Exhaust Gas Recirculation: Description and Operation

Description




The EGR system is designed to reduce oxides of nitrogen emissions (NOx) by recirculating exhaust gas through the EGR valve and the intake manifold into the combustion chambers. It is composed of the EGR valve, ECM/PCM and various sensors.

The ECM/PCM contains memories for ideal EGR valve lifts for varying operating conditions. The EGR valve lift sensor detects the amount of EGR valve lift and sends it to the ECM/PCM. The ECM/PCM then compares it with the ideal lift in its memory (based on signals sent from the other sensors). If there is any difference between the two, the ECM/PCM controls current to the EGR valve lift.