Jaguar XJ (X350). Manual — part 770

Exhaust Manifold to Exhaust Gas Recirculation (EGR) Valve Tube

The exhaust gas recirculation (EGR) system is fitted on all vehicles fitted with a 3.5L or 4.2L engine. It

comprises of an EGR valve and exhaust manifold to EGR valve tube. The EGR system allows a

measured quantity of exhaust gas to be directed back to the intake manifold. The exhaust gas is

introduced to the incoming charge in the intake manifold, where it mixes with the air/fuel mixture

and lowers the peak gas temperature, reducing nitrogen oxide (NOX) exhaust emissions. The gas is

drawn through the exhaust manifold to EGR valve tube from the exhaust to the inlet manifold via the

EGR valve. The EGR valve is electrically operated and is controlled via an input from the engine

control module (ECM).

On vehicles without supercharger the EGR valve is mounted on the intake manifold. On vehicles with

supercharger the EGR valve is mounted on the throttle body elbow.

The ECM can monitor the operation of the EGR system by receiving inputs from the manifold

absolute pressure (MAP) sensor. The MAP sensor monitors the EGR flow by the change in intake

manifold pressure when the EGR valve is operated. If at any time the input signal to the ECM exceeds

pre-defined thresholds due to low pressure reading for a calibrated period of time, a diagnostic

trouble code (DTC) is recorded.

On vehicles without supercharger the MAP sensor is mounted on the rear of intake manifold. On

vehicles with supercharger the MAP sensor is mounted on the rear of the throttle body elbow.

<<303-14B>>

Engine Emission Control - VIN Range:
G45704->G99999

Positive Crankcase Ventilation (PCV) System

The PCV system recycles crankcase gases back through the engine where they mix with incoming

air/fuel charge and help to reduce hydrocarbon emissions.

Vehicles with 3.0L engine

The PCV system consists of two hoses, connected between the left-hand valve cover and the intake

manifold and the right-hand valve cover and the air cleaner outlet pipe.

Vehicles with 3.5L or 4.2L engine

The PCV system consists of a valve, and two hoses. The PCV valve is mounted on the right-hand valve

cover and a hose is connected between PCV valve and the throttle body elbow. The left-hand valve

cover PCV hose is connected to the air cleaner outlet pipe.

The PCV valve regulates the amount of ventilation air and crankcase gas supplied to the intake

manifold and also prevents backfiring into the crankcase.

Exhaust Gas Recirculation (EGR) System - Vehicles with 3.5L or 4.2L engine

EGR Valve

EGR Valve Tube

The EGR system comprises of an EGR valve and exhaust manifold to EGR valve tube. The EGR system

allows a measured quantity of exhaust gas to be directed back to the intake manifold. The exhaust

gas is introduced to the incoming charge air in the intake manifold, where it mixes with the air/fuel

mixture and lowers the peak gas temperature, reducing nitrogen oxide (NOx) exhaust emissions. The

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gas is drawn through the exhaust manifold to EGR valve tube from the exhaust to the inlet manifold

through the EGR valve. The EGR valve is electrically operated and is controlled through an input from

the engine control module (ECM).

On vehicles without a supercharger the EGR valve is mounted on the intake manifold. On vehicles

with a supercharger the EGR valve is mounted on the throttle body elbow.

The ECM monitors the operation of the EGR system from inputs from the manifold absolute pressure

(MAP) sensor and can detect high or low flow through the valve as a result of changes to the

pressure readings.

High or low flow outside the expected range results in the setting of a diagnostic trouble code (DTC).

On vehicles without a supercharger the MAP sensor is mounted on the rear of intake manifold. On

vehicles with a supercharger the MAP sensor is mounted on the rear of the throttle body elbow. For

additional information, refer to Electronic Engine Controls (303-14B)

Secondary Air Injection (AIR) System

To assist in the reduction of exhaust emissions to meet European Union (EU) Stage 4 and Federal

Petrol Emission standards, AIR is fitted to the vehicle.

Item

Part Number

Description

1

AIR vacuum reservoir

2

AIR switching valve

3

Exhaust manifolds

4

AIR pump

5

AIR control valve

The AIR pump is used to provide a supply of air into the exhaust manifolds during the cold start

period of the engine. The AIR cycle lasts for up to 65 seconds. The hot unburnt fuel particles leaving

the combustion chamber mix with the air injected into the exhaust manifolds and immediately

combust.

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