Idle Speed: Testing and Inspection

1. With vehicle on PARK (A/T) or NEUTRAL (M/T), START the engine and allow it to warm up until the cooling fan cycles at least once, then shut OFF engine.
2. Connect a timing light and tachometer to the engine.
3. Disconnect the coolant temperature sensor and START the engine. Adjust basic timing to 12° BTDC +/- 2°, then shut OFF the engine and reconnect the coolant temperature sensor.
4. Disconnect the 3/16" manifold vacuum purge line from the top of the throttle body and cap the throttle body nipple.
5. Connect the scan tool to the engine compartment diagnostic connector. START the engine and allow it to idle for at least one minute.
6. Using the scan tool, access "Minimum Airflow Idle Speed". When this mode is entered, the following will occur:
a. Automatic Idle Air Speed (AIS) motor will fully close.
b. Idle spark advance will become fixed.
c. The engine rpm will be displayed on the scan tool.
7. Check the idle rpm with a tachometer. If the idle rpm is within 600-1050 rpm, the throttle body minimum air flow is correct. If it is not, clean or replace the throttle body. Throttle Body Replacement
8. Shut OFF the engine; remove the scan tool, tachometer, and timing light; reconnect the purge line to the throttle body, and clear any fault codes that may have been set.