Emission Control Systems: Description and Operation

EGR Valve:

EGR Solenoid And EGR Vent Solenoid:

DESCRIPTION
The Exhaust Gas Recirculation (EGR) system lowers the formation of nitrogen oxides by reducing combustion temperature. This is done by introducing exhaust gases into the cylinders through an EGR valve. The Powertrain Control Module (PCM), in the control module system, controls the amount of EGR to meet emission control requirements and maintains good driveability through an EGR solenoid and EGR vent solenoid, which regulates the vacuum to the EGR valve. One main sensor input to the PCM is used to calculate the amount of EGR.

The EGR valve, installed on the intake manifold, introduces the exhaust gases to the incoming fresh air at the engine crossover. A vacuum pump is required to provide a vacuum source to operate the EGR system. An EGR control pressure/Barometric Absolute Pressure (BARO) sensor mounted on the right side of the plenum panel is used to measure the amount of absolute pressure in the EGR vacuum line.