Exhaust Gas Recirculation: Description and Operation: Overview

Overview

The Exhaust Gas Recirculation (EGR) system controls the Oxides Of Nitrogen (NOx) emissions. Small amounts of exhaust gases are recirculated back into the combustion chamber to mix with the air/fuel charge. The combustion chamber temperature is reduced, lowering NOx emissions.

The EGR system:
^ returns a small amount of exhaust gas into the engine for composition.
^ reduces the overall combustion temperature and provides a significant reduction of oxide of nitrogen (NOx).

The EGR valve:
^ is electronically controlled by the Powertrain Control Module (PCM).
^ controls the vacuum to the EGR valve.

The EGR valve:
^ is connected to the exhaust manifold by the EGR valve to exhaust manifold tube.
^ controls recirculated exhaust gas flow to the intake manifold.
^ monitors the flow of recirculated exhaust gases through the EGR valve to exhaust manifold tube.
^ returns a signal to the powertrain control module.

The amount of recirculated exhaust gas depends upon:
^ engine rpm.
^ intake manifold vacuum.
^ exhaust back pressure.
^ engine coolant temperature.
^ throttle position.

The vehicle emission control information (VECI) decal:
^ is located on the hood.
^ lists the exhaust emission control system information.