Fast Idle Valve: Notes
WARNING: This page is about a different car, the 1992 Acura NSX and 1991 Acura NSX. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
The fast idle valve is factory adjusted and should not be disassembled.
To prevent erratic running when the engine is warming up, it is necessary to raise the idle speed. The fast idle air bypass valve is controlled by a thermowax plunger. When the engine is cold, the engine coolant surrounding the thermowax contracts the plunger, allowing additional air to be bypassed into the intake manifold so that the engine idles faster. When the engine reaches operating temperature, the valve closes, reducing the amount of air bypassing into the manifold.