49-State Models

Flow Diagram:

PURPOSE
The Exhaust Gas Recirculation (EGR) system controls Nitrous Oxide (NOx) emissions. Metered 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.

OPERATION
The EGR system is enabled only during part throttle modes when the engine is warm and stabilized. The Throttle Position (TP) sensor indicates part throttle, and Engine Coolant Temperature (ECT) sensor indicates a warm engine. The Powertrain Control Module (PCM) controls EGR function necessary to avoid driveability concerns during idle and maximum power demands. The PCM compensates for changes in the air/fuel ratio when EGR gases are introduced.