Civic L4-1590cc 1.6L SOHC (VTEC) (1992)
Fast Idle Valve: Description and Operation
Fast Idle Valve
The Fast Idle Valve, mounted on the throttle body next to the throttle angle (TPS) sensor, raises the idle speed when the engine is cold. The Fast Idle
Valve is controlled by a thermowax plunger type valve. When the engine coolant is cold, the thermowax contracts the plunger which opens the valve
allowing air to bypass the throttle plate and idle adjusting screw into the intake manifold. When the engine coolant warms up, the valve closes and the
bypass air flow is blocked.