Ported & Integral BACKPRESSURE Systems

Both systems are controlled by an EGR valve. When valve is open, exhaust gas enters manifold passages. When closed, no exhaust gas is allowed to enter intake manifold. Vacuum signals control opening and closing of EGR valve.

Some light duty emission systems use a backpressure transducer to aid in controlling exhaust gas recirculation. This unit senses exhaust gas backpressure and modulates vacuum signal to EGR valve in response to amount of backpressure. Backpressure is used to provide information on engine operation modes. Backpressure transducer is integral with EGR valve.

Fig 1: Cutaway View of EGR Valve Without Backpressure Transducer When testing, apply 8 in. Hg vacuum to EGR valve and hold it for at least 30 seconds.