connect a tachometer to the vehicle.




5. Access the duty check data link connector (8) that is located next to the PCM (7) behind the glove box.




6. Connect a fused jumper wire to the terminal 2 diagnostic switch and the terminal 4 ground of the connector.
7. Connect a DMM to the duty check terminal 6 and to the ground terminal 4 of the connector.
8. Select the DC voltage and the duty cycle (Hz) or dwell settings on the DMM.
9. Monitor the readings on the tachometer and on the DMM while turning ON the A/C.

Idle Speed/IAC Duty Values:

10. Compare the observed engine speed and the observed IAC duty cycle with the values specified in the table.
^ If the indicated idle speed is not within the specified value, refer to Rough, Unstable, or Incorrect Idle and Stalling. Rough, Unstable, or Incorrect Idle and Stalling
^ If the idle speed does not increase to the specified value when the A/C turns ON, refer to A/C Idle Circuit Diagnosis. Component Tests and General Diagnostics
^ Check the IAC valve and the IAC circuit for faults if the indicated IAC duty cycle is not within the specified value. Repair as necessary.