Land Rover Lesson 2 Auto Trans Coolingine Rover Manual

							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 inlet 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:
•Variable inlet cam timing
•Cylinder recognition
•Enabling sequential fuel injection
•Knock control
•Cylinder identification for diagnostic purposes.
Failure symptoms include:
•Ignition timing reverting to the base mapping, with
no cylinder correction.
•Active knock control is disabled, along with its
diagnostic (Safe ignition map - loss of performance).
•Quick cam / crank synchronisation on start disabled.
•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 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 -30
Degrees Celsius to 125 Degrees Celsius. When a
defective coolant sensor is detected, the ECM uses the
oil temperature sensor value.
ENGINE OIL TEMPERATURE
SENSOR
Oil temperature is monitored through a temperature
sensor mounted in the oil system. This component is a
NTC (negative temperature coefficient). The sensor is
mounted next to the oil pressure sensor at the front of
the engine and locates into the oil filter bracket.
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							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 inlet 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 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
stichometric 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:
•During driving the engine RPM might dip, before
recovering.
•Difficulty in starting or start - stall.
•Poor throttle response / engine performance.
•Lambda control and idle speed control halted.
•Emissions incorrect.
•AFM signal offset
The Inlet Air Temperature (IAT) sensor is integrated
into the Mass Air Flow meter. 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
ECM. The voltage from this sensor changes as the
sensor resistance changes, thus relating the air
temperature to the voltage measured by the ECM.
The ECM stores a 25°C default value for air temperature
in the event of a sensor failure.
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							MANIFOLD ABSOLUTE PRESSURE
SENSOR (MAP)
The 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 ECM. The sensor
is located on the rear of the air intake manifold.
DescriptionPin No
MAP signal1
Sensor supply2
Not used3
Sensor ground4
The output signal from the MAP sensor, together with
the CKP and IAT sensors, is used by the ECM to
calculate the amount of air induced into the cylinders.
This enables the ECM to determine ignition timing and
fuel injection duration values.
The MAP sensor receives a 5V supply voltage from pin
48 of ECM connector C0634 and provides an analogue
signal to pin 69 of ECM connector C0634, which relates
to the absolute manifold pressure and allows the ECM
to calculate engine load. The ECM provides a ground
for the sensor via pin 11 of ECM connector C0634.
If the MAP signal is missing, the ECM will substitute
a default manifold pressure reading based on crankshaft
speed and throttle angle. The engine will continue to
run with reduced drivability and increased emissions,
although this may not be immediately apparent to the
driver. The 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 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 ECM, which compares
them with `mapped signals stored in memory. From
this, the ECM can determine when detonation occurs
on individual cylinders. When detonation is detected,
the ECM retards the ignition timing on that cylinder for
a number of engine cycles, then gradually returns it to
the original setting.
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							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 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 ECM. The 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 ECM learns and
then modifies its internal mapping to compensate for
the variation in fuel quality. This feature is called
adaption. The ECM has the capability of adapting its
fuel and ignition control outputs in response to several
sensor inputs.
The ECM will cancel closed loop control of the ignition
system if the signal received from either knock sensor
becomes implausible. In these circumstances the 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 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:
•Electronic throttle control valve
•Accelerator pedal position sensor (APP)
•ECM
When the accelerator pedal is depressed the APP sensor
provides a change in the monitored signals. The ECM
compares this against an electronic “map” and moves
the electronic throttle valve via a pulse width modulated
(PWM) control signal which is in proportion to the APP
angle signal. The system is required to:
•Regulate the calculated intake air load based on the
accelerator pedal sensor input signals and
programmed mapping.
•Monitor the drivers input request for cruise control
operation.
•Automatically position the electronic throttle for
accurate cruise control.
•Perform all dynamic stability control throttle control
interventions.
•Monitor and carry out maximum engine and road
speed cut out.
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							A software strategy within the ECM enables the throttle
position to be calibrated each ignition cycle. When the
ignition is turned ON, the ECM performs a self test and
calibration routine on the electronic throttle by opening
and closing the throttle fully.
Electronic Throttle Pin Out Table
DescriptionPin No
Motor -1
Motor +2
Sensor ground3
Sensor 2 signal4
Sensor 1 signal5
5 volt supply6
ACCELERATOR PEDAL POSITION
SENSOR (APP)
The APP sensors are located on the accelerator pedal
assembly.
The APP sensors are used to determine the drivers
request for vehicle speed, acceleration and deceleration.
This value is used by the ECM and the throttle is opened
to the correct angle by an electric motor integrated into
the throttle body.
The 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 APP signal failure the ECM will limit the
maximum engine speed to 2000 rpm.
Accelerator Pedal Position Sensor (APP) Pin Out
Table
DescriptionPin No
APP2 ground1
APP 1 demand2
APP 1 ground3
Not used4
APP 2 demand5
Supply 2, 5 volt6
Supply 1, 5 volt7
Not used8
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 ECM to control the fuelling on each bank
independently of the other, allowing much closer control
of the air / fuel ratio and catalyst conversion efficiency.
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							Upstream Oxygen Sensors
Downstream Oxygen Sensors
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 PWM signal from the
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 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 fuelling 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 (l1) 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 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
•Mechanical fitting & integrity of the sensor.
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							•Sensor open circuit / disconnected.
•Short circuit to vehicle supply or ground.
•Lambda ratio outside operating band.
•Crossed sensors bank A & B.
•Contamination from leaded fuel or other sources.
•Change in sensor characteristic.
•Harness damage.
•Air leak into exhaust system.
Failure Symptoms
•Default to Open Loop fuelling for the particular
cylinder bank
•High CO reading.
•Strong smell of H02S (rotten eggs) till default
condition.
•Excess Emissions.
It is possible to fit front and rear sensors in their opposite
location. However the harness connections are of
different gender and colour 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 multifunction voltage regulator for
use in a 14V charging system with 6÷12 zener diode
bridge rectifiers.
The ECM monitors the load on the electrical system via
PWM signal and adjusts the generator output to match
the required load. The 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 maximise
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 utilise the
engine torque for other purposes. This is achieved by
monitoring three signals to the ECM:
•Generator sense (A sense), measures the battery
voltage at the Central Junction Box(CJB).
•Generator communication (Alt Com) communicates
desired Generator voltage set point from ECM to
Generator.
•Generator monitor (Alt Mon) communicates the
extent of Generator current draw to ECM. This signal
also transmits faults to the ECM which will then
sends a message to the instrument pack on the CAN
bus to illuminate the charge warning lamp.
FUEL INJECTORS
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							The engine has 8 fuel injectors (one per cylinder), each
injector is directly driven by the 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
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
IGNITION COILS
The V8 engine is fitted with eight plug-top coils that
are driven directly by the ECM. This means that the
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 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 ECM to store a fault code appropriate to the
failure.
The 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:
•Engine speed and load.
•Engine temperature.
•Knock control.
•Auto gearbox shift control.
•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 ECM via a relay and an Inertia Switch
which will turn the fuel off upon a vehicle impact. The
fuel system is pressurised as soon as the ECM is
powered up, the pump is then switched off until engine
start has been achieved.
VISCOUS FAN CONTROL
The ECM controls a viscous coupled fan to provide
engine cooling. The ECM supplies the fan with a 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.
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							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 inlet camshaft the VVT system comprises:
•VVT unit
•Valve timing solenoid
The VVT system alters the phase of the intake valves
relative to the fixed timing of the exhaust valves, to
alter:
•The mass of air flow to the cylinders.
•The engine torque response.
•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 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:
•Reduced engine emissions and improved fuel
consumption which in turn improves the engines
internal EGR effect over a wider operating range.
•Enhanced full load torque characteristics.
•Improved fuel economy through optimised torque
over the engine speed range.
Variable Valve Timing Unit
The VVT unit is a hydraulic actuator mounted on the
end of the inlet camshaft. The unit advances or retards
the camshaft timing to alter the camshaft to crankshaft
phase. The 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 ECM
requests a retard in camshaft timing the oil control
solenoid is energised 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 ECM controls the advancing and retarding of the
VVT unit based on engine load and speed. The ECM
sends an energise signal to the oil control solenoid until
the desired VVT position is achieved. When the desired
VVT position is reached, the energising signal is reduced
to hold the oil control solenoid position and
consequently desired VVT position. This function is
under closed loop control and the ECM can sense any
variance in shuttle valve oil pressure via the camshaft
position sensor and can adjust the energising 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
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							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
ECM to provide oil temperature feedback. At extremely
high oil temperatures the 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.
Valve Timing Solenoid
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 energised and
retracts when the solenoid is de-energised.
When the valve timing solenoids are de-energised, 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 energised by the 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 ECM produces a periodic lubrication pulse.
This momentarily energises 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 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.
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