Without Scan Tool

The engine idle speed is controlled by the powertrain control module (PCM) through the idle air control (IAC) valve. The IAC value opens and closes the idle air (bypass) passage in the throttle body according to signals from the PCM. The PCM determines the correct engine idle speed by using information from various sensors and switches. The PCM increases IAC duty (increases the opening in the idle air passage) when engine speed drops below a specified value. The PCM maintains a smooth and stable 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 correct free-play.
^ Inspect the lead wires and the hoses of the sequential multiport fuel injection (SFI) and the [1][2]EVAP control systems for secure connections.
^ Turn OFF all accessories (A/C, wipers, heater, lights, etc.).
^ Make sure that the air cleaner (ACL) is installed correctly.
^ Check the air induction system for restrictions.
^ Check the vacuum hoses for correct routing. Refer to the Emission Label.
^ Check for vacuum leaks and repair as necessary.

Important: Before starting the engine, place the manual selector in P (automatic transaxle) or place the gearshift control lever in neutral (manual transaxle). 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 (5) located next to the PCM (7) behind the glove box.
6. Connect a fused jumper wire to terminal 2 (diagnostic switch) and terminal 4 (ground) of the duty check data link connector.
7. Connect a DMM to terminal 6 (duty check) and terminal 4 (ground) of the duty check data link connector.
8. Select DC voltage and duty cycle (Hz) or dwell on the DMM.
9. Monitor the readings on the tachometer and the DMM while turning ON the A/C.
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 is turned ON, refer to A/C Idle Circuit Diagnosis. Component Tests and General Diagnostics
^ Check the A/C valve and IAC circuit for faults if the indicated A/C duty cycle is not within the specified valve. Repair as necessary.