Fast Idle Air (FIA) Valve

Fast Idle Air (FIA) valve is located on intake manifold. Air valve is used to increase idle speed (airflow) when engine is started at a low ambient temperature. FIA valve consists of a thermowax pellet, spring and plunger. Water from cooling system passes through valve, directly across thermowax pellet.

When coolant temperature is low, thermowax pellet is contracted, allowing air to pass under end of plunger and into intake manifold. This air by-passes throttle plate, increasing idle speed for improved cold engine driveability. As coolant temperature increases, thermowax pellet expands, gradually blocking off by-passed air and decreasing idle speed.