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Home >> Land Rover >> 2010 >> LR2 (LF) L6-3.2L >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Description and Operation >> Electronic Engine Controls >> Part 1

Part 1






Electronic Engine Controls

COMPONENT LOCATION SHEET 1 OF 2









COMPONENT LOCATION SHEET 2 OF 2









OVERVIEW
The Engine Control Module (ECM) controls the following:
- Engine fueling
- Ignition timing
- Closed loop fueling
- Knock control
- Idle speed control
- Emission control
- On Board Diagnostics
- Speed control.
The ECM controls engine fueling by providing sequential fuel injection to all cylinders. Ignition is controlled by a direct ignition system, provided by 6 plug top coils. The 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 ECM uses a torque-based strategy to generate the torque required by the driver and other vehicle control modules. The ECM uses various sensors to determine the torque required from the engine. The ECM also interfaces with other vehicle electronic control modules via the high speed Controller Area Network (CAN) bus, to obtain additional information (for example road speed from the Anti-lock Brake System (ABS) module). The ECM 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.
The ECM also uses an electronic throttle system which comprises the electric throttle assembly and an Accelerator Pedal Position (APP) sensor.
The ECM also interfaces with the immobilization system to help prevent the vehicle being started without proper authorization. For additional information, refer to Anti-Theft - Active Anti-Theft - Active

CONTROL DIAGRAM SHEET 1 OF 2

NOTE:
A = Hardwired; N = Medium speed CAN bus; O = Local Interconnect Network (LIN) bus









CONTROL DIAGRAM SHEET 2 OF 2

NOTE:
A = Hardwired; D = High speed CAN bus; N = Medium speed CAN bus









ENGINE CONTROL MODULE (ECM)





The ECM is located on a bracket in a central position on the engine compartment firewall. The ECM is attached to a housing and secured with 4 screws. The housing is located in the bracket and locked in position.
The ECM is supplied with battery voltage from fuses located in the BJB. A permanent battery supply is provided to ensure adaptive data is not lost when the engine is switched off.
A regulator, located within the ECM, supplies a 5V current to internal components such as the micro-processor unit. Other components or functions requiring full battery voltage are controlled by external relays or internal power stages.
The micro-processor within the ECM receives signals from different components and control modules and uses a program within the ECM software to interpret the signal information and issue signals which relate to how the engine components and functions should be controlled.
The ECM receives inputs from the following:
- CMP sensors
- CKP sensor
- Fuel rail pressure sensor
- MAF sensor
- Knock sensors
- Fuel rail temperature/pressure sensor
- ECT sensor
- Engine oil level/temperature sensor
- Manifold Absolute Pressure (MAP) sensor
- Electric throttle - Throttle Position (TP) sensor
- APP sensor
- Fuel tank leakage monitoring module (NAS only)
- Cooling fan control
- Heated Oxygen sensors (HO2S)
- Stop lamp switch (via Central Junction Box (CJB))
- Speed control inhibit switch
- Intake Air Temperature (IAT) sensor
- Ambient Air Temperature (AAT) sensor
- Transmission Control Module (TCM).
The ECM sends outputs to the following:
- Main relay
- Air Conditioning (A/C) relay
- Fuel injectors
- Ignition coils
- Engine cooling fan control
- Electric throttle
- Electric fuel pump driver module
- Variable Camshaft Timing (VCT) solenoids
- Starter relay control
- Variable intake manifold control valves
- Variable inlet cam profile switching solenoid valves
- Transmission Control Module (TCM).

SENSORS
The ECM optimizes engine performance by interpreting signals from numerous vehicle sensors and other inputs. Some of these signals are produced by the actions of the driver, some are supplied by sensors located on and around the engine and some are supplied by other vehicle systems.

Camshaft Position (CMP) Sensor





Two CMP sensors are located in the camshaft housing at the Left Hand (LH) end of the engine. The sensors are located in a hole in the housing and are secured with a screw. There is a CMP sensor for each camshaft.
The CMP sensors monitor the position of the camshafts to establish ignition timing order, fuel injection triggering and for accurate Variable Camshaft Timing (VCT) operation. The ECM can also use the CMP sensors to determine which cylinder has a misfire or knock using the CMP signal output.
The CMP sensor is a Hall-effect sensor which switches a 5V supply from the ECM on and off. The supply is switched when teeth machined onto a pulse wheel on the camshaft pass by the tip of the sensor. The teeth are of differing shapes, so the ECM can determine the exact position of the camshaft at any time. When one of the teeth passes by the sensor tip, a signal is transmitted to the ECM which can vary between 0 and 5V. The signal is high when a tooth is directly adjacent to the sensor and is low when the tooth is away from the sensor.
Failure of one or both of the sensors will result in the ECM using a default map for ignition timing and knock control will be disabled.
The ECM monitors the sensor for correct function and can diagnose and store fault codes for sensor faults. These can be retrieved using a Land Rover approved diagnostic system.

Crankshaft Position (CKP) Sensor





The CKP sensor is located on the forward side of the transmission torque converter housing, in line with the engine flywheel. The sensor is secured with a bolt into a bracket attached to the gear housing. A reluctor ring is fitted to the outer diameter of the crankshaft flexplate and the sensor reacts to the gaps in the reluctor ring to determine engine speed and position information. The sensor has 2 wires from the ECM sensor ground and a feedback signal.
The CKP sensor is an inductive type sensor which produces a sinusoidal output voltage signal. This voltage is induced by the proximity of the moving reluctor ring gaps, which excite the magnetic flux around the tip of the sensor when each gap passes. This output voltage will increase in magnitude and frequency as the engine speed rises determined by an increase in the speed at which the gaps on the reluctor ring pass the sensor. The signal voltage can be as low as 0.1V at low engine speeds and up to 100V at high engine speeds. The ECM does not react to the output voltage (unless the voltage is extremely low or high), instead it measures the time intervals between each pulse (signal frequency). The signal is determined by the number of gaps passing the sensor, and the speed at which they pass. The reluctor ring has 2 gaps missing to give the ECM a synchronization point and determine the position of the crankshaft. The CKP sensor signal is also used for misfire
detection.
The signal produced by the CKP sensor is critical to engine running. Failure of the sensor when the engine is running will result in the engine stopping immediately. The engine can be restarted using signals from the CMP sensors but the engine speed will be limited to 3000 rpm and the Malfunction Indicator Lamp (MIL) will be illuminated.
The ECM monitors the sensor for correct function and can diagnose and store fault codes for sensor faults. These can be retrieved using a Land Rover approved diagnostic system.

Fuel Rail Pressure/Temperature Sensor





The fuel rail pressure/temperature sensor is located on the LH end of the fuel rail. The ECM supplies the combined pressure and temperature sensor with a 5V reference voltage and a ground and measures the returned signals for pressure and temperature.

Fuel pressure
The fuel pressure sensor is a peizo resistor type sensor. The sensor receives a 5V reference voltage from the ECM and produces an analogue signal of between 0 and 5V depending on the pressure sensed. Low pressure gives a low voltage output and consequently high pressure gives a higher voltage output. The ECM uses this pressure signal to adjust the fuel pump module output pressure by sending controlling signals to the FPDM and for injector timing.
The ECM monitors the fuel pressure sensor for faults and can store fault related codes. These can be retrieved using a Land Rover approved diagnostic system. Sensor operation can also be checked using a Land Rover approved diagnostic system to check fuel pressure. If no fuel pressure is in the fuel rail, the sensor will read and output atmospheric pressure.

Fuel Temperature
The fuel temperature sensor is a Negative Temperature Co-efficient (NTC) sensor. The sensing thermistor element resistance decreases as the sensor temperature increases. The ECM supplies the sensor with a 5V reference voltage and a ground and measures the returned signal as a temperature.
The resistance in the sensor changes with fuel temperature. A low fuel temperature will result in a high voltage being returned to the ECM and high fuel temperature will return a low voltage reading of between 0 - 5V.
The ECM monitors the fuel temperature sensor for faults and can store fault related codes. These can be retrieved using a Land Rover approved diagnostic system. The ECM uses the ECT temperature signal as a default but only up to a maximum of 100°C (212°F).

Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor





The MAF/IAT sensor is located in the outlet pipe from the air cleaner housing. The combined MAF/IAT functions are connected to the ECM on separate wires. The sensor has an extended moulding which is located in a central position in the air flow through the air cleaner housing outlet pipe, through which the air flow and temperature are measured.

Mass Air Flow (MAF) Sensor
The MAF sensor measures the mass of air being drawn into the engine. The air mass is calculated by the cooling effect of inlet air passing over a 'hot film' element contained within the sensor. The higher the air flow, the greater the cooling effect on the element which in turn lowers the electrical resistance of the 'hot film' element. The ECM uses this resistance value to calculate the air mass or volume of air flowing into the engine.
The MAF sensor receives a battery voltage supply via the ECM and the main relay. The ECM provides a ground and a signal path for the resistance signal from the 'hot film' sensor. The analogue signal from the MAF sensor varies between 0.5 and 5V. Low air flow gives a low voltage and high air flow gives a high voltage.
The MAF signal is used by the ECM to determine:
- the correct fuel quantity (injection period) to maintain the correct air/fuel ratio required for correct operation of the engine and the catalysts
- the ignition timing
- the engine load.
The ECM monitors the MAF sensor for faults and can store fault related codes. These can be retrieved using a Land Rover approved diagnostic system.

Intake Air Temperature (IAT) Sensor
The IAT sensor measures the temperature of the intake air entering the engine. The sensor is a temperature dependant resistor (thermistor). The thermistor is a NTC sensor element. The element resistance decreases as the sensor temperature increases. The ECM supplies the sensor with a 5V reference voltage and a ground and measures the returned signal as a temperature.
The resistance in the sensor changes with intake air temperature. A low intake air temperature will result in a high voltage being returned to the ECM and high intake air temperature will return a low voltage reading of between 0 - 5V.
The ECM monitors the IAT sensor for faults and can store fault related codes. These can be retrieved using a Land Rover approved diagnostic system. If the IAT sensor fails, the ECM uses a default temperature value using the fuel rail pressure/temperature sensor.

Knock Sensors





Two knock sensors are located on the front of the engine and are each secured to threaded holes in the engine cylinder block with a bolt. The knock sensors are used by the ECM to monitor combustion knocking or vibration generated by ignition combustion. The knock sensors are each connected to the ECM via a twisted pair of wires which reduces electrical interference disrupting the signal produced.
Each knock sensor contains a peizo-ceramic crystal which produces a voltage when an external force applies pressure or load on it. When the engine is running, compression waves produced by the combustion process, creates pressure waves which pass through the engine cylinder block. These pressure waves are detected by the knock sensors and the deflection of the crystal caused by the pressure waves causes the sensors to produce an output signal. The signals are passed to the ECM which compares them with stored mapped signals in its memory.
The ECM can then determine when the correct combustion occurs in individual cylinders. If incorrect combustion detonation is detected, the ECM can retard the ignition timing on that cylinder for a number of combustion cycles. The ignition timing will be gradually returned to its optimal settings. If the knock is still detected the ECM will increase the injection period, which has a cooling effect on that cylinder.
The signals from the knock sensors are used in conjunction with the CMP sensors and the CKP sensor to determine the ignition cycle and therefore identify which cylinder is knocking. The ECM is programmed to use ignition maps based on high quality 95-98 RON fuel. If fuel of a poor quality such as 91 RON is used the engine may suffer from knock (pinking) for a period of time. The ECM is capable of learning and adapting to the low grade fuel and will modify its internal ignition mapping to compensate for the low grade fuel. This feature of the ECM is called adaption.
If one or both knock sensors fail or the signal becomes implausible, the ECM will cancel closed loop control of the ignition system. The ECM will use a default 'safe' ignition map to ensure the pre-detonation does not damage the engine by setting maximum retard control on spark advance. The driver may notice 'pinking' under certain driving conditions and a loss of performance. The ECM monitors the knock sensors for faults and can store fault related codes. These can be retrieved using a Land Rover approved diagnostic system.

Engine Coolant Temperature (ECT) Sensor





The ECT sensor is located in the thermostat housing, on the front of the engine, below the inlet manifold. The ECT sensor is a thermistor type sensor used by the ECM to monitor the engine coolant temperature. The ECM uses the temperature information for the following functions:
- regulate the injection period
- set engine idle target speed
- control the engine cooling fan(s)
- determine operation of the A/C compressor
- determine operation of the purge valve and catalytic converter heating function.
The sensor is a Negative Temperature Co-efficient (NTC) thermistor element. The element resistance decreases as the sensor temperature increases. The ECM supplies the sensor with a 5V reference voltage and a ground and measures the returned signal as a temperature.
The ECT sensor is important to the correct running of the engine as a richer mixture is required at low engine coolant temperatures for efficient starting and smooth cold running. As the engine coolant temperature increases, the ECM uses the temperature signal from the sensor to lean off the fuel mixture to maintain optimum emissions and performance.
The ECM monitors the ECT sensor for faults and can store fault related codes. These can be retrieved using a Land Rover approved diagnostic system. If the ECT sensor fails, the ECM uses a default value of 90°C (194°F). The electric fan control module is sent a default coolant temperature value of 105°C (221°F) and switches the cooling fan on permanently.
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