Exhaust Emissions System - Exhaust Gas RECIRCULATION: Description

On 6-cylinder engine, the EGR system is used to reduce emission of oxides of nitrogen (NOx). The EGR valve is mounted on exhaust manifold and controls flow of exhaust gases into intake manifold. The control signal is taken form a throttle edge tapping, which gives no exhaust gas recirculation at idle speed or full load.

On V12 engine, the exhaust gas recirculation system is controlled by two solenoid-operated valves which are mounted near the outside center of each exhaust manifold. These valves meter a proportion of exhaust gas into the induction system during certain engine modes. The gas is diverted from the exhaust pipe downstream at a tapping ahead of the catalytic converters, and fed through valves and fixed orifices in the induction system.

Fig 1: 6-Cylinder Engine EGR Valve Location

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

Fig 2: V12 Engine EGR System Electrical Schematic

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

The signal that operates the EGR valves is determined by the position of the throttle switch. There is no recirculation at idle and full throttle. Recirculation is also restricted by a coolant temperature valve which does not allow exhaust gas flow through the EGR system until coolant is above 95°F (35°C). Also, above 60-65 MPH, there is no EGR. These functions are controlled by the EGR controller mounted inside the luggage compartment, behind the right-rear light cluster. See Fig 2.