X System

Exc. 1987-88 Accord
The X-system consists of air control valve B, frequency solenoid valve B, constant vacuum valve on 1985-87 Prelude, check valves, surge tanks A and B, feedback control solenoid valve on 1985-86 Accord, Civic 1500 and CRX, and the control unit. When frequency solenoid valve B is opened by the control unit, manifold vacuum is applied to air control valve B. When valve B opens, it allows correct amount of air to be fed into the intake manifold. Surge tank A and check valves act as a vacuum reservoir, while surge tank B dampens the vacuum pulses so that steady vacuum is applied to air control valve B. The feedback control solenoid valve is provided to stop feedback operation under low engine speed and cold engine temperature.