Exhaust Gas RECIRCULATION: Description
The Exhaust Gas Recirculation (EGR) system is used to reduce NOx emissions by recycling metered amounts of exhaust gas back into the intake/combustion system. On 1974-75 models, system consists of an exhaust gas filter, a vacuum controlled EGR valve, and connecting hoses.
On 1976-77 Fox, a single stage EGR valve is used. The EGR valve operates off of venturi vacuum via vacuum booster and engine coolant (thermal) temperature control valve.
On 1978-79 models, exhaust gas recirculation is accomplished through a vacuum-controlled EGR valve which responds to a vacuum signal from the throttle housing. This signal is determined by the position of the throttle plate. System consists of an EGR valve, temperature control valve, vacuum amplifier, vacuum delay valve (auto, trans, only) and a vacuum reservoir.