Exhaust Gas Recirculation: Description and Operation

Description
- The Exhaust Gas Recirculation (EGR) system controls the oxides of nitrogen (NOx) emissions. To lower NOx emissions, the temperature in the combustion chamber must be decreased. This is accomplished by recirculating small amounts of exhaust gases back into the combustion chamber to mix with the air/fuel charge.




Operation
- The Differential Pressure Feedback EGR system receives signals from Engine Coolant Temperature (ECT) sensor; Intake Air Temperature (IAT) sensor, Throttle Position (TP) sensor, Mass Air Flow (MAF) sensor and Crankshaft Position (CKP) sensor to provide information on engine operating conditions to the PCM.
- The engine must be at normal operating temperature, stable and running at a moderate load and rpm before the EGR system is activated.
- The PCM deactivates the EGR during idle, extended wide open throttle or whenever a failure is detected in an EGR component or EGR required input.