Frequency Solenoid Valve "B"

The X-system consists of air control valve B, a feedback control solenoid valve, frequency solenoid valve B, and CV generator (CVG), a check valve, a vacuum chamber and silencer, as its components.
This system controls the air-fuel mixture ratio by controlling the opening of air control valve B according to the amount of vacuum at the diaphragm chamber of the valve.
The frequency solenoid valve is modulated by the control unit, and controls the amount of vacuum to air control valve B.
The CV generator proivides a stable vacuum level to the frequency solenoid valve.
This allows frequency solenoid valve B to more closely control the vacuum to air control valve B.
The accumulator and check valve also contribute to provide a stable vacuum for the control valve.
The vacuum chamber eliminates vacuum pulsation in the diaphragm chamber of air control valve B caused by the operation of frequency solenoid valve B.
The feedback control solenoid valve is provided to stop feedback operation at low engine speed such as idling.
Freqency solenoid valve B gets signals through the control unit from the oxygen sensor installed in the exhaust manifold. Air control valve B is opened only when the oxygen content is less than stoichiometric (rich air-fuel ratio).