Exhaust Gas Recirculation: Description and Operation

PURPOSE
The EGR system returns a portion of the exhaust gas to the intake manifold to reduce the combustion temperature. This results in a reduction of the Oxides of Nitrogen (NOx) that are produced.





OPERATION
The PCM controls the EGR vacuum regulator solenoid. The EGR vacuum regulator solenoid controls the vacuum to the EGR valve. When the EGR valve opens, exhaust gas flows to the intake manifold. The EGR backpressure transducer measures the flow through the EGR valve to exhaust manifold tube and sends a signal to the PCM. A metering orifice in the EGR valve to exhaust manifold tube restricts the flow rate when the EGR valve is open.

EGR SYSTEM COMPONENTS





EGR valve to exhaust manifold tube:
- Connects the exhaust manifold to the EGR valve.
- Has two tubes connecting to the EGR backpressure transducer for EGR flow monitoring.





EGR Backpressure Transducer:
- Monitors the EGR flow rate through the EGR valve to exhaust manifold tube.
- Sends an EGR flow rate signal to the PCM.





EGR Vacuum Regulator Solenoid
- The EGR vacuum regulator solenoid uses input from the PCM to change the EGR valve operation.