Engine Controls - Theory & Operation: Overview Infiniti G20 II

EGR System Description

EGR system is used to reduce tailpipe emissions of NOx (oxides of nitrogen), reduce engine knock and lower combustion chamber temperature. A portion of exhaust gases from the exhaust manifold is returned to the intake manifold and then the combustion chamber to dilute air/fuel mixture, therefore lowering cylinder temperature. ECM controls operation of EGR system through EGR Control (EGRC) solenoid valve or EGR Volume Control Valve (EGR-VCV). EGR system does not operate under the following conditions

1. Engine starting.
2. Engine stopped.
3. Engine Idling.
4. High engine speed (G20).
5. Low battery voltage (G20).
6. Low or excessively high engine coolant temperature.
7. Low or high vehicle speed (Q45).
8. Mass airflow (MAF) sensor malfunction (Q45).
9. Wide open throttle (G20).