Two-Port EGR System (Non-Turbo)

Routing of TWO-PORT EGR system is similar to the ON-OFF EGR system except that orifice is not used. Amount of recirculated exhaust gas is controlled by a variable opening in the EGR valve.

Opening of EGR valve is regulated by 2 adjacent vacuum ports in throttle valve housing. At idle, vacuum is not applied to either port, resulting in a closed system.

At off-idle or low speed, vacuum is applied to one port only, allowing partial opening of EGR valve. When throttle valve opens past the second port, full vacuum is applied to both ports. This allows full gas circulation through EGR valve. Thermostatic valve prevents EGR operation when engine temperature is below 110°F (43°C).