Electronic Engine Controls (4.4L): Other Land Rover Range Rover III facelift

GENERAL

The V8 4.4 Liter engine is controlled by an engine control module (ECM) manufactured by DENSO. The Engine Management System (EMS) controls the following

1. Engine fueling
2. Ignition timing
3. Closed loop fueling
4. Knock control
5. Idle speed control
6. Emission control
7. On Board Diagnostic
8. Interface with the immobilization system
9. Speed control

The engine control module (ECM) controls the engine fueling by providing sequential fuel injection to all cylinders. Ignition is controlled by a direct ignition system, provided by eight plug top coils. The engine control module (ECM) is able to detect and correct for ignition knock on each cylinder and adjust the ignition timing for each cylinder to achieve optimum performance.

The engine control module (ECM) uses a torque-based strategy to generate the torque required by the driver and other vehicle control modules. The EMS uses various sensors to determine the torque required from the engine. The EMS also interfaces with other vehicle electronic control modules's, via the controller area network (CAN) bus, to obtain additional information (e.g. road speed from the anti-lock brake system (ABS) control module). The EMS processes these signals and decides how much torque to generate. Torque is then generated by using various actuators to supply air, fuel and spark to the engine (electronic throttle, injectors, coils, etc.).

Scheme 41

The engine control module (ECM) is located in the E-Box on the right-hand (RH) side of the engine compartment at the front.

System engine control module (ECM) has the following inputs

1. restraints control module (RCM)
2. Park Neutral position switch
3. Ignition coil feedback
4. Fuel rail temperature
5. Mass air flow/intake air temperature
6. Engine speed
7. Intake cam position
8. Driver demand
9. Brake pedal switch
10. Generator load
11. UHEGO
12. HEGO
13. Throttle position
14. Cooling fan speed
15. Ignition switch position
16. Knock sensors
17. manifold absolute pressure (MAP) sensor
18. Coolant temperature
19. Engine oil temperature

The engine control module (ECM) outputs to the following

1. Throttle Actuator
2. Brake vacuum pump relay
3. Ignition coils (x8)
4. Oxygen sensor heaters (4)
5. Fuel injectors (8)
6. exhaust gas recirculation (EGR) valve
7. Variable Valve Timing Oil Valves (2)
8. Purge valve
9. Engine cooling fan
10. Fuel pump relay
11. Starter relay
12. EMS main relay
13. Generator control
14. Diagnostic Module Tank Leakage (DMTL) (NAS Only)
15. E-box fan

CRANKSHAFT POSITION SENSOR (CKP)

The crankshaft position sensor is mounted at the rear underside of the engine near the transmission bell housing. Connection between the sensor and the harness is via a link harness and a two-way connector. Both wires go directly to the engine control module (ECM). The sensor produces the signal which enables the engine control module (ECM) to determine the angle of the crankshaft, and the engine rpm. From this, the point of ignition, fuel injection, etc. is calculated. If the signal wires are reversed a 3° advance in timing will occur, as the electronics within the engine control module (ECM) uses the falling edge of the signal waveform as its reference/timing point for each tooth.

The reluctor is pressed into the flywheel and has a "tooth" pattern based on 36 teeth at 10° intervals and approximately 5° wide: one of the teeth is removed to provide a hardware reference mark which is 60 degrees before top dead center (BTDC) No. 1 cylinder. Because of the crankshaft sensor's orientation, the target wheel uses windows machined into the face, rather than actual teeth.

The sensor operates by generating an output voltage caused by the change in magnetic field that occurs as the windows pass in front of the sensor. The output voltage varies with the speed of the windows passing the sensor, the higher the engine speed, the higher the output voltage. Note that the output is also dependent on the air gap between the sensor and the teeth (the larger the gap, the weaker the signal, the lower the output voltage). The engine control module (ECM) transmits the engine speed to other vehicle control modules on controller area network (CAN).

CAMSHAFT POSITION SENSOR (CMP)

Two sensors are located at the rear of the engine, in the cylinder head (one per bank), above the rear cylinders. This is a Variable Reluctor Sensor (VRS) producing four pulses for every two engine revolutions. The sensing element is positioned between 0 and 2mm from the side of the cam gear wheel.

The variable cam intake is parked in the retarded position and can advance up to 48 degrees.

The camshaft timing wheel is a sintered component which has four teeth on it to enable the EMS to detect cylinder identification. The signal is used for

1. Variable intake cam timing
2. Cylinder recognition
3. Enabling sequential fuel injection
4. Knock control
5. Cylinder identification for diagnostic purposes.

Failure symptoms include

1. Ignition timing reverting to the base mapping, with no cylinder correction.
2. Active knock control is disabled, along with its diagnostic (safe ignition map-loss of performance).
3. Quick cam/crank synchronization on start disabled.
4. Variable cam timing is disabled

ENGINE COOLANT TEMPERATURE SENSOR (ECT)

The sensor is located at the front of the engine in the water pipe below the throttle body. The engine coolant temperature (ECT) sensor is a thermistor used to monitor the engine coolant temperature. The engine coolant temperature sensor is vital to the correct running of the engine as a richer mixture is required at lower block temperatures for good quality starts and smooth running, leaning off as the temperature rises to maintain emissions and performance.

The sensor has an operating temperature range of -40 Degrees Celsius to 119 Degrees Celsius. When a defective coolant sensor is detected, the engine control module (ECM) uses the oil temperature sensor value.

PURGE VALVE

The purge valve is located at the rear of the engine on a bracket which is attached to the transmission bell housing. The purge valve is a solenoid operated valve which is closed when de-energized. The purge valve is controlled by a 10Hz pulse width modulation (PWM) signal from the engine control module (ECM). When the engine operating conditions are correct, the engine control module (ECM) opens the purge valve which causes fuel vapor and fresh air to be drawn through the charcoal canister. The fresh air is drawn through the charcoal canister via the DMTL pump fresh air vent. Refer to Evaporative Emissions .

ENGINE OIL TEMPERATURE SENSOR

Oil temperature is monitored through a temperature sensor mounted in the oil system. This component is a negative temperature coefficient (NTC). The sensor is mounted next to the oil pressure sensor at the front of the engine and locates into the oil filter bracket.

FUEL RAIL TEMPERATURE SENSOR

The fuel rail temperature sensor measures the temperature of the fuel in the fuel rail. This input is then used to deliver the correct quantity of fuel to the engine. Operating Range -40 Degrees Celsius to 150 Degrees Celsius. The fuel rail temperature sensor is fitted on the rear of the right hand bank (bank A) fuel rail.

MASS AIR FLOW/INLET AIR TEMPERATURE SENSOR (MAF/IAT)

The air flow meter is located in the clean air duct immediately after the air filter box.

The air mass flow is determined by the cooling effect of intake air passing over a "hot film" element contained within the device. The higher the air flow the greater the cooling effect and the lower the electrical resistance of the "hot film" element. The engine control module (ECM) then uses this signal from the Mass Air Flow meter to calculate the air mass flowing into the engine.

The measured air mass flow is used in determining the fuel quantity to be injected in order to maintain the stoichiometric air/fuel mixture required for correct operation of the engine and exhaust catalysts. Should the device fail there is a software backup strategy that will be evoked once a fault has been diagnosed.

The following symptoms may be observed if the sensor fails

1. During driving the engine RPM might dip, before recovering.
2. Difficulty in starting or start-stall.
3. Poor throttle response/engine performance.
4. Lambda control and idle speed control halted.
5. Emissions incorrect.
6. AFM signal offset

The intake air temperature (IAT) sensor is integrated into the mass air flow (MAF) sensor. It is a temperature dependent resistor (thermistor), i.e. the resistance of the sensor varies with temperature. This thermistor is a negative temperature coefficient (NTC) type element meaning that the sensor resistance decreases as the sensor temperature increases. The sensor forms part of a voltage divider chain with an additional resistor in the engine control module (ECM). The voltage from this sensor changes as the sensor resistance changes, thus relating the air temperature to the voltage measured by the engine control module (ECM).

The engine control module (ECM) stores a 25 Degrees Celsius default value for air temperature in the event of a sensor failure.

MANIFOLD ABSOLUTE PRESSURE SENSOR (MAP)

The manifold absolute pressure (MAP) sensor provides a voltage proportional to the absolute pressure in the intake manifold. This signal allows the load on the engine to be calculated and used within the internal calculations of the engine control module (ECM). The sensor is located on the rear of the air intake manifold.

The output signal from the manifold absolute pressure (MAP) sensor, together with the crankshaft position (CKP) and intake air temperature (IAT) sensors, is used by the engine control module (ECM) to calculate the amount of air induced into the cylinders. This enables the engine control module (ECM) to determine ignition timing and fuel injection duration values.

The manifold absolute pressure (MAP) sensor receives a 5V supply voltage from pin 48 of engine control module (ECM) connector C0634 and provides an analogue signal to pin 69 of engine control module (ECM) connector C0634, which relates to the absolute manifold pressure and allows the engine control module (ECM) to calculate engine load. The engine control module (ECM) provides a ground for the sensor via pin 11 of engine control module (ECM) connector C0634.

If the manifold absolute pressure (MAP) signal is missing, the engine control module (ECM) will substitute a default manifold pressure reading based on crankshaft speed and throttle angle. The engine will continue to run with reduced driveability and increased emissions, although this may not be immediately apparent to the driver. The engine control module (ECM) will store fault codes which can be retrieved using T4.

KNOCK SENSORS

The V8 EMS has two knock sensors located in the V of the engine, one per cylinder bank. The sensors are connected to the engine control module (ECM) via a twisted pair.

The knock sensors produce a voltage signal in proportion to the amount of mechanical vibration generated at each ignition point. Each sensor monitors the related cylinder bank.

The knock sensors incorporate a piezo-ceramic crystal. This crystal produces a voltage whenever an outside force tries to deflect it, (i.e. exerts a mechanical load on it). When the engine is running, the compression waves in the material of the cylinder block, caused by the combustion of the fuel/air mixture within the cylinders, deflect the crystal and produce an output voltage signal. The signals are supplied to the engine control module (ECM), which compares them with `mapped' signals stored in memory. From this, the engine control module (ECM) can determine when detonation occurs on individual cylinders. When detonation is detected, the engine control module (ECM) retards the ignition timing on that cylinder for a number of engine cycles, then gradually returns it to the original setting.

Care must be taken at all times to avoid damaging the knock sensors, but particularly during removal and fitting procedures. The recommendations regarding torque and surface preparation must be adhered to. The torque applied to the sensor and the quality of the surface preparation both have an influence over the transfer of mechanical noise from the cylinder block to the crystal.

The engine control module (ECM) uses the signals supplied by the knock sensors, in conjunction with the signal it receives from the camshaft sensor, to determine the optimum ignition point for each cylinder. The ignition point is set according to preprogrammed ignition maps stored within the engine control module (ECM). The engine control module (ECM) is programmed to use ignition maps for 98 RON premium specification fuel. It will also function on 91 RON regular specification fuel and learn new adaptions. If the only fuel available is of poor quality, or the customer switches to a lower grade of fuel after using a high grade for a period of time, the engine may suffer slight pre-ignition for a short period. This amount of pre-ignition will not damage the engine. This situation will be evident while the engine control module (ECM) learns and then modifies its internal mapping to compensate for the variation in fuel quality. This feature is called adaption. The engine control module (ECM) has the capability of adapting its fuel and ignition control outputs in response to several sensor inputs.

The engine control module (ECM) will cancel closed loop control of the ignition system if the signal received from either knock sensor becomes implausible. In these circumstances the engine control module (ECM) will default to a safe ignition map. This measure ensures the engine will not become damaged if low quality fuel is used. The MIL lamp will not illuminate, although the driver may notice that the engine 'pinks' in some driving conditions and displays a drop in performance and smoothness.

When a knock sensor fault is stored, the engine control module (ECM) will also store details of the engine speed, engine load and the coolant temperature.

ELECTRONIC THROTTLE

The V8 EMS incorporates an electric throttle control system. The electronic throttle body is located on the air intake manifold in the engine compartment. The system comprises three main components

1. Electronic throttle control valve
2. Accelerator pedal position (APP)
3. Engine control module (ECM)

When the accelerator pedal is depressed the accelerator pedal position (APP) sensor provides a change in the monitored signals. The engine control module (ECM) compares this against an electronic "map" and moves the electronic throttle valve via a pulse width modulation (PWM) control signal which is in proportion to the accelerator pedal position (APP) angle signal. The system is required to

1. Regulate the calculated intake air load based on the accelerator pedal sensor input signals and programmed mapping.
2. Monitor the drivers input request for cruise control operation.
3. Automatically position the electronic throttle for accurate cruise control.
4. Perform all dynamic stability control throttle control interventions.
5. Monitor and carry out maximum engine and road speed cut out.

A software strategy within the engine control module (ECM) enables the throttle position to be calibrated each ignition cycle. When the ignition is turned OFF, the engine control module (ECM) performs a self test and calibration routine on the electronic throttle by closing the throttle fully. The power is then removed and the engine control module (ECM) checks that the throttle returns to the reference position under the pressure from the spring.

Scheme 42

The accelerator pedal position (APP) sensor is located in a plastic housing which is integral with the throttle pedal. The housing is injection molded and provides location for the accelerator pedal position (APP) sensor. The sensor is mounted externally on the housing and is secured with two Torx screws. The external body of the sensor has a six pin connector which accepts a connector on the vehicle wiring harness.

The sensor has a spigot which protrudes into the housing and provides the pivot point for the pedal mechanism. The spigot has a slot which allows for a pin, which is attached to the sensor potentiometers, to rotate through approximately 90 degrees, which relates to pedal movement. The pedal is connected via a link to a drum, which engages with the sensor pin, changing the linear movement of the pedal into rotary movement of the drum. The drum has two steel cables attached to it. The cables are secured to two tension springs which are secured in the opposite end of the housing. The springs provide 'feel' on the pedal movement and require an effort from the driver similar to that of a cable controlled throttle. A detente mechanism is located at the forward end of the housing and is operated by a ball located on the drum. At near maximum throttle pedal movement, the ball contacts the detente mechanism. A spring in the mechanism is compressed and gives the driver the feeling of depressing a 'kickdown' switch when full pedal travel is achieved.

The accelerator pedal position (APP) sensor signals are checked for range and plausibility. Two separate reference voltages are supplied to the pedal. Should one sensor fail, the other is used as a 'limp-home' input. In limp home mode due to an accelerator pedal position (APP) signal failure the engine control module (ECM) will limit the maximum engine speed to 2000 rpm.

The accelerator pedal position (APP) sensor has two potentiometer tracks which each receive a 5V input voltage from the engine control module (ECM). Track 1 provides an output of 0.5V with the pedal at rest and 2.0V at 100% full throttle. Track 2 provides an output of 0.5V with the pedal at rest and 4.5V at 100% full throttle. The signals from the two tracks are used by the engine control module (ECM) to determine fueling for engine operation and also by the engine control module (ECM) and the transmission control module (TCM) to initiate a kickdown request for the automatic transmission.

The engine control module (ECM) monitors the outputs from each of the potentiometer tracks and can determine the position, rate of change and direction of movement of the throttle pedal. The 'closed throttle' position signal is used by the engine control module (ECM) to initiate idle speed control and also overrun fuel cut-off.

OXYGEN SENSORS

There are four oxygen sensors located in the exhaust system. Two upstream before the catalytic converter and two down stream after the catalytic converter. The sensor monitors the level of oxygen in the exhaust gases and is used to control the fuel/air mixture. Positioning a sensor in the stream of exhaust gasses from each bank enables the engine control module (ECM) to control the fueling on each bank independently of the other, allowing much closer control of the air/fuel ratio and catalyst conversion efficiency.

Scheme 43

Scheme 44

The oxygen sensors need to operate at high temperatures in order to function correctly. To achieve the high temperatures required, the sensors are fitted with heater elements that are controlled by a pulse width modulation (PWM) signal from the engine control module (ECM). The heater elements are operated immediately following engine start and also during low load conditions when the temperature of the exhaust gases is insufficient to maintain the required sensor temperatures. A non-functioning heater delays the sensor's readiness for closed loop control and influences emissions. The pulse width modulation (PWM) duty cycle is carefully controlled to prevent thermal shock to cold sensors.

UHEGO (Universal Heated Exhaust Gas Oxygen) sensors also known as Linear or "Wide Band" sensors produces a constant voltage, with a variable current that is proportional to the oxygen content. This allows closed loop fueling control to a target lambda, i.e. during engine warm up (after the sensor has reached operating temperature and is ready for operation). This improves emission control.

The HEGO sensor uses Zirconium technology that produces an output voltage dependant upon the ratio of exhaust gas oxygen to the ambient oxygen. The device contains a Galvanic cell surrounded by a gas permeable ceramic, the voltage of which depends upon the level of O2 defusing through. Nominal output voltage of the device for l =1 is 300 to 500m volts. As the fuel mixture becomes richer (l<1) the voltage tends towards 900m volts and as it becomes leaner (l>1) the voltage tends towards 0 volts. Maximum tip temperature is 1, 000 Degrees Celsius for a maximum of 100 hours.

Sensors age with mileage, increasing their response time to switch from rich to lean and lean to rich. This increase in response time influences the engine control module (ECM) closed loop control and leads to progressively increased emissions. Measuring the period of rich to lean and lean to rich switching monitors the response rate of the upstream sensors.

Diagnosis of electrical faults is continually monitored in both the upstream and downstream sensors. This is achieved by checking the signal against maximum and minimum threshold, for open and short circuit conditions.

Oxygen sensors must be treated with the utmost care before and during the fitting process. The sensors have ceramic material within them that can easily crack if dropped/banged or over-torqued. The sensors must be torqued to the required figure, (40-50Nm), with a calibrated torque wrench. Care should be taken not to contaminate the sensor tip when anti-seize compound is used on the thread. Heated sensor signal pins are tinned and universal are gold plated. Mixing up sensors could contaminate the connectors and affect system performance.

FAILURE MODES

1. Mechanical fitting & integrity of the sensor.
2. Sensor open circuit/disconnected.
3. Short circuit to vehicle supply or ground.
4. Lambda ratio outside operating band.
5. Crossed sensors bank A & B.
6. Contamination from leaded fuel or other sources.
7. Change in sensor characteristic.
8. Harness damage.
9. Air leak into exhaust system.

FAILURE SYMPTOMS

1. Default to Open Loop fueling for the particular cylinder bank
2. High CO reading.
3. Strong smell of H02S (rotten eggs) till default condition.
4. Excess Emissions.

It is possible to fit front and rear sensors in their opposite location. However the harness connections are of different gender and color to ensure that the sensors cannot be incorrectly connected. In addition to this the upstream sensors have two holes in the shroud, whereas the down stream sensors have four holes in the shroud for the gas to pass through.

GENERATOR

The Generator has a power control module voltage regulator for use in a 14V charging system with 6÷12 zener diode bridge rectifiers.

The engine control module (ECM) monitors the load on the electrical system via pulse width modulation (PWM) signal and adjusts the generator output to match the required load. The engine control module (ECM) also monitors the battery temperature to determine the generator regulator set point. This characteristic is necessary to protect the battery; at low temperatures battery charge acceptance is very poor so the voltage needs to be high to maximize any rechargeability, but at high temperatures the charge voltage must be restricted to prevent excessive gassing of the battery with consequent water loss.

The Generator has a smart charge capability that will reduce the electrical load on the Generator reducing torque requirements, this is implemented to utilize the engine torque for other purposes. This is achieved by monitoring three signals to the engine control module (ECM)

1. Generator sense (A sense), measures the battery voltage at the central junction box (CJB).
2. Generator communication (Alt Com) communicates desired Generator voltage set point from engine control module (ECM) to Generator.
3. Generator monitor (Alt Mon) communicates the extent of Generator current draw to engine control module (ECM). This signal also transmits faults to the engine control module (ECM) which will then sends a message to the instrument pack on the controller area network (CAN) bus to illuminate the charge warning lamp. Refer to «Generator»(ref-522663-S25745195272013020600000) .

FUEL INJECTORS

The engine has 8 fuel injectors (one per cylinder), each injector is directly driven by the engine control module (ECM). The injectors are fed by a common fuel rail as part of a 'returnless' fuel system. The fuel rail pressure is regulated to 4.5 bar by a fuel pressure regulator which is integral to the fuel pump module, within the fuel tank. The injectors can be checked by resistance checks. There is a fuel pressure test Schrader valve attached to the fuel rail on the front LH side for fuel pressure testing purposes. The engine control module (ECM) monitors the output power stages of the injector drivers for electrical faults.

The injectors have a resistance of 13.8 Ohms ± 0.7 Ohms @ 20 Degrees Celsius Refer to Fuel Charging And Controls .

IGNITION COILS

The V8 engine is fitted with eight plug-top coils that are driven directly by the engine control module (ECM). This means that the engine control module (ECM), at the point where sufficient charge has built up, switches the primary circuit of each coil and a spark is produced in the spark plug. The positive supply to the coil is fed from a common fuse. Each coil contains a power stage to trigger the primary current. The engine control module (ECM) sends a signal to each of the coils power stage to trigger the power stage switching. Each bank has a feedback signal that is connected to each power stage. If the coil power stage has a failure the feedback signal is not sent, causing the engine control module (ECM) to store a fault code appropriate to the failure.

The engine control module (ECM) calculates the dwell time depending on battery voltage and engine speed to ensure constant secondary energy. This ensures sufficient secondary (spark) energy is always available, without excessive primary current flow thus avoiding overheating or damage to the coils.

The individual cylinder spark timing is calculated from a variety of inputs

1. Engine speed and load.
2. Engine temperature.
3. Knock control.
4. Auto gearbox shift control.
5. Idle speed control.

FUEL PUMP RELAY

The V8 engine has a returnless fuel system. The system pressure is maintained at a constant 4 bar (59 Psi), with no reference to intake manifold pressure. The fuel is supplied to the injectors from a fuel pump fitted within the fuel tank. The electrical supply to this fuel pump is controlled by the engine control module (ECM) via a relay and the restraints control module (RCM) which will turn the fuel off upon a vehicle impact. The fuel system is pressurized as soon as the engine control module (ECM) is powered up, the pump is then switched off until engine start has been achieved.

VISCOUS FAN CONTROL

The engine control module (ECM) controls a viscous coupled fan to provide engine cooling. The engine control module (ECM) supplies the fan with a pulse width modulation (PWM) signal that controls the amount of slippage of the fan, thus providing the correct amount of cooling fan speed and airflow. The EMS uses a Hall Effect sensor to determine the fan speed.

E-BOX FAN

The engine control module (ECM) controls an electric fan to provide cooling in the E-Box. The engine control module (ECM) uses a hardwired signal to switch the fan on or off based on its internal temperature sensor.

VARIABLE VALVE TIMING (VVT)

Variable valve timing is used on the V8 engine to enhance low and high speed engine performance and idle speed quality.

For each intake camshaft the VVT system comprises

1. VVT unit
2. Valve timing solenoid

The VVT system alters the phase of the intake valves relative to the fixed timing of the exhaust valves, to alter

1. The mass of air flow to the cylinders.
2. The engine torque response.
3. Emissions.

The VVT unit uses a vane type device to control the camshaft angle. The system operates over a range of 48 degrees and is advanced or retarded to its optimum position within this range.

The VVT system is controlled by the engine control module (ECM) based on engine load and speed along with engine oil temperature to calculate the appropriate camshaft position.

The VVT system provides the following advantages

1. Reduced engine emissions and improved fuel consumption which in turn improves the engines internal exhaust gas recirculation (EGR) effect over a wider operating range.
2. Enhanced full load torque characteristics.
3. Improved fuel economy through optimized torque over the engine speed range.

The VVT unit is a hydraulic actuator mounted on the end of the intake camshaft. The unit advances or retards the camshaft timing to alter the camshaft to crankshaft phase. The engine control module (ECM) controls the VVT timing unit via a oil control solenoid. The oil control solenoid routes oil pressure to the advance or retard chambers either side of the vanes within the VVT unit.

The VVT unit is driven by the primary drive chain and rotates relative to the exhaust camshaft. When the engine control module (ECM) requests a retard in camshaft timing the oil control solenoid is energized which moves the shuttle valve in the solenoid to the relevant position allowing oil pressure to flow out of the advance chambers in the VVT unit whilst simultaneously allowing oil pressure into the retard chambers.

The engine control module (ECM) controls the advancing and retarding of the VVT unit based on engine load and speed. The engine control module (ECM) sends an energize signal to the oil control solenoid until the desired VVT position is achieved. When the desired VVT position is reached, the energizing signal is reduced to hold the oil control solenoid position and consequently desired VVT position. This function is under closed loop control and the engine control module (ECM) can sense any variance in shuttle valve oil pressure via the camshaft position sensor and can adjust the energizing signal to maintain the shuttle valve hold position.

VVT operation can be affected by engine oil temperature and properties. At very low oil temperatures the movement of the VVT mechanism will be slow due to the high viscosity of the oil. While at high oil temperatures the low oil viscosity may impair the VVT operation at low oil pressures. The oil pump has the capacity to cope with these variations in oil pressure while an oil temperature sensor is monitored by the engine control module (ECM) to provide oil temperature feedback. At extremely high oil temperatures the engine control module (ECM) may limit the amount of VVT advance in order to prevent the engine from stalling when returning to idle speed.

VVT does not operate when engine oil pressure is below 1.25 bar. This is because there is insufficient pressure to release the VVT units internal stopper pin. This occurs when the engine is shut down and the VVT unit has returned to the retarded position. The stopper pin locks the VVT unit to the camshaft to ensure camshaft stability during the next start up. Refer to Engine .

Valve Timing Solenoid

The valve timing solenoid controls the position of the shuttle valve in the bush carrier. A plunger on the solenoid extends when the solenoid is energized and retracts when the solenoid is de-energized.

When the valve timing solenoids are de-energized, the coil springs in the bush carriers position the shuttle valves to connect the valve timing units to drain. In the valve timing units, the return springs hold the ring pistons and gears in the retarded position. When the valve timing solenoids are energized by the engine control module (ECM), the solenoid plungers position the shuttle valves to direct engine oil to the valve timing units. In the valve timing units, the oil pressure overcomes the force of the return springs and moves the gears and ring pistons to the advanced position. System response times are 1.0 second maximum for advancing and 0.7 second maximum for retarding. While the valve timing is in the retarded mode, the engine control module (ECM) produces a periodic lubrication pulse. This momentarily energizes the valve timing solenoids to allow a spurt of oil into the valve timing units. The lubrication pulse occurs once every 5 minutes.

EXHAUST GAS RECIRCULATION (EGR) VALVE

The exhaust gas recirculation (EGR) valve is an electrically controlled valve that allows burned exhaust gas to be recirculated back into the engine. The exhaust gas recirculation (EGR) valve consists of a stepper motor that opens and closes the valve in steps. Since exhaust gas has much less oxygen than air, it is basically inert. It takes the place of air in the cylinder and reduces combustion temperature. As the combustion temperature is reduced, so are the oxides of nitrogen (NOx).

The EGR valve is located on the intake manifold with a pipe connecting the exhaust manifold to the valve. Connection between the sensor and the harness is via a six-way connector. Refer to Description & Operation .

ENGINE CONTROL MODULE (ECM) ADAPTIONS

The engine control module (ECM) has the ability to adapt the values it uses to control certain outputs. This capability ensures the EMS can meet emissions legislation and improve the refinement of the engine throughout its operating range.

The components which have adaptions associated with them are

1. The accelerator pedal position (APP) sensor
2. The HO2S
3. The mass air flow (MAF)/intake air temperature (IAT) sensor
4. The crankshaft position (CKP) sensor
5. Electric throttle body.

UHEGO/HEGO AND MAF/IAT SENSOR

There are several adaptive maps associated with the fueling strategy. Within the fueling strategy the engine control module (ECM) calculates short-term adaptions and long term adaptions. The engine control module (ECM) will monitor the deterioration of the oxygen sensors (HEGO and UHEGO) over a period of time. It will also monitor the current correction associated with the sensors.

The engine control module (ECM) will store a fault code in circumstances where an adaption is forced to exceed its operating parameters. At the same time, the engine control module (ECM) will record the engine speed, engine load and intake air temperature.

CRANKSHAFT POSITION (CKP) SENSOR

The characteristics of the signal supplied by the crankshaft position (CKP) sensor are learned by the engine control module (ECM). This enables the engine control module (ECM) to set an adaption and support the engine misfire detection function. Due to the small variation between different flywheels and different crankshaft position (CKP) sensors, the adaption must be reset if either component is renewed, or removed and refitted. It is also necessary to reset the flywheel adaption if the engine control module (ECM) is renewed or replaced. The engine control module (ECM) supports four flywheel adaptions for the crankshaft position (CKP) sensor. Each adaption relates to a specific engine speed range. The engine speed ranges are detailed in the table below

MISFIRE DETECTION

Legislation requires that the engine control module (ECM) must be able to detect the presence of an engine misfire. It must be able to detect misfires at two separate levels. The first level is a misfire that could lead to the vehicle emissions exceeding 1.5 times the Federal Test Procedure (FTP) requirements for the engine. The second level is a misfire that may cause catalyst damage.

The engine control module (ECM) monitors the number of misfire occurrences within two engine speed ranges. If the engine control module (ECM) detects more than a predetermined number of misfire occurrences within either of these two ranges, over two consecutive journeys, the engine control module (ECM) will record a fault code and details of the engine speed, engine load and engine coolant temperature. In addition, the engine control module (ECM) monitors the number of misfire occurrences that happen in a 'window' of 200 engine revolutions. The misfire occurrences are assigned a weighting according to their likely impact on the catalysts. If the number of misfires exceeds a certain value, the engine control module (ECM) stores catalyst-damaging fault codes, along with the engine speed, engine load and engine coolant temperature.

The signal from the crankshaft position sensor indicates how fast the poles on the flywheel are passing the sensor tip. A sine wave is generated each time a pole passes the sensor tip. The engine control module (ECM) can detect variations in flywheel speed by monitoring the sine wave signal supplied by the crankshaft position sensor.

By assessing this signal, the engine control module (ECM) can detect the presence of an engine misfire. At this time, the engine control module (ECM) will assess the amount of variation in the signal received from the crankshaft position sensor and assigns a roughness value to it. This roughness value can be viewed within the real time monitoring feature, using T4. The engine control module (ECM) will evaluate the signal against a number of factors and will decide whether to count the occurrence or ignore it. The engine control module (ECM) can assign a roughness and misfire signal for each cylinder, (i.e. identify which cylinder is misfiring).

GENERIC ELECTRONIC MODULE (GEM)

The engine control module (ECM) is connected to ignition switch I and II. When the ignition is turned on 12V is applied to the Ignition Sense input. The engine control module (ECM) then starts its power up routines and turns on the engine control module (ECM) main relay; the main power to the engine control module (ECM) and it's associated system components. When the ignition is turned OFF the engine control module (ECM) will maintain its powered up state for up to 20 minutes while it initiates its power down routine and on completion will turn off the engine control module (ECM) main relay. The engine control module (ECM) will normally power down in approximately 60 seconds, do not disconcert the battery until the engine control module (ECM) is completely powered down.

Scheme 45

Scheme 46

Note. A= Hardwired D= controller area network (CAN)

HEATED OXYGEN SENSOR (HO2S) LH

SPECIAL TOOLS Tool Illustration Tool Name Tool Number Wrench, HO2S 310-121 (LRT-19-014)

Scheme 47

Scheme 48

Scheme 49

Scheme 50

1. Raise and support the vehicle.
2. Disconnect the LH catalytic converter from the exhaust manifold. Remove and discard the 2 bolts.
3. Disconnect the RH catalytic converter from the exhaust manifold. Remove and discard the 2 bolts.
4. Using the special tool, remove the HO2S. Release the wiring harness. Disconnect the electrical connector.

Scheme 51

1. Using the special tool, install the HO2S. Clean the components. Apply an anti-seize compound to the thread of the HO2S. Tighten the HO2S to 45 Nm (33 lb.ft). Connect the electrical connector. Attach the wiring harness.
2. Position the RH catalytic converter to the exhaust manifold. Clean the components. Tighten the new bolts to 22 Nm (16 lb.ft).
3. Position the LH catalytic converter to the exhaust manifold. Clean the components. Tighten the new bolts to 22 Nm (16 lb.ft).
4. Using the approved diagnostic equipment, clear the powertrain control module (PCM) adaptions.

Scheme 52

1. Disconnect the battery ground cable. Refer to «Specifications»(ref-522601-S06524472732013011500000) .
2. Disconnect the mass air flow (MAF) sensor electrical connector.
3. Remove the MAF sensor. Remove the 2 screws.

CATALYST MONITOR SENSOR LH

SPECIAL TOOLS Tool Illustration Tool Name Tool Number Wrench, HO2S 310-121 (LRT-19-014)

Scheme 53

Scheme 54

1. Raise and support the vehicle.
2. Disconnect the LH catalytic converter from the exhaust manifold. Remove and discard the 2 bolts.
3. Disconnect the RH catalytic converter from the exhaust manifold. Remove and discard the 2 bolts.
4. Remove the catalyst monitor sensor electrical connector heat shield. Remove the 2 bolts.
5. Using the special tool, remove the catalyst monitor sensor. Release the wiring harness. Disconnect the electrical connector.