Exhaust Gas Recirculation: Description and Operation

Operation:

The Exhaust Gas Recirculation (EGR) system is used to lower Oxides of Nitrogen (NOx) emission levels caused by high combustion temperature. It does this by decreasing combustion temperature.

The main element of the system is the linear EGR valve. The EGR valve feeds small amounts of exhaust gas back into the combustion chamber. With the fuel/air mixture thus diluted, combustion temperatures are reduced.

The PCM monitors EGR actual position and adjusts pintle position accordingly. The PCM uses information from the following sensors to control the pintle position:
^ Engine Coolant Temperature (ECT) sensor.
^ Throttle Position (TP) sensor.
^ Mass Air Flow (MAF).