General System Description

Fig. 1 Feedback Control System.:

Fig. 2 Feedback Control System.:

Fig. 3 Feedback Control System.:

Fig. 4 Feedback Control System.:

Fig. 5 Feedback Control System.:

Fig. 6 Feedback Control System.:

Fig. 7 Feedback Control System.:

Fig. 8 Feedback Control System.:

Fig. 9 Feedback Control System.:

The feedback control system, Figs. 1 through 9 maintains proper air/fuel mixture ratio by allowing air into the intake manifold, to correct rich fuel condition. An electronic control unit monitors oxygen sensor signals, and signals from a variety of other sensors, in order to determine the ideal air/fuel mixture for engine operating conditions. The control unit then operates a group of solenoid valves that control vacuum applied to air control valves. The air control valves, in turn, control the amount of additional air supplied to the intake manifold.
The system used on 1986-87 CRX HF models (Federal and high altitude) consists solely of the control unit and a frequency solenoid valve that controls air flow. The frequency solenoid valve is pulsed by the control unit a fixed number of times per second, with the amount of air transmitted being controlled by the duration of each pulse.
The feedback control system used on all other models consists of a group of sub-systems. The sub-systems include: the X-system, the M-system, and on 1987 Prelude and 1987-88 Accord, an idle feedback control system.