Jaguar XJ (X350). Manual — part 971

Description and operation

Electronic Engine Controls

Item

Part Number

Description

1

Mass air flow (MAF) sensor(s)

2

Knock sensor (KS) Right-hand

3

Manifold absolute pressure (MAP) sensor

4

Fuel temperature sensor

5

Knock sensor (KS) Left-hand

6

Camshaft position (CMP) sensor

7

Crankshaft position (CKP) sensor

8

Engine oil pressure (EOP) sensor

9

Engine coolant temperature (ECT) sensor

10

Charge air temperature sensor

Item

Part Number

Description

1

Engine control module (ECM)

System Components

All engine functions are controlled by the Siemens common rail ECM.

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ECM

The ECM is a high capacity processor which employs advanced software strategies that continuously

control the engines operating parameters. It gathers information from a number of sensors and

provides output to the actuators. The ECM also operates a port deactivation system, which closes or

opens flaps in the inlet system to provide the optimum swirl and flow conditions throughout the

operating range of the engine.

In addition, the ECM controls the actuation of the exhaust gas recirculation (EGR) system, the

variable geometry turbochargers and the throttle, giving faster and more accurate response. A full

torque-based strategy supports multiple injection control and integration with transmission and

braking controllers. Transient torque and boost control enables vehicle performance to be optimised

without compromising engine durability.

CKP Sensor

The CKP sensor signal is used to determine:

the quantity of fuel to be injected

the start of fuel delivery

the quantity of exhaust gases to be recirculated

The CKP sensor is located at the rear of the crankshaft behind the flywheel.

The CKP sensor is a Hall effect sensor which scans a magnetic disc on the crankshaft. The air gap

between the magnetic disc and the CKP is predetermined by the mounting of the sensor.

CMP Sensor

The CMP is located on the cylinder head behind the left-hand camshaft timing belt pulley.

The CMP sensor is Hall effect type and is required to identify cylinder number 1. (This is to

synchronise engine to camshaft timing). The sensor scans a web incorporated into the left- hand

camshaft timing belt pulley. The air gap between the magnetic ring and the CMP sensor is

predetermined by the mounting of the sensor.

ECT Sensor

The ECT sensor is a NTC type sensor and is fitted into the top water outlet hose. The sensor has a

bayonet type fitting.

KS

The KS registers increased vibrations which occur due to increased combustion noise. The ECM uses

the signal as a correction factor for calculating the quantity and timing of the fuel to be injected

during the injection phase.

There are two KS fitted to each bank of the cylinder block.

MAF Sensor

The MAF sensor is used to calculate the air mass. The MAF sensor is capable of detecting the mass air

flow extremely precisely.

On engines with a variable turbocharger, the MAF sensor is used solely to control the EGR and not

the fuel metering. The MAF sensor also incorporates the intake air temperature (IAT) sensor.

MAP Sensor

The MAP sensor is located in the top of the throttle valve.

The MAP sensor measures the charging pressure in the intake pipe and sends the ECM an analog

voltage signal.

Charge Air Temperature Sensor

The charge air temperature sensor measures the intake air or the charge air temperature and

supplies the ECM with an analog signal.

The charge air temperature sensor is located in the air intake plenum chamber.

Intake Air Temperature (IAT) Sensor

The IAT sensor measures the intake air temperature and supplies the ECM with an analog signal.

There are two IAT sensors incorporated into the MAF sensor, the Left-hand bank IAT sensor is not

monitored by the ECM.

Fuel Rail Pressure (FRP) Sensor

The FRP sensor measures the instantaneous fuel pressure in the fuel rail very precisely within a very

short time and supplies a voltage signal according to the pressure. The FRP is located on the the fuel

diverter rail and must not be removed from the diverter rail. For additional information, refer to Fuel

Charging and Controls (303-04C Fuel Charging and Controls - 2.7L Diesel)

Fuel Temperature Sensor

The fuel temperature sensor measures the temperature of the fuel in the low-pressure system. Air

and excessive heat in the fuel system can have an adverse effect on the operation of the sensor.

The fuel temperature sensor is located in the low-pressure side return line behind the throttle body

housing.

EOP Sensor

The engine oil pressure (EOP) sensor is located in the left-hand cylinder head. The EOP is connected

to the instrument cluster and is not directly part of the electronic engine control system.

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