Exhaust Gas Recirculation: Description and Operation

CIVIC & CRX

Exc. 1986-87 Federal & High Altitude CRX HF

The vacuum signal is ported above the idle throttle valve position to eliminate EGR at idle. The EGR control solenoid valve A is designed to cut off the EGR flow. When the EGR control solenoid valve A is off and ported vacuum is introduced to the EGR valve and EGR control valve A, the EGR valve is opened, allowing exhaust gas into the intake manifold.
On all models except CRX 1500 HF except High Alt., with a cold engine, when the thermosensor B is on, EGR control solenoid valve A is energized and the EGR valve is closed for EGR flow cut off. When intake manifold vacuum rises during deceleration, the control switch is turned on to activate EGR control solenoid valve A and the EGR flow cut off.
On CRX 1500 HF High Alt. and Civic 1500 with manual transmission, the EGR control solenoid valve A is activated by the control unit.
On Civic 1300 and CRX 1500 HF, the EGR control solenoid valve B is designed to control EGR flow volume according to vehicle speed and engine load. When EGR control solenoid valve B is activated by the speed sensor and vacuum switch B, air volume flowing into the diaphragm chamber of EGR control valve increases and ported vacuum to the EGR valve is increased.
On Civic 1500 with auto. trans., Civic Wagon, and CRX 1500 HF, the EGR control solenoid valve C is designed to control the EGR flow volume according to driving conditions. When EGR control solenoid valve C is activated by the control unit, venturi vacuum is cut off, the ported vacuum is diluted with air and the EGR flow volume is increased.