Diesel Engine Management Systems

Diesel Engine Management Systems
Steve Baker

Basic Diesel Fuel Delivery System
1. Fuel Return Line 2. Fuel Injection Pump 3. Injectors 4. Fuel Filter 5. Fuel Tank 6. Swirl Pot 7. Fuel Feed Line General Fuel is drawn from the tank by the injection pump via a filter on the engine compartment bulkhead. The fuel feed line, between the tank and the injection pump, can be primed using a rubber priming bulb on the side of the filter and a bleed screw on the injection pump. The injection pump pressurises and distributes precisely timed, exact quantities of fuel to the injectors in response to control inputs from the ECM. Any excess fuel is passed back to the tank via the fuel return line. Diesel engines operate on the compression ignition principle. Air induced into the cylinder is compressed by the upward movement of the piston on its compression stroke. When air is compressed, heat is generated making an ideal environment for combustion. Finely atomised diesel fuel is injected into the combustion chamber, where it freely mixes with the compressed, and now rapidly heated charge of induced air. The heat generated by the compression of the air and the introduction of a precise amount of atomised diesel fuel causes spontaneous combustion just prior to the piston reaching Top Dead Centre (TDC). Low Pressure High Pressure Spill Return

Air Intake System Air Intake System
The engine is supplied with pre-compressed air by a single stage turbocharger. Turbocharger With the engine running, exhaust gases pass into the turbine side of the turbocharger, causing the turbine to rotate and drive a compressor mounted in the air intake ducting. Intercooler Intake air is drawn through the air cleaner to the turbocharger, where it is compressed by the compressor. The compressed air is then fed into the inlet manifold via an intercooler, which reduces the temperature and increases the density of the compressed air.

Engine Management Systems
L- Series 2.0 Litre EDC 15 M47R 2.0 Litre DDE4

Advantages of EDC Greater Fuel Economy Reduced Exhaust Emissions
Reduced Engine Noise More Effective Cold Starting Smoother Engine Operation Electronic Diesel Control A purely mechanical fuel injection system would not be accurate enough to comply with the increasing stringency of exhaust emission legislation. This has lead to the development of a fully functional diesel specific diesel engine management system known as electronic diesel control 15 (EDC 15). The system is controlled by an engine control module (ECM) and is able to monitor, adapt and control the fuel injection precisely. In order for set emission limits to maintained, the EDC system uses multiple sensor inputs and precision control of actuators to achieve optimum performance during all driving conditions. The advantages of EDC are as follows: • Greater fuel economy • Reduced exhaust emissions • Reduced engine noise • More effective cold starting • Smoother engine operation The EDC 15 system is very similar to that of the EDC system fitted to the Rover 400 and the more powerful version of the Rover 200 L series engine. Some of the changes are as follows: • A new higher pressure pump containing an ECU which controls the amount of fuel injected and the exact point of ignition. • A new air flow meter • A new throttle position sensor • A new manifold absolute pressure sensor The ECM controls the delivery of fuel to all four cylinders via a CAN link to the fuel injection pump.

Electronic Control Module (ECM)
The ECM consists of an Integrated Circuit (IC) installed in an alloy casing. Two electrical connectors provide the interface between the IC and the engine harness. The ECM is installed in the engine compartment on the side of the battery carrier. In addition to calculating the fuel injection quantity and timing, the ECM also controls the operation of the:- • Glow plugs. • Exhaust Gas Recirculation (EGR) system • Air Conditioning (A/C) compressor (where fitted). • Cooling fan(s). The ECM incorporates short circuit protection and can store intermittent faults on certain inputs. TestBook can interrogate the ECM for these stored faults via the diagnostic socket. If certain system inputs fail, the ECM implements a back-up facility to enable the system to continue functioning, although at a reduced level of performance. As part of the security system’s immobilization function, a vehicle specific security code is programmed into the ECM and alarm ECU during production. The ECM cannot function unless it is connected to an alarm ECU with the same code. In service, replacement ECM are supplied uncoded and must be programmed using TestBook to learn the vehicle security code from the alarm ECU.

EDC 15 System Inputs

Crankshaft Position Sensor (CKP)
Crankshaft Position (CKP) Sensor The speed and position of the engine is detected by the CKP sensor which is bolted to, and projects through, the gearbox adaptor plate adjacent to the flywheel. The CKP is an inductive sensor consisting of a bracket mounted body containing a coil and a permanent magnet which provides a magnetic field. The sensor is situated such that an air gap exists between it and the flywheel. Air gap distance is critical for correct operation. The flywheel has four holes positioned equally around the crankshaft circumference at 90 degree intervals. When the flywheel rotates, as a hole passes the sensor it disturbs the magnetic field inducing a voltage pulse in the coil. This pulse is transmitted to the engine control module. Four pulses are transmitted to the ECM for each revolution of the flywheel. By calculating the number of pulses that occur within a given time, the ECM can determine the engine speed. The output from this sensor when used in conjunction with that from the needle lift sensor is used for idle stabilisation and reference for injection timing.

Injector Needle Lift Sensor
The ECM uses the input signals from the needle lift sensor to close the injection timing loop. The needle lift sensor consists of a coil which surrounds the shaft of an extended injection needle on No.1 fuel injector. The coil is fed a DC supply from the ECM and produces a magnetic field. When the needle is moved under the influence of fuel pressure, the magnetic field is disturbed which induces an AC voltage in the coil. The induced voltage is registered in the ECM as a reference point for the start of fuel injection.

Coolant Temperature Sensor (ECT)
 Coolant Temperature Sensor (ECT) The ECT sensor is a thermistor located in the top of the coolant outlet elbow. The ECM constantly monitors the signal and uses the information to correct the quantity of fuel injected and the injection timing especially during cold starting. During starting, output from the sensor determines how long the glow plugs are energised. Cº V Cº

Manifold Absolute Pressure Sensor (MAP)
The pressure of the intake air is monitored by a sensor located on the bulkhead and connected, via a pressure tube, to the outlet side of the turbocharger. The sensor is connected electrically to the ECM. The ECM supplies a reference voltage to the sensor and translates the return signal into a pressure value. When the intake air pressure changes, the resistance across the sensor changes and affects the value of the return signal.

Throttle Potentiometer
Accelerator Pedal Position Sensor The accelerator pedal position sensor transmits accelerator pedal position (i.e. driver demand) to the ECM. The sensor is installed on a bracket attached to the driver’s side front inner wing and connected to the accelerator pedal by a Bowden cable. A flying lead and connector from the base of the sensor provides the interface with the vehicle wiring. The accelerator pedal position sensor consists of an inductive position sensor together with an idle switch. With the accelerator pedal released the idle switch is open. When the accelerator pedal moves enough to rotate the shaft of the sensor more than 9° the idle switch closes. The idle switch signal is used by the ECM to implement idle speed control and overrun fuel cut off, and to check the plausibility of the position sensor signal. When the idle switch closes the ECM compares the signal voltage with a pre-programmed value. Accelerator pedal movement causes the voltage of the position sensor output to vary. The ECM calculates the rate of change of the voltage in positive (acceleration) or negative (deceleration)n directions. From this the ECM can determine the required engine speed, rate of acceleration or rate of deceleration and apply acceleration enrichment, deceleration fuel metering or over-run fuel cut-off as appropriate. The ECM calculates a ’driver demanded fuel quantity’ from the position sensor input. The ECM also calculates a ’maximum allowable fuel quantity’ based on mass air flow, engine speed, coolant temperature and strategies such as smoke limitation, active surge damping and fuel reduction. If the driver demanded fuel quantity is less than the maximum allowable fuel quantity then the driver demanded fuel quantity is injected. However, if the driver demanded fuel quantity is greater than the maximum allowable fuel quantity, then the maximum allowable fuel quantity is injected rather than that demanded by the driver.

Brake Pedal Switch Brake Pedal Switch
The brake pedal switch informs the ECM when the vehicle is braking and allows it to implement active surge damping. The normally open switch closes when the brake pedal is pressed and supplies a 12V feed to the ECM. The ECM checks the plausibility of the brake switch input by comparing it with the input from the accelerator pedal position sensor. If the inputs indicate the brake pedal is pressed at the same time as the accelerator pedal, the ECM interprets this as a fault.

Inlet Air Temperature/Mass Air Flow Sensor (IAT/MAF)
The IAT/MAF sensor supplies the ECM with separate signals for mass air flow and intake air temperature. The sensor is installed in the intake duct, between the air cleaner and the turbocharger. The mass air flow is determined from the cooling effect of the intake air flowing over a hot film resistor. The temperature is determined from the output of a thermistor. The ECM monitors the signals from the sensor and equates them to mass air flow and temperature values.

Immobilisation Signal
The anti-theft alarm ECU is has a security code embedded in the ECU memory. During vehicle assembly the ECM learns the security code for the ECU fitted, making the two units a matched pair. When the ECU senses an ignition on signal and the alarm system is disarmed, the ECU provides an earth path for the starter relay coil, allowing starter operation. Simultaneously, the ECU also continuously transmits a serial code to the ECM. This is achieved by the ECU repeatedly opening and closing the earth for the serial communications wire at 125 millisecond intervals. If the ECU senses an ignition on signal, but the alarm system is still armed, the earth for the starter relay coil is not granted and the serial communications wire to the ECM is held to earth. If the ECM receives the wrong code from the ECU or no code at all it will allow the engine to run for approximately one second. The ECM then stops firing the injectors, stopping the engine. The ECM will not allow the engine to run until the ignition has been off for approximately thirty seconds and once the ignition is switched on, the correct code is received. NOTE: The ECM only requires to receive the correct code once to allow the engine to run in one ignition cycle. Any failure of the ECU during engine running will not stop the engine. If the anti-theft alarm ECU or the ECM are changed, the codes in the units will not match and the ECM will behave as described for an incorrect code above. TestBook/T4 is required to enable the ECM to learn the security code from the ECU.

Vehicle Speed Sensor Vehicle Speed Sensor
The vehicle speed sensor is located on the top of the differential housing. The vehicle speed sensor is driven by the final drive gear and produces an electrical signal proportional to road speed. The output from the vehicle speed sensor is used to drive the instrument pack speedometer in addition to providing a signal to the ECM. The ECM uses this signal to provide active surge damping and to adjust idle stabilisation.

Inputs Air Con Request Ignition Switch Ignition Switch
When the ignition switch is turned to position II a power feed is connected from the ignition switch to the ECM. The ECM then initiates ’wake up’ routines and energises the main relay and the glow plug relay. Provided a valid mobilisation signal is received from the alarm ECU, the ECM also connects the fuel shut-off power supply to the pump ECU to enable fuelling. If no mobilisation code is received from the alarm ECU, or the code is invalid, the ECM withholds the fuel shut-off power supply to prevent fuelling.

Inputs Trinary Switch Evaporator Temperature Sensor
The evaporator temperature sensor is an encapsulated thermistor that provides the ECM with an input of the evaporator air outlet temperature. If the temperature at the evaporator falls low enough for ice to form on the fins, the ECM withholds or discontinues engagement of the compressor clutch. When the temperature at the evaporator rises sufficiently, the ECM engages the compressor clutch. Refrigerant Pressure Sensor The refrigerant pressure sensor is located on top of the receiver/ drier and provides the ECM with a pressure input from the high pressure side of the refrigerant system. whenever the air conditioning system is switched on, provided the system pressure is correct. • The upper pressure limit is 29 bar (421 lbf/in 2 ), e.g. due to a blockage. Compressor engagement is re-enabled when the pressure decreases to 23 bar (334 lbf.in 2 ). • The lower pressure limit is 1.6 bar (23.2 lbf/in 2 ), e.g. due to a leak. Compressor engagement is re-enabled when the pressure increases to 2.0 bar (29.0 lbf/in 2 ).

System Outputs

Glow Plug Glow Plugs The glow plugs assist starting by pre-heating the air in the cylinders. A glow plug is installed in each cylinder, on the LH side of the cylinder head. The glow plugs are connected in parallel to a feed from the glow plug relay and earthed to the engine through the glow plug body. Operation of the glow plug relay is controlled by the ECM. When the starter switch is turned to position ’II’ the ECM energises the glow plug relay and illuminates the glow plug warning lamp in the instrument pack. The length of time the glow plug relay is energised depends on the engine temperature determined by the ECM from the ECT sensor. Once the glow plug relay has operated for the calculated time the ECM de-energises the glow plug relay and extinguishes the glow plug warning lamp. If the engine is cranked before the calculated time has elapsed, the ECM immediately de-energises the glow plug relay and extinguishes the glow plug warning lamp.

Malfunction Indicator Lamp (MIL)
Warning Lamps There are two engine management related warning lamps in the instrument pack: an amber glow plug warning lamp and an amber engine malfunction lamp. The glow plug warning lamp illuminates while the glow plugs are energised at the start of the ignition cycle. The engine malfunction lamp illuminates if there is a fault with the ECM, fuel injection pump ECU or a critical engine sensor NOTE: An amber Malfunction Indicator Lamp (MIL) is installed in the instrument pack for future use. Although the ECM performs a bulb check on the MIL when the ignition is first switched on, the MIL is not yet operational.

Air Conditioning Compressor Switching
Input Component Off On Accelerator Pedal Position Sensor Above 85 Below 80 ECT Sensor 118c (244f) 112c (234f) A/C Pressure Sensor Low Limit High Limit 1.6 Bar(23.2psi) 29 Bar (421 psi) 2.0 Bar (29 psi) 23 Bar (334 psi) Air Conditioning Compressor Operation When A/C is requested on the A/C switch, the ECM grants the request by energising the A/C compressor clutch relay provided that: • Driver demand is less than wide open throttle. • The engine coolant temperature is within limits. • There is no engine running problem. • The engine is running below the maximum permitted continuous speed. • The input from the A/C pressure switch indicates that refrigerant system pressure is within the upper and lower limits. • The input from the evaporator temperature sensor indicates that the temperature of the air leaving the evaporator is above the minimum limit, i.e. the evaporator is free from ice. When it energises the A/C compressor clutch relay, the ECM also operates the cooling and condenser fans at slow speed. When the input from the A/C pressure switch indicates that the refrigerant system requires additional cooling, the ECM switches the cooling and condenser fans to operate at high speed. While the A/C is on, if the throttle position, engine coolant temperature or refrigerant system pressure exceed preset limits the ECM de-energises the A/C compressor clutch relay to suspend A/C operation and reduce the load on the engine. When the parameter returns within limits the ECM re-energises the A/C compressor clutch relay to restore A/C.

Cooling Fan Switching Input Component Fan Speed On Off ECT Sensor:
A/C Models Non A/C Models Low High 104°c(219°) 112°c(234°) 98°c (208°f) 106°c (223°f) A/C Switch With Switch A/C Pressure Sensor 19 Bar (275 psi) 14 Bar (203psi) Cooling Fan Operation The ECM controls the operation of the engine and condenser cooling fans by switching relays. On non A/C models, the ECM switches a single relay in the engine compartment fuse box to run the engine cooling fan at high speed. On models with A/C, in addition to the relay in the engine compartment fuse box, the ECM also operates two relays on the outside of the battery box to run the engine cooling fan and the condenser cooling fan together, at either low or high speed. The ECM operates the cooling fan(s) in response to inputs from: • The ECT sensor, for engine cooling. • The A/C switch and A/C pressure sensor, for refrigerant system cooling. On vehicles with A/C, if there is a conflict between requested cooling fan speeds from the different inputs, the ECM adopts the highest requested speed. During the power down after the ignition is switched off, the ECM monitors the engine coolant temperature for 4 minutes. Within that time, if the engine coolant temperature exceeds 112 °C (234 °F) the ECM operates the cooling fan(s) for 8 minutes or until the engine coolant temperature decreases below 106 °C (223 °F), whichever occurs first. Similarly, if the cooling fan(s) are already running when the ignition is switched off, the ECM operates them for 8 minutes or until the engine coolant temperature decreases below 106 °C (223 °F).

Fuel Injection Pump Fuel Inlet Fuel Outlet (Spill)
Timing Device Plunger Fuel Injection Pump The fuel injection pump is an electronically controlled distributor pump installed on the gearbox adaptor plate. The pump is driven at half engine speed by a toothed drive belt from the rear end of the camshaft via a drive pulley attached to the pump drive shaft.

Fuel Injection Pump ECU (micro controller) Axial Piston
Distributor Sleeve Hydraulic Head Fuel Quantity Solenoid Valve Outlet to Fuel Injector Non Return Valve Timing Device Solenoid Fuel Injection Pump In the pump housing the drive shaft is coupled to a four lobe cam plate and an axial piston. Springs, acting on a flange on the axial piston, hold the axial piston against the cam plate and the cam plate against four rollers mounted on a timing ring. The timing ring is connected to a timing device consisting of a plunger and a solenoid valve. A toothed wheel and a vane type supply pump are installed on the drive shaft. The toothed wheel is aligned with a timing sensor connected to the timing ring, and has teeth at 3° intervals, except for 12° synchronisation gaps opposite each lobe of the cam plate. Passages in the pump housing connect the supply pump to the fuel inlet from the tank and to the intermediate chamber containing the timing ring, cam plate and axial piston. A pressure regulator valve is connected between the inlet and outlet sides of the supply pump. The end of the axial piston locates in a distributor sleeve attached to the hydraulic head of the pump housing. Passages in the distributor sleeve and the hydraulic head connect four equally spaced points around the axial piston to individual outlets to the fuel injectors. A check valve is installed in each of the fuel outlets. Further passages in the hydraulic head connect a pumping chamber at the end of the axial piston to a fuel supply from the intermediate chamber and to a fuel return port on the pump exterior. The fuel supply and return flows are controlled by a fuel quantity solenoid valve. An ECU is attached to the exterior of the pump housing and connected to the engine harness.

Fuel Injection Pump 12. Timing Device Solenoid Valve
13. Intermediate Chamber 14. Cam Plate 15. Timing Ring 16. Toothed Wheel 17. Supply Pump 18. Drive Pulley 19. Drive Plate Fuel Injection Pump Wires, inside protective sleeving attached to the outside of the pump housing, connect the ECU to the timing device solenoid valve and the fuel quantity solenoid valve. A conductive foil connects the ECU to the timing sensor. A temperature sensor in the ECU senses the temperature of the pump housing. The input from the timing sensor is used by the pump ECU to determine the position and speed of the cam plate. The cam plate position is used to coordinate operation of the fuel quantity solenoid valve and for injection timing and quantity control. The cam plate speed is used in the cam plate position calculations, to determine positions between the 3° intervals of the toothed wheel. To check the plausibility of the timing sensor signal, the pump ECU compares cam plate speed with the input from the engine speed sensor.

Can Bus Messages Fuel Injection Pump Operation
When the drive shaft of the fuel injection pump turns, fuel is drawn from the tank by the supply pump and supplied to the intermediate chamber. The incoming fuel flows through a chamber beneath the ECU to keep the ECU cool. The supply to the intermediate chamber is regulated at 8 to 10 bar (120 to 145 lbf/in 2 ) by the pressure regulator valve. In the intermediate chamber, the fuel cools and lubricates the cam ring, cam plate and axial piston. A permanent flow of fuel passes from the intermediate chamber through the passages in the hydraulic head to the tank return line. The flow cools the fuel quantity solenoid valve and ensures there is a constant supply of fuel for the pumping chamber. Maximum return flow rate is 70 litres/hour (15.4 galls/hour). As the cam plate and the axial piston turn with the drive shaft, the lobes of the cam plate ride over the rollers on the timing ring and produce a reciprocating movement of the axial piston. Due to the four lobes on the cam plate, the axial piston moves through four inlet and compression stroke cycles per pump revolution. On sequential compression strokes a passage in the rotating axial piston connects the pumping chamber to the appropriate fuel injector outlet, in engine firing sequence.

Can Bus Messages Fuel Injection Pump Operation
During each inlet stroke of the axial piston, the fuel quantity solenoid valve is open to allow fuel from the intermediate chamber into the pumping chamber. At the beginning of the compression stroke, the pump ECU closes the fuel quantity solenoid valve. The axial piston then pressurises the fuel in the pumping chamber and thus the line to the appropriate fuel injector. When the pressure is sufficient to operate the fuel injector, the needle valve in the fuel injector opens and an atomised spray of fuel is injected into the engine cylinder. When the required quantity of fuel has been injected, the pump ECU opens the fuel quantity solenoid valve. This releases the pressure in the pumping chamber and the needle valve of the fuel injector closes to stop fuel injection. During the compression stroke of the axial piston, the maximum pressure produced in the pumping chamber is approximately 780 bar (11300 lbf/in2 )at a rated speed of 2100 rev/min. The rapid movement of the piston produces shock waves in the fuel between the pumping chamber and the fuel injector. The length of each fuel pipe, between the injection pump and the fuel injector, is tuned to the frequency range of the shock waves, which increases the pressure at the fuel injector to approximately 1200 bar (17400 lbf/in2 ) at rated speed. Injection Quantity Fuel injection quantity is controlled by varying the length of time that the fuel quantity solenoid valve is energised closed during the compression stroke of the axial piston. The flow rate of the injected fuel is controlled by varying the points on the cam lobe at which the fuel quantity solenoid valve closes and opens, since the profile of the lobe is non linear. Maximum injection duration at rated power is 17. 5° of cam plate movement (35° of crankshaft movement). Maximum possible injected quantity is 0.05 cc /stroke. Injection Timing The injection timing is adjusted by turning the timing ring. This alters the axial piston movement relative to the pump drive shaft and thus the engine. The control range of the timing ring is 15°(30° of crankshaft movement). The position of the timing ring is controlled by the pump ECU via the timing device. The plunger of the timing device is subjected to spring pressure and supply pump inlet pressure on one end, and to servo pressure at the other end. Servo pressure is derived from a restricted flow of supply pump outlet pressure. The pump ECU controls the servo pressure, and thus the position of the plunger and timing ring, using the timing device solenoid valve to regulate a bleed of servo pressure back to the inlet side of the supply pump. The pump ECU supplies the solenoid valve with a 50 Hz Pulse Width Modulated (PWM) signal and varies the duty cycle of the signal to adjust the bleed of servo pressure. The solenoid valve causes the characteristic buzzing from the fuel injection pump while the ignition is switched on. Injection timing is fully advanced with the solenoid valve de-energised. The ECM receives an injection timing feedback signal from the needle lift sensor in No. 1 fuel injector. If there is a significant difference between the injection timing indicated by the feedback signal and the injection timing requested on the CAN bus, the ECM assumes a fault exists and reduces the quantity of fuel injected.

Can Bus Messages Fuel Injection Pump Operation Fuel Shut-off
When the ignition is switched on, the ECM outputs a fuel shut-off power supply to the pump ECU to enable control of the normally open fuel quantity solenoid valve. When the ignition is switched off, or a serious engine problem is detected, the ECM disconnects the fuel shut-off power supply. Without the fuel shut-off power supply the fuel quantity solenoid valve is de-energised open, which prevents pressure generation in the pumping chamber and stops the supply of fuel to the injectors.

Exhaust Gas Recirculation
Exhaust Gas Recirculation (EGR) System During certain running conditions the EGR system directs exhaust gases into the intake manifold to be used in the combustion process. The principal effect of this is to reduce combustion temperatures, which in turn reduces Oxides of Nitrogen (NOx) emissions. The EGR diaphragm valve is vacuum operated through a solenoid valve, mounted on the engine bulkhead. When the ECM determines that exhaust gas recirculation should take place, the solenoid valve is modulated and vacuum, supplied by the brake servo vacuum pump, opens the EGR valve. Exhaust gases are then fed through a pipe into the inlet manifold via an EGR cooler. The air flow meter, mounted in the air intake pipe, senses the volume of air entering the engine. Using the principle that an increase in EGR decreases the intake air flow, the ECM uses the input from the air flow meter to monitor the amount of exhaust gases being recirculated. This feedback signal allows the ECM to accurately control EGR operation.

ROVER 25 EDC15M ECM OVERVIEW Notes

ROVER 25 EDC15M ECM FUELING Notes

ROVER 25 EDC15M ECM DRIVER DEMAND SENSORS Notes

ROVER25 EDC15M ECM INPUTS/OUTPUTS Notes

What Is Common Rail Injection?
A System Where All Injectors Are Fed Via a Shared Fuel Line First Developed by Elasis in Italy First Prototype System in 1993 Idea Bought & Developed by Bosch Common Rail Injection History A research company by the name of Elasis in Naples, developed common rail technology.In 1993 the Italians produced a prototype of their new fuel injection system. Problems with the tolerances of the injectors stopped the planned volume production and prompted the search for a partner at the turn of the year 1993/94. Bosch bought the patents and took over Elasis. Bosch presented the new system on the market one year earlier than any other manufacturers. Introduction In conventional systems, pressure generation is coupled to injection volume preparation. This has the following consequences for the injection characteristics: • The injection pressure increases as the speed and volume increase • The injection pressure increases during actual injection Consequently; • Small injection volumes are injected at lower pressures • Peak pressure is more than twice as high as the mean injection pressure The peak pressure governs the load on the components of an injection pump and the pump drive. On the other hand, the mean injection pressure is important for the quality of fuel-air mixture in the combustion chamber.

Advantages of Common Rail Injection
Fuel Injected at the Exact Time Required Precise Metering of Fuel Required Constant High Fuel Pressures Optimised Fuel Consumption Requirements Increasingly stringent regulations governing exhaust and noise emissions and the demand for lower fuel consumption mean that the injection system of a diesel engine must consistently fulfill new requirements. • Highest possible metering accuracy over the entire service life • Pre-injection and main injection • It is possible to independently determine the injection pressure and injection volume for every operating point of the engine which gives additional degree of freedom for ideal mixture preparation • The injection volume and pressure should be as low as possible at the start of injection to prevent ignition delay between the start of injection and the start of combustion to obtain smoother engine operation (pre-injection). Functional Principle The Rover 75 is the very first Rover diesel engine to be equipped with a high-pressure accumulator fuel injection system (common rail). With this new fuel injection process, a high-pressure pump delivers a uniform level of pressure to the shared fuel line (the common rail) which serves all the fuel injectors. Pressure develops to an optimum level for smooth operation. This means that each injector nozzle is capable of delivering fuel at pressures of up to 1350 bar. The common rail system disconnects fuel injection and pressure generation functions. Fuel injection pressure is generated independently of the engine speed and fuel injection volume and The fuel injection timing and fuel volume are calculated individually in the EDC control unit and delivered to each engine cylinder by the injectors, each of which is actuated by energising the appropriate solenoid valve.

Advantages of Common Rail Injection
Reduced Emissions Very Smooth Engine Operation Allows Two Stage Injection Advantages of Common Rail Injection 1. Fuel injection at exactly the right moment 2. Precisely metered fuel quantity 3. Constant high pressure 4. Fuel consumption optimised 5. Emission reduction 6. Very smooth engine operation 7. Pre-injection: • The ignition delay at the point of main injection is shortened • Combustion pressure peaks are reduced (Smoother combustion) • Emissions are reduced 8. Main injection: • Variable operating pressure according to engine demands • The injection pressure remains constant over the entire injection period thus enabling more accurate volume metering. • The main injection is responsible for torque generation is made available in the rail (high pressure fuel accumulator) for injection to the cylinders.

Injection Characteristics
Conventional Injection Characteristics In conventional injection systems, such as the use of distributor and in—line injection pumps, only a single injection takes place. Pressure generation is coupled to injection volume preparation. This has the following consequences for the injection characteristics: • The injection pressure rises as the engine speed and injection quantities increase • The injection pressure increases during injection As a result: • At low pressures small quantities are injected • The peak pressure is more than twice the average fuel injection pressure Peak pressure determines the load which can be applied to the components of an injector pump and its drive unit. The average injection pressure is, however, important for the quality of the fuel/air mixture in the combustion chamber. Common Rail Injection Characteristics Common rail fulfils the following demands: • It is possible to independently determine the injection pressure and injection volume for every operating point of the engine which gives an additional degree of freedom for the ideal mixture preparation • After the start of combustion, it should be possible to select the injection pressure throughout the entire period of injection Standard Common Rail

Fuel Delivery System Fuel Delivery Low Pressure (LP) Side
Fuel delivery starts at the plastic blow moulded fuel tank located under the floor in front of the rear axle. The fuel tank is of the 'saddle' design with a centre hump and two deep sections on either side of the vehicle. A submersible electric pump is located in the RH section of the fuel tank, this pump is called the primary LP fuel pump. The primary LP fuel pump draws fuel from a swirl pot and delivers it to a filter unit adapter mounted in the LH section of the fuel tank. The adapter unit contains a pressure regulator which is calibrated to 3.6 bar (52 lbf/in2 ), this will not open during normal operation of the system.

Fuel Delivery Schematic
1.Pressure Sensor and Fuel Filter 2.Pressure Relief Valve 3.High Pressure Injection Pump 4.In Line Electric Fuel Pump (Medium Pressure) 5.Bi-metallic By-pass Valve 6.Fuel Cooler 7.Fuel Pump Fuel Delivery – High Pressure (HP) Side The HP fuel pump supplies fuel to the fuel rail. The pump is directly driven by the engine and is located at the front of the engine block. Fuel rail pressure is variable to allow for fuelling strategies such as noise limitation and surge control. The maximum fuel pressure is 1300 bar (18850 lbf/in 2 ). Fuel pressure is controlled by the ECM via the fuel pressure regulator valve located at the rear of the HP fuel pump. The ECM uses the output signal from the fuel rail pressure sensor, mounted on the end of the fuel rail, to maintain the optimum fuel pressure for the current conditions. The fuel pressure regulator reduces pressure by diverting fuel from the HP output back to the fuel tank. The minimum operating pressures are 200 bar (2900 lbf/in2 ) during cranking and 300 bar (4350 lbf/in2 ) during idle, failure to reach these pressures will result in a non start situation, stalling or erratic idle. Fuel Return System The diverted fuel from the pressure regulator is hot, due to the pumping process within the HP fuel pump, and must be passed through a fuel cooler before it returns to the fuel tank. If the fuel is not over a predetermined temperature, a bimetallic bypass valve directs the fuel to the fuel tank. If the fuel temperature is above the predetermined temperature, fuel is directed back to the fuel tank via the fuel cooler. Fuel Cooler The fuel cooler is located behind the rear right hand road wheel. Diesel fuel becomes heated during pressurisation in the high-pressure pump. Ambient heat in the engine bay also contributes to the heating of the fuel returning to the fuel tank. To avoid problems associated with the lower viscosity of high temperature fuel, the returning diesel fuel is diverted into the cooler, if it is over 73ºC (163ºF), by a thermostatic valve.

Low Pressure Pump Electrical Fuel Pump
The electrical fuel pump is located inside the fuel tank in the right-hand side. The electrical fuel pump transports fuel from the swirl pot towards the engine and operates the level control venturis in the left and right sides of the tank. Both venturis deliver fuel to the swirl pot in the right-hand side of the tank. The electrical fuel pump is activated by the ECM via the electrical fuel pump relay In-line Electrical Fuel Pump (Medium Pressure) The in-line electrical fuel pump is located in the inlet line and has the task of providing the HPP with an adequate amount of fuel: • In every operating condition • At the required pressure • Across the entire service life The in-line electrical fuel pump is also activated by the ECM via the same electrical fuel pump relay.

High Pressure Pump High Pressure Pump
The HPP is located at the front left side of the engine, the same position as a distributor-type fuel injection pump. The HPP is the interface between the low-pressure and the high-pressure sections. It has the task of ensuring that there is always enough fuel delivered at a sufficient pressure in every operating mode across the entire service life of the vehicle. This includes the delivery of spare fuel, required for a rapid start and pressure increase in the rail.

High Pressure Pump High Pressure Pump
Fuel is delivered via the filter to the HPP intake and the safety valve (9) situated behind it. It is forced through the throttle bore into a low-pressure duct (8). This duct is connected to the lubrication and cooling circuit of the high-pressure pump. It is therefore not connected to an oil circuit. The drive shaft (1) is driven via the chain drive at three quarters engine speed. It moves the three pump pistons (3) up and down with its eccentric cam (2), depending on the cam shape. If the pressure in the low pressure duct exceeds the opening pressure of the suction valve (6) ( bar), the advance delivery pump can force fuel into the element chamber where the pump piston moves downwards (suction stroke). If the dead-centre point of the pump piston is exceeded, then the intake valve closes. Fuel in the element chamber (4) can no longer escape. It is then compressed in the intake line by the delivery pressure. The accumulating pressure opens the exhaust valve (5) as soon as the pressure in the rail is achieved. Compressed fuel enters the high-pressure system. The pump piston delivers fuel until the upper dead-centre point is reached (delivery stroke). Pressure then falls again, which closes the outlet valve. The remaining fuel is no longer subject to pressure. The pump piston moves downwards. If the pressure in the element chamber falls below the pressure in the low-pressure duct, then the intake valve opens again. The whole process is repeated from the beginning. The high-pressure pump constantly generates the system pressure for the high-pressure rail. The pressure in the rail is determined by the pressure control valve. Since the high-pressure pump is designed for large delivery quantities, there is an excess of compressed fuel when the vehicle is idling or only subject to partial load. Since the compressed fuel is no longer subject to pressure once the excess fuel flows away, the energy generated by the compression is lost and/or heats the fuel. This excess delivered fuel is returned to the tank via the pressure control valve and the fuel cooler. 1. Drive shaft 2. Eccentric cam 3. Pump element with pump piston 4. Element chamber 5. Exhaust valve 6. Suction valve 7. Sealing unit 8. Low pressure duct to pump element 9. Safety valve with throttle bore 10. Ball valve 11. Pressure control valve 12. Inlet 13. Fuel return 14. Pressurised fuel (to the rail) Pump structure (side view)

System Inputs Engine Control Module (ECM)
The ECM has a steel casing to provide protection from electromagnetic radiation and is located in the front passenger side of the plenum. The ECM contains data processors and memory microchips. The output signals to actuators are in the form of earth paths provided by driver circuits contained within the casing. The ECM driver circuits produce heat during normal operation and dissipate this heat via the casing. The airflow around the ECM should not be obstructed. There are regulated voltage outputs to some sensors which use less than 12 volts to avoid voltage drop during engine cranking. The ECM cannot be tested directly, diagnosis must be performed by ensuring that inputs and outputs conform to specifications. TestBook is available for this purpose. If the ECM is to be replaced, the new ECM will be supplied 'blank' and must be configured to the vehicle using TestBook/T4. When the ECM is fitted to the vehicle it must also be synchronised to the immobilisation ECU using TestBook. Engine control modules must not be swapped between vehicles. Inputs and Outputs The ECM is connected to sensors fitted to the engine which allow it to monitor engine operating conditions. The ECM processes these signals and decides the actions necessary to maintain optimum engine performance in terms of driveability, fuel efficiency and exhaust emissions. The memory of the ECM is programmed with instructions for how to control the engine, this is known as the strategy. The memory also contains data in the form of maps which the ECM uses as a basis for fuelling and emission control. By comparing the information from the sensors to the data in the maps, the ECM is able to calculate the various output requirements. The ECM contains an adaptive strategy which updates the system when components vary due to production tolerances or ageing The ECM has an interface of 134 pins via five connectors providing both input information and output control. Not all 134 pins are used.

Crankshaft Position Sensor
Crankshaft Position Sensor (CKP) The CKP sensor is located in the engine block, beneath the starter motor, with its tip adjacent to the outer circumference of the crankshaft reluctor ring. The CKP sensor works on the variable reluctance principle. This uses the disturbance of the magnetic field which is set up around the CKP sensor, caused by the rotation of a reluctor 'target' attached to the crankshaft. The reluctor is a steel ring with 58 'teeth' and a space where two teeth are 'missing'. The teeth, and spaces between, each represent 3º of crankshaft rotation. The two missing teeth provide a reference for angular position. As the reluctor rotates adjacent to the sensor tip, a sinusoidal voltage waveform is produced which can be interpreted by the ECM into crankshaft angular position and velocity. The signal from the CKP sensor is required by the ECM for the following functions: Determine fuel injection timing. Enable the fuel pump relay circuit (after the priming period). Produce an engine speed message for broadcast on the CAN bus for use by other systems. The two pins on the sensor are both outputs. To protect the integrity of the CKP signal the cable incorporates a screen. The cable screen earth path is via the ECM. Correct CKP sensor outputs are dependent upon the air gap between the tip of the CKP sensor and the passing teeth of the reluctor ring. The CKP air gap is not adjustable in this application. In the event of a CKP sensor signal failure any of the following symptoms may be observed: Engine cranks but fails to start. Engine misfires. Engine runs roughly or stalls.

Camshaft Sensor Camshaft Position (CMP) Sensor
The CMP sensor is located on top of the engine on the camshaft cover. This sensor is a Hall effect sensor producing one pulse for every camshaft revolution. The CMP sensor is only used on start up to synchronise the ECM programme with the CKP signal. This is to identify number one cylinder for correct injection timing. Once this has been achieved the input from the CMP sensor is no longer used in any of the ECM strategies. Electrical input to the CMP sensor is supplied via the main relay located in engine compartment fuse box. One output is sensor earth, the other is the signal output to the ECM. In the event of a CMP sensor signal failure the engine will crank but will not start.

Mass Air Flow Sensor Mass Air Flow/ Inlet Air Temperature (MAF/ IAT) Sensor The MAF/ IAT sensor is located on the engine intake air manifold, it combines the two functions into one unit working on the hot film principle. The MAF sensor has two sensing elements contained within a film. One element is at ambient temperature e.g. 25ºC (77ºF) while the other is heated to 200ºC (392ºF) above this temperature e.g. 225ºC (437ºF). As air passes through the MAF sensor it has a cooling effect on the film. The current required to maintain the 200ºC (392ºF) differential provides a precise, although non-linear, signal of the air drawn into the engine. The MAF sensor output is an analogue voltage proportional to the mass of the incoming air. The ECM utilises this data, together with information from the other sensors and the fuelling maps, to determine the correct fuel quantity to be injected into the cylinders. It is also used as a feedback signal for the EGR system. The IAT sensor incorporates a Negative Temperature Coefficient (NTC) thermistor in a voltage divider circuit. As the temperature of the intake air increases, the resistance in the thermistor decreases. As the thermistor allows more current to pass to earth, the voltage sensed at the ECM decreases. The change in voltage is proportional to the temperature change of the intake air. From the voltage output of the sensor, the ECM can correct the fuelling map for intake air temperature. This correction is an important requirement because hot air contains less oxygen than cold air for any given volume. Inputs to the MAF sensor are a 12 volt supply from the engine compartment fuse box and an earth path connection. There are two outputs from the MAF sensor, these are in the form of a signal and signal return connection to the ECM. The IAT sensor utilises a 5 volt reference input from the ECM and shares the earth path of the MAF. The output from the IAT is calculated within the ECM by monitoring the changes in the reference voltage which supplies the IAT voltage divider circuit. The MAF/ IAT sensor connector has gold plated terminals.

Mass Air Flow Sensor Mass Air Flow/ Inlet Air Temperature (MAF/ IAT) Sensor If the MAF sensor fails the ECM implements a back up strategy, which is based on engine speed. In the event of a MAF sensor signal failure any of the following symptoms may be observed: Difficult starting. Engine stalls after starting. Delayed engine response. Emissions control inoperative. Idle speed control inoperative. Reduced engine performance. Should the IAT sensor fail the ECM defaults to an assumed air temperature of -5ºC (23ºF). In the event of an IAT sensor signal failure any of the following symptoms may be observed: Over fuelling resulting in black smoke.

Pedal Demand Sensor Accelerator Pedal Position (APP) Sensor
The APP sensor is located on the pedal box in the driver's footwell. The APP sensor consists of two resistance tracks and two sliding contacts, effectively a pair of potentiometers, connected to the accelerator pedal assembly. The use of a pair of identical sensing elements ensures a position signal is still provided even if one of the sensing elements develops a fault; this is required because there is no mechanical linkage between the accelerator pedal and the ECM. As the accelerator pedal is depressed, the sliding contacts move along the resistance tracks to change the output voltage of the sensor. By monitoring the voltage outputs from the APP, the ECM is able to determine the position, rate of change and direction of movement of the accelerator pedal. It will also store the voltages which correspond with closed 'throttle‘ and wide open 'throttle' and will adapt to new ones in the event of component wear or replacement. The ECM uses the APP voltage to determine closed 'throttle' position to instigate idle speed control, and to enable the overrun fuel reduction strategy. The APP sensor signal is also broadcast on the CAN bus, where it is used by the EAT ECU to determine the correct point for gearshifts and kickdown. The connector and sensor terminals are gold plated for corrosion resistance and temperature stability, care must be exercised when probing the connector and sensor terminals

Pedal Demand Sensor Sensor 1 Sensor 2
Accelerator Pedal Position (APP) Sensor The ECM supplies the APP sensor with a regulated 5 volts supply and an earth path for the resistive tracks. The output signals vary according to the position of the accelerator pedal. The APP sensor earth also acts as a screen to protect the integrity of the signal. If the APP sensor signal fails, the ECM increases the idle speed to 1,250 rev/min, and the engine speed will not increase when the accelerator is depressed. In the event of an APP sensor signal failure, the following symptoms may be observed: No accelerator response. Failure of emission control. Automatic gearbox kickdown inoperative. Volts Sensor 1 Sensor 2 APP Signal

V Engine Coolant Temperature (ECT) Sensor The ECT sensor is located in the engine block at the front of the engine. It provides the ECM with engine coolant temperature information. The ECM uses this ECT information for the following functions: Fuelling calculations. Temperature gauge. To limit engine operation if coolant temperature is too high. Cooling fan operation. Glow plug operating time. The ECM ECT sensor circuit consists of an internal voltage divider circuit incorporating an external negative temperature coefficient thermistor. As temperature rises, the resistance in the thermistor decreases, as temperature decreases, the resistance in the sensor increases. The output of the sensor is the change in voltage as the thermistor allows more current to pass to earth according to the temperature of the coolant. The ECM compares the signal voltage to stored values and compensates fuel delivery to ensure optimum driveability at all times. The engine will require more fuel when it is cold to overcome fuel condensing onto the cold metal surfaces inside the combustion chamber. To achieve a richer air/fuel ratio the ECM extends the injector opening time. As the engine warms up the air/fuel ratio is leaned off. The inputs and outputs for the ECT are a reference voltage and an earth return circuit, both provided by the ECM. The ECT signal is measured at the ECM. Cº

Engine Coolant Temperature (ECT) Sensor In the event of an ECT sensor signal failure any of the following symptoms may be observed: Difficult cold start. Difficult hot start. Driveability concerns. Instrument pack temperature warning illuminated. Temperature gauge reading does not accurately represent the coolant temperature. In the event of ECT signal failure the ECM applies a default value of 80ºC (176ºF) coolant temperature for fuelling purposes. The ECM will also run the cooling fan when the ignition is switched on to protect the engine from overheating. V Cº

Low Pressure Sensor Low Pressure (LP) Fuel Sensor
The LP fuel sensor is located in the fuel filter housing, adjacent to the battery box in the engine compartment. It supplies a signal to the ECM which corresponds with fuel pressure in the fuel filter. The low-pressure fuel sensor is supplied with a 5 volt input signal from the ECM. The ECM also provides an earth connection. Output from the low-pressure fuel sensor is a variable voltage signal dependent upon fuel pressure. This sensors information enables the EDC EMS to reduce the fuel injection quantity at excessively low inlet pressures to the point where engine speed and rail pressure are reduced accordingly. The requisite inlet volume to the high-pressure pump is reduced. This makes it possible for the inlet pressure to the high-pressure pump to rise to the required level. At an inlet pressure of less than 1.7 bar, high-pressure pump damage is possible due to inadequate lubrication. To protect the high-pressure pump, the EMS will shut down the engine if it receives a signal informing it of a low-pressure situation. The engine can be shut down if a differential pressure of less than or equal to 0.5 bar develops between the inlet and the return lines (pump protection). In the event of a low-pressure fuel sensor failure any of the following symptoms may be observed: Engine fails to start. Engine stalls.

High Pressure Sensor Fuel Rail Pressure Sensor (HP)
The fuel rail pressure sensor is located on the end of the fuel rail. A diaphragm located within the sensor is in contact with the pressurised fuel. An electronic resistive element, attached to the diaphragm, distorts as the diaphragm changes in shape due to the pressure exerted by the fuel. The resistance values are converted into an analogue voltage within the pressure sensor and this signal is processed by the ECM. The ECM compares the signal to stored values to calculate current fuel pressure. The fuel rail pressure sensor consists of the following components: Sensor housing with electrical connection. Printed circuit board with electrical evaluation switch. Diaphragm with integrated sensor element. Electrical input to the fuel rail pressure sensor is a 5 volts supply from the ECM. Output is an analogue voltage between volts. In the event of a fuel rail pressure sensor failure any of the following symptoms may be observed: Engine will not start. Severe loss of power. Engine stalls.

Boost Pressure Sensor Pedal Switches
Boost Pressure (BP) Sensor The BP sensor is located on the front side of the intake manifold and has a three pin connector. It provides a voltage signal relative to intake manifold pressure to the ECM. The BP sensor works on the piezo ceramic crystal principal. Piezo ceramic crystals are pressure sensitive and, in the BP sensor, oscillate at a rate dependent on air pressure. The BP sensor produces a voltage between 0 and 5 volts proportional to the pressure level of the air in the intake manifold. A reading of 0 volts indicates low pressure and a reading of 5 volts indicates high pressure. The ECM uses the signal from the BP sensor for the following functions: To maintain manifold boost pressure. To reduce exhaust smoke emissions while driving at high altitude. Control of the EGR system. ECM supplies the BP sensor with a 5 volt power supply. The output from the BP sensor is measured at the ECM. The earth path is supplied via the ECM. In the event of a BP sensor signal failure any of the following symptoms may be observed: Altitude compensation inoperative (engine will produce black smoke). Active boost control inoperative. The ECM assumes a default pressure of 0.9 bar (13 lbf/in 2 ).

Boost Pressure Sensor Pedal Switches
Brake Switch The brake switch is located on the pedal box assembly, it is a Hall effect switch which detects the position of the brake pedal, and therefore when the driver has applied the brakes. The ECM uses the signal from the brake switch for the following: To limit fuelling during braking. To inhibit/ cancel cruise control if the brakes are applied. The brake switch includes two separate circuits, one normally open and one normally closed, connecting to earth. The two circuits are referred to as main brake and brake test. In the event of a brake switch failure any of the following symptoms may be observed: Cruise control will be inactive. Increased fuel consumption. Clutch Pedal Switch The clutch switch is a Hall effect device and is located on the pedal box assembly. The clutch switch is activated when the clutch pedal is operated. The ECM uses the signal from the clutch switch for the following functions: To provide surge damping during gear changes. To inhibit/ cancel cruise control if the clutch pedal is pressed. Surge damping stops engine speed rising dramatically during gear changes. Surge damping assists driveability in the following ways: Smoother gear changes. Greater exhaust gas emission control. Improved fuel consumption. The clutch switch receives a 12 volts reference voltage from the ECM. With the clutch pedal in the rest position the switch is connected to earth. When the clutch pedal is pressed the ECM receives a 12 volt signal. In the event of a clutch pedal switch failure any of the following symptoms may be observed: Surge damping will be inactive Cruise control will be inactive Switch Condition Brake Switch Circuit Main Switch Circuit Brake not pressed Open circuit Earth Brake pressed Battery positive 6 to 8 volts

Immobilisation (EWS3) Immobilisation System
The ECM plays a major role in the immobilisation of the vehicle. The ECM inhibits engine fuelling until the ECM receives a valid coded signal from the immobilisation ECU. The coded signal from the immobilisation ECU comes in the form of a rolling code. This code cannot be copied or bypassed in any way. When new, the immobilisation ECU is blank and is programmed with a starting code known as a 'seed'. The seed is then used as a base point for the rolling code when the immobilisation ECU is synchronised to the ECM during manufacture. Once synchronised, the ECM and immobilisation ECU are not interchangeable and work as a matching pair. When a new ECM is fitted to a vehicle during service, the new ECM must be in a blank condition. The blank ECM must be re-synchronised to the immobilisation ECU using TestBook/T4. When a new immobilisation ECU is fitted to a vehicle during service, the new immobilisation ECU must be supplied with a seed that matches the vehicle. This information is held by Rover. The rolling codes in the new immobilisation ECU and the existing ECM must then be synchronised using TestBook/T4. The immobilisation ECU receives engine speed information from the ECM to inhibit starter motor operation when the engine is running, to prevent damage to the starter drive pinion and ring-gear. Engine speed information is broadcast on the CAN bus by the ECM. The instrument pack converts and broadcasts the engine speed signal on the K bus where it is received by the immobilisation ECU.

Automatic Gearbox Electronic Automatic Transmission (EAT) ECU Strategy
On automatic gearbox models, the EAT ECU implements an idle neutral strategy, which is part of the fuel reduction strategy. Neutral is selected, reducing engine load and fuel consumption, when all of the following conditions are met: ECM confirms engine at idle. 'D' selected on gear selector lever. Foot brake applied. Should one of these conditions change, after neutral has been selected, 'D' will be reselected automatically. When the EAT ECU requests, via the CAN bus, a reduction in engine torque, the ECM reduces engine torque by cutting back fuel delivery. This ensures smooth gear changes throughout the engine speed and load ranges, and reduces exhaust emissions. Information sent from the ECM to the EAT ECU using the CAN bus is as follows: Accelerator pedal position. Engine torque. Engine speed. Coolant temperature. Ignition key position. Virtual 'throttle' angle.

Automatic Gearbox Electronic Automatic Transmission (EAT) ECU Strategy
Information sent from the EAT ECU to the ECM using the CAN bus is as follows: Torque reduction requests. Gear lever position. Current gear. Gear change in progress. Additional cooling request.

System Outputs General
The ECM controls the operation of the engine using information stored within memory in the form of maps. The maps contain data which is used to determine the most efficient fuelling for any given driving condition. The ECM also has maps for the operation of sub systems such as EGR. The ECM is an adaptive unit which 'learns' the characteristics of the vehicle components. This feature allows the ECM to compensate for any variations in components fitted to the vehicle in production, and to adapt to changes which may occur in service. The ability to compensate for 'wear and tear' and environmental changes during the life of the vehicle ensures that the ECM can comply with the emission control legislation over extended periods. The ECM is programmed with a 'strategy', this controls the decisions about 'when' to turn specific functions on and off. The inputs to this decision making process are supplied by sensors, mounted at various locations on the vehicle, which supply information to the ECM. If a sensor fails to supply information, the ECM will use the remaining sensors, and insert a default value for the missing information. This is not always possible, in which case the vehicle will be disabled. Where a default is used, this may result in reduced driveability, or an increase in fuel consumption and exhaust emissions. The ECM is programmed with vehicle specific information known as a 'calibration', this is the data required to calculate the 'outputs'. This information along with sensor inputs and interfaced data determines actuator output signals. The ECM facilitates strategies such as: Smoke limitation. Active surge damping. Automatic gear change. Fuel reduction. Engine cooling. Combustion noise limitation.

System Outputs General
During idle and wide open 'throttle' conditions the ECM uses mapped information to respond to the input from the APP sensor. To implement the optimum fuelling strategy for idle and wide open throttle the ECM requires input information from the following: CKP sensor. APP sensor. ECT sensor. MAF/ IAT sensor. High pressure fuel sensor. This information is then compared to mapped information within the ECM to facilitate acceleration using the following actuators and controllers: EGR modulator - closed for cleaner combustion. Fuel pressure regulator - increase fuel pressure to injector rail. Electronic fuel injectors - injection duration longer. A/C compressor clutch relay - de-energised during wide-open 'throttle' to reduce engine load. EAT ECU - kickdown (automatic gearbox models). During cold start conditions the ECM uses ECT information to determine if cold start strategy is required. During cold start conditions the ECM will inject more fuel into the cylinders and will initiate glow plug timing strategy for effective cold starting. Normal fuel strategy is used during hot starts.

Outputs Fuel Pump Relay Main Relay Air Con Relay Cooling Fan Relay
The fuel pump relay is located in the passenger compartment fusebox. It is a 4 pin, normally open relay. The ECM controls the earth path to the relay winding. When energised, the relay supplies power to the primary and secondary low pressure fuel pumps. When the ignition is switched on the fuel pump relay is activated by the ECM, pressurising the fuel to 2.5 bar (36 lbf/in 2 ). The ECM then deactivates the relay after approximately 1 minute. If the ignition is turned on, and the engine started, the ECM will energise the relay continuously. The input supply for the relay windings is battery voltage, the earth path for the winding is from the ECM driver circuit. The input supply for the switching contacts comes from the engine compartment fuse box. The output from the contacts is direct to the primary low-pressure fuel pump motor located within the fuel tank, and the secondary low-pressure fuel pump located near the vehicle battery tray. In the event of a fuel pump relay failure any of the following symptoms may be observed: Engine stalls or will not start. No fuel pressure at the fuel rail.

Outputs Fuel Pump Relay Main Relay Air Con Relays Main Relay
The main relay is located in the engine compartment fusebox. The relay controls the voltage supplies to the main peripheral components of the system under the control of the ECM. The ECM has a feed which allows it to become active when it receives an input from the ignition switch position II (ignition on). The ECM will then energise the main relay. The main relay is a standard normally open 4 pin relay. The main relay contact supplies battery voltage to the following components: ECM. MAF/ IAT sensor. CMP sensor. Fuel pressure regulator. EGR modulator. Glow plug ECU. Voltage input to the relay winding and the contacts comes from the vehicle battery. When the main relay is energised, the switching contact closes and power is supplied to various components on the vehicle. The earth path for the main relay winding is supplied by the ECM. When the earth path is completed, the main relay energises. In the event of a main relay failure any of the following symptoms may be observed: Engine will crank but not start. The engine will stop if the relay fails. Air Conditioning (A/C) The A/C system is dependent on the ECM for actuation of the compressor clutch. While the engine is running, the ECM receives a compressor on/off request on the CAN bus every 10 seconds, and each time that the A/C is turned on or off. When the request is for the compressor to be turned on, the ECM will engage the compressor clutch providing the following conditions exist: All engine sensors are functioning. The engine is not under heavy load (i.e. accelerator pedal is not fully down). The coolant temperature is not more than 118 ?C (244 ?F). Evaporator temperature not less than -7 ?C (25 ?F). Engine speed over 500 rev/min. A/C refrigerant pressure within the specifications required by the trinary switch. The ECM engages the compressor clutch by providing an earth path for the A/C compressor clutch relay winding. The contacts in the relay close and supply a 12 volt feed to engage the compressor clutch. When the compressor clutch request has been granted a confirmation message is broadcast on the CAN bus. If any of the conditions necessary to engage the compressor clutch cease to exist, the ECM will disengage the compressor. The ECM broadcasts a confirmation that the A/C clutch has been disengaged on the CAN bus. Fuel Pump Relay Main Relay Air Con Relays

Outputs Fuel Pump Relay Main Relay Air Con Relay Cooling Fan Relay
Cooling Strategy The ECM controls cooling fan operation for the engine, automatic gearbox and A/C condenser. With the ECM controlling cooling fan operation, it can adjust injection duration and timing to compensate for additional engine load imposed by the alternator during cooling fan operation. The ECM can request one of three fan speeds depending on coolant temperature, EAT ECU and A/C requests. These fan speeds are: Low: 250 rev/min. Medium: 800 rev/min. High: 1750 rev/min. Priority will be given to the highest fan speed request. When A/C is requested, fan speed is set to low, unless the EAT ECU or ECT requires a higher fan speed. If the cooling request circuit of the trinary switch is open the fan speed is then set to medium. High speed fan operation will be selected by one of the following conditions: Engine temperature is greater than 119 ?C (246 ?F). EAT ECU request for increased cooling. The ECM achieves fan speeds by sending a 140 Hz PWM signal to a PWM converter located within the fan relay module. The PWM converter is connected to three relays, also located within the fan relay module, and determines which relays to energise by the duty cycle of the pulse: 13%: Relay one energised to give low fan speed. 40%: Relays one and two energised to give medium fan speed. 86%: Relays one, two and three energised to give high fan speed. Fuel Pump Relay Main Relay Air Con Relay Cooling Fan Relay

Fuel Pressure Regulator
Fuel Pressure Regulator Valve The pressure regulator valve is mounted on the high-pressure pump and controls the fuel pressure within the fuel rail. It is an electrically operated solenoid valve controlled by the ECM with only two states, open and closed. When de-energised, the valve is opened by a spring, diverting fuel to the return line. This decreases the fuel pressure in the fuel rail. In this state fuel rail pressure is approximately 100 bar (1450 lbf/in2 ). When energised, the valve is closed, allowing maximum fuel pressure in the fuel rail. This pressure can reach approximately 1300 bar (18,854 lbf/in2 ). The ECM controls the fuel rail pressure by operating the pressure regulator valve with a pulse width modulated signal. The longer the opening time (duty cycle) of the valve, the lower the pressure in the fuel rail. The shorter the opening time (duty cycle) of the valve, the higher the pressure in the fuel rail. The pressure regulator receives a PWM signal of 0-12 volts from the ECM. ECM actuation of the pressure regulator is determined by the following: Fuel rail pressure. Engine load. Accelerator pedal position. Engine temperature. Engine speed. In the event of a pressure regulator failure, any of the following symptoms may be observed: Engine will not start. Severe loss of power. Engine stalls.

Glow Plug ECU Glow Plug ECU and Glow Plugs
The glow plug ECU is located next to the ECM in the plenum. The ECM controls all glow plug operations via the glow plug ECU. The glow plug warning lamp is controlled by the ECM from information received from the glow plug ECU. The 4 glow plugs are located in the cylinder head on the inlet side. The glow plugs form a vital part of the engine starting strategy. The glow plugs heat the air inside the cylinder during cold starts to assist combustion. The use of glow plugs helps to reduce the amount of extra fuel required on start up, the main cause of black smoke. It also requires less injection advance, which reduces engine noise, particularly when idling with a cold engine. The main part of the glow plug is a tubular heating element that protrudes into the combustion chamber of the engine. The heating element contains a spiral filament encased in magnesium oxide powder. At the tip of the tubular heating element is the heater coil. Behind the heater coil, and connected in series, is a control coil. The control coil regulates the heater coil to ensure that it does not overheat.

Glow Plug Pre-heat Seconds Degrees Celsius
Glow Plug ECU and Glow Plugs Pre-heat is the length of time the glow plugs operate prior to engine cranking. The ECM controls the pre-heat time of the glow plugs based on battery voltage and coolant temperature information. Post-heat is the length of time the glow plugs operate after the engine starts. The ECM controls the post-heat time based on ECT information. If the ECT fails, the ECM will operate pre-heat and post-heat time strategies with default values from its memory. The engine will be difficult to start. The glow plug ECU is supplied with power directly from the vehicle battery, an earth connection directly to the vehicle body from the glow plug ECU is used. The glow plug ECU also receives a voltage signal from the main relay to indicate ignition switch operation. Input information relating to engine temperature and time base calculations comes from the ECM. The glow plug ECU is able to process this information and then supply output control to the glow plugs in the engine. In the event of a glow plug failure any of the following symptoms may be observed: Difficult starting. Excessive smoke emissions after engine start. Seconds Seconds Degrees Celsius Degrees Celsius Pre Heat Seconds Degrees Celsius Post Heat

Injectors Injectors A. Injector Closed (at Rest) B. Injector Open (Injection) 1. Fuel return 2. Electrical connection 3. Activation unit (solenoid valve) 4. High pressure fuel supply 5. Valve control chamber 6. Valve ball 7. Inlet port 8. Outlet port 9. Valve control piston 10. Supply channel to nozzle 11. Nozzle needle

Injectors Injectors Referring to the picture, the high-pressure connection (4) guides the fuel through a channel (10) to the nozzle and also through the supply throttle (7) in the control chamber (5). The control chamber is connected to the fuel return line (1) by the outlet throttle (8), which is opened by a solenoid valve. When the outlet throttle is closed, hydraulic force on the valve piston (9) exceeds that on the pressure stage of the injector needle (11). Consequently, the injector needle is pressed into its seat and seals the high-pressure channel off from the engine compartment. Fuel cannot enter the combustion chamber, although it is constantly pressurized at the high-pressure connection. When the injector activation unit is actuated (solenoid valve), the outlet throttle is opened. This reduces the pressure in the control chamber, and therefore the hydraulic force on the valve piston. As soon as the hydraulic force drops below that on the pressure stage of the injector needle, the injector needle opens, which allows the fuel to enter the combustion chamber through the spray apertures. This indirect activation of the injector needle via a hydraulic force increasing system is used because the force required to open the injector needle using the solenoid valve cannot be produced directly. The control quantity required in addition to fuel quantity injected enters the fuel return line via the control chamber throttle. In addition to the control quantity, fuel is also lost at the throttle needle and valve piston guide (leakage quantity). The function of the injector can be sub-divided into four operating statuses when the engine is running and the high-pressure pump is delivering fuel: Injector closed (under high pressure) Injector opens (start of injection) Injector fully open Injector closes (end of injection) These operating statuses are applied according to the distribution of force amongst the components of the injectors. If the engine is not running, the nozzle spring closes the injector.

Injectors Closed Injector Closed
When at rest, the solenoid valve is not activated and is therefore closed. Because the outlet throttle is closed, the armature ball is pressed into the lodgment at the drain throttle by the valve spring. The rail high pressure accumulates in the valve control chamber. The same pressure is also exerted in the chamber volume of the nozzle. The forces applied by the pressure to the surfaces of the control piston and the force of the nozzle spring keeps the injector needle closed against the opening force attacking its pressure stage.

Injectors Open Injector Opens (Start of Injection)
The injector is at rest. The solenoid valve is activated by the starting current of 20 amps, which enables the solenoid valve to be opened quickly. The force of the activated electromagnet exceeds that of the valve spring and the armature opens the final throttle. After a maximum of 450 ms, the increased starting current of 20 amps is reduced to a lower retaining current of 12 amps from the electromagnet. This is possible because the air gap of the magnetic circuit is now smaller. Opening the drain throttle allows fuel to flow out of the valve control chamber into the cavity above, and then to the fuel tank via the fuel return line. The inlet port prevents complete compensation from taking place and the pressure in the valve control chamber drops. As a consequence, the pressure in the valve control chamber is lower than the pressure in the chamber volume of the nozzle which still has the same level of pressure as the rail. The reduced pressure in the valve control chamber leads to less pressure being exerted on the control piston and to the injector needle being opened. Injection Commences. The speed at which the injector needle opens is determined by the difference in through put in the inlet and outlet throttle. After a stroke of approx. 200 mm, the control piston reaches its upper limit point and stays there, supported by a cushion of fuel. This cushion is the result of the stream of fuel created between the inlet and outlet throttle. The injector nozzle is now completely open and the fuel is injected into the combustion chamber at a pressure approaching that of the pressure in the rail.

Injectors Injector Closes (End of Injection)
If the solenoid valve is no longer activated, then the armature is forced downwards by the force of the valve spring. The ball then closes the outlet port. To prevent excessive wear from the contact between the ball and the valve’s lodgment, the armature consists of two parts. Although the armature plate is guided downwards by a cam, it can also oscillate downwards by means of a reset spring, there by preventing the armature and ball from being subject to any downward forces. As in the rail, closing the outlet port causes pressure to accumulate in the control compartment through the inlet of the inlet port. This increased pressure exerts greater force on the surface at the head end of the control piston. This force from the valve control chamber and the spring force exceed the force from the chamber volume, the injector needle closes. The speed at which the injector needle closes is determined by the through put of the inlet port. Injection stops once the nozzle needle reaches its lower limit point.

Exhaust Gas Recirculation
Exhaust Gas Recirculation (EGR) The EGR modulator is located on the front of the engine at the side of the starter motor. The EGR modulator is a solenoid operated valve which regulates the vacuum source to the EGR valve, causing it to open or close. The ECM utilises the EGR modulator to control the amount of exhaust gas being recirculated in order to reduce exhaust emissions and combustion noise. EGR is enabled when the engine is at normal operating temperature and under cruising conditions. The EGR modulator receives battery voltage from the main relay in the engine compartment fusebox. The ECM completes the earth path to the solenoid winding. The ECM controls the EGR valve operation using a PWM signal. The duty cycle of the solenoid determines the amount of vacuum supplied to the EGR valve and, therefore, the volume of exhaust gas allowed to enter the cylinders. In the event of an EGR modulator failure the EGR system will become inoperative.

Cruise Control Component Layout
The cruise control system is integrated with the engine management system and uses fuelling intervention to automatically maintain a set vehicle speed. Once engaged, the system can also be used to accelerate the vehicle without using the accelerator pedal. The cruise control system consists of: A master switch. SET+ and RES– steering wheel switches. A clutch switch (manual gearbox models). An interface ECU. A warning lamp. The system also uses: Inputs from the brake switch and the Anti-lock Braking System (ABS) ECU/modulator. The Engine Control Module (ECM). Cruise control is enabled when the master switch is pressed. Once enabled, the cruise control system is operated using the steering wheel switches. The steering wheel switches output signals to the interface ECU, which then signals the ECM. In the cruise control mode, the ECM adjusts the pulse width of the fuel injector signals to adjust the fuel supply as necessary to maintain the vehicle at the set speed. The cruise control warning lamp provides a visual indication of when the system is engaged.

Cruise Control Control Diagram
Master Switch The master switch controls an ignition feed to the interface ECU to enable the system. The switch is an electrically latching push switch installed in the centre console switch panel. A green LED in the switch remains illuminated while the switch is latched. Steering Wheel Switches The steering wheel switches, SET+ and RES–, are non latching push switches that engage and disengage cruise control and adjust the set speed. While pressed, the switches connect a power supply to the interface ECU. Clutch Switch (Manual Gearbox Models) The clutch switch is a Hall effect sensor that produces a pedal status output to the ECM. Located in the pedal mounting bracket, the clutch switch is activated by a tang on the clutch pedal. The clutch switch consists of an inner sensor in an outer mounting sleeve. To ensure correct orientation, the sensor is keyed to the mounting sleeve and the mounting sleeve is keyed to the mounting bracket. Mating serrations hold the sensor in position in the mounting sleeve. While the clutch pedal is released, the tang rests against end of the sensor. When the clutch pedal is pressed, the tang moves away from the sensor and induces a change of output voltage.

Cruise control Interface ECU
The interface ECU converts the analogue signals from the steering wheel switches into serial data messages, known as Multi-Function Logic (MFL) messages, which can be interpreted by the ECM. It also controls the output of a cruise engaged power supply to the instrument pack and, where applicable, the Electronic Automatic Transmission (EAT) ECU. The interface ECU is installed in the front passenger footwell area, behind the fascia. MFL Messages An ignition power supply from the master switch activates the interface ECU, which then monitors the inputs from the steering wheel switches and the cruise control status message from the CAN bus. From these, the interface ECU determines which of three messages, RESUME, SET or OFF, to output as the MFL message. Each time the interface ECU is activated, the output of the RESUME message is automatically inhibited until after the first engagement of cruise control. Cruise Engaged Power Supply When cruise control is engaged, the interface ECU outputs the power supply to the instrument pack and, where applicable, the EAT ECU. The instrument pack uses the power supply to operate the cruise control warning lamp. The EAT ECU uses the power supply to switch between normal and cruise control modes of operation. Warning Lamp The warning lamp indicates the status of the cruise control system. Located in the instrument pack, the warning lamp consists of a motorway graphic on a yellow background that illuminates when cruise control is engaged. Operation When the master switch is pressed, the interface ECU is enabled and monitors the inputs from the steering wheel switches and the CAN bus. The ECM is in the normal fuelling mode and outputs the cruise control inactive message on the CAN bus. Engagement Cruise control is engaged by pressing the SET+ steering wheel switch. On receipt of the input from the SET+ switch, the interface ECU outputs the MFL SET message to the ECM. Provided the vehicle is in the correct driving configuration, the ECM then stores the current vehicle speed in memory as the set speed, adjusts the fuel delivery from the injectors as necessary to maintain the vehicle at the set speed, and changes the cruise control CAN bus message to active. The vehicle is in the correct driving configuration, when: The brakes are off. The clutch is engaged (manual gearbox models). Moving at a road speed between 22 and 125 mph (35 and 200 km/h). Where applicable, traction control is not active. When the interface ECU outputs the MFL SET message, it also outputs the power supply to the instrument pack and, where applicable, the EAT ECU. On receipt of the power supply: The instrument pack illuminates the cruise control warning lamp, to indicate that cruise control is engaged The EAT ECU adopts the cruise control mode, which uses a shift map less sensitive to changes of 'throttle‘ opening to prevent unnecessary gear shifts. This improves operating refinement for a minor loss of performance.

Cruise control Cruise Control Acceleration
While cruise control is engaged, the vehicle can be accelerated using either the SET+ switch or the accelerator pedal. A momentary press (less than 0.5 second) of the SET+ switch increments the set speed by 1 mph (1.6 km/h) and the vehicle accelerates to the new set speed; pressing and holding the SET+ switch causes the vehicle to accelerate until the switch is released, at which point the increased vehicle speed is adopted as the new set speed. If the accelerator pedal is used to accelerate the vehicle, cruise control remains engaged and the set speed is resumed once the accelerator pedal is released or, if the SET+ switch is pressed before the accelerator pedal is released, the higher speed is adopted as the new set speed. Suspend/Resume Cruise control can be manually suspended and resumed (at the previous set speed) using the RES– steering wheel switch. The system automatically suspends cruise control if one of the conditions required to enable the system is no longer present, e.g. the brakes are applied. Cruise control is also automatically suspended if the vehicle speed increases to more than 10 mph (16 km/h) above the set speed for more than 30 seconds, e.g. when travelling downhill or using the accelerator pedal to override cruise control. Suspend When the RES– switch is pressed, the interface ECU outputs the MFL OFF message, and the ECM resumes normal fuelling control and outputs the cruise control inactive message on the CAN bus. When cruise control is suspended: Fuel delivery from the injectors is decreased to the engine idle speed range. The set speed is retained in memory by the ECM. The cruise control warning lamp is extinguished. On automatic gearbox models, the EAT ECU returns to its previous operating mode. Resume When cruise control is suspended and the RES– switch is pressed, the interface ECU outputs the MFL RESUME message. Provided the inputs to the ECM indicate that the vehicle is in the correct driving configuration, the ECM engages cruise control at the previous set speed and changes the CAN bus cruise control message to active. Cancelling Cruise control is cancelled by pressing the master switch or turning the ignition switch to 0. When cruise control is cancelled, the set speed is deleted from the memory of the ECM and the LED in the master switch extinguishes. When cruise control is cancelled:

Cruise Control Diagnostics
While the system is active, the ECM monitors the cruise control inputs it receives. If a fault is detected, a related fault code is stored in the non volatile memory of the ECM and cruise control is cancelled for the remainder of the ignition cycle. Diagnostic fault information can be accessed using TestBook, which communicates with the ECM via an ISO K line from the diagnostic socket. The interface ECU monitors the CAN bus and, if it detects a fault, modifies the MFL signal to alert the ECM to cancel cruise control. The system is reset at the beginning of each ignition cycle and operates normally if a previously detected fault is no longer present. Cruise Control

Testbook Real Time Display
Notes:

Engine Roughness Notes

Engine Roughness Fuel Correction
Notes

Pedal Demand Sensors Notes

Cruise Control Notes

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