General Systems Description

EGR Valve:

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 though the EGR solenoid and vent solenoid, which regulates the vacuum to the EGR valve. One main sensor input to the PCM is used to calibrate the amount of EGR.

OPERATION
The EGR valve, installed in 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.

The Adaptive Learn Matrix (ALM) is used to adjust the EGR vacuum control based on Mass Air Flow (MAF). The ALM may change as a result of back pressure increases over the life of the vehicle or other engine system variations. The ALM is made up of sixteen cells (numbered from zero to fifteen) in which each cell covers a range of engine speed (RPM) and load (mm3).