Auxiliary Air Valve System: 4A-FE

With engine coolant less than 176°F (80°C), install tachometer. See ADJUSTMENTS article in this section for tachometer attaching points.
Remove air cleaner. Start engine. Place finger over air valve port to block airflow. See Fig 1. Engine speed should drop noticeably.
Warm engine to normal operating temperature. Place finger over air valve port to block airflow. Engine speed should not drop more than 50 RPM.
If engine RPM does not respond as indicated, check for vacuum leaks after the valve or restricted chamber in auxiliary air valve circuit. If no defects are found, replace auxiliary air valve.

Fig 1: Identifying Auxiliary Air Valve