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2) ECU Control
(1) Function
a. ECU Function
ECU receives and analyzes signals from various sensors and then modifies those signals into
permissible voltage levels and analyzes to control respective actuators.
ECU microprocessor calculates injection period and injection timing proper for engine piston speed
and crankshaft angle based on input data and stored specific map to control the engine power and
emission gas.
Output signal of the ECU microprocessor drives pressure control valve to control the rail pressure and
activates injector solenoid valve to control the fuel injection period and injection timing; so controls
various actuators in response to engine changes. Auxiliary function of ECU has adopted to reduce
emission gas, improve fuel economy and enhance safety, comforts and conveniences. For example,
there are EGR, booster pressure control, autocruise (export only) and immobilizer and adopted CAN
communication to exchange data among electrical systems (automatic T/M and brake system) in the
vehicle fluently. And Scanner can be used to diagnose vehicle status and defectives.
Operating temperature range of ECU is normally -40 to +85°C and protected from factors like
oil, water and electromagnetism and there should be no mechanical shocks.
To control the fuel volume precisely under repeated injections, high current should be applied instantly
so there is injector drive circuit in the ECU to generate necessary current during injector drive stages.
Current control circuit divides current applying time (injection time) into full-in-current-phase and hold-
current-phase and then the injectors should work very correctly under every working condition.
b. Control Function
Controls by operating stages
To make optimum combustion under every operating stage, ECU should calculate proper injection
volume in each stage by considering various factors.
Starting injection volume control
During initial starting, injecting fuel volume will be calculated by function of temperature and engine
cranking speed. Starting injection continues from when the ignition switch is turned to ignition
position to till the engine reaches to allowable minimum speed.
Driving mode control
If the vehicle runs normally, fuel injection volume will be calculated by accelerator pedal travel and
engine rpm and the drive map will be used to match the drivers inputs with optimum engine power. -
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C. Idle Speed Controller
The idle speed controller consists of 2 principal modules:
The first module determines the required idle speed according to:
* The operating conditions of the engine (coolant temperature, gear engaged)
* Any activation of the electrical consumers (power steering, air conditioning, others)
* The battery voltage
* The presence of any faults liable to interface with the rail pressure control or the injection control.
In this case, increase the idle speed to prevent the engine from stalling.
The second module is responsible for providing closed loop control of the engine's idle speed by
adapting the minimum fuel according to the difference between the required idle speed and the
engine speed. -
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D. Flow Limitation
The flow limitation strategy is based on the following strategies:
The flow limitation depending on the filling of the engine with air is determined according to the
engine speed and the air flow. This limitation allows smoke emissions to be reduced during
stabilized running.
The flow limitation depending on the atmospheric pressure is determined according to the
engine speed and the atmospheric pressure. It allows smoke emissions to be reduced when
driving at altitude.
The full load flow curve is determined according to the gear engaged and the engine speed. It
allows the maximum torque delivered by the engine to be limited.
A performance limitation is introduced if faults liable to upset the rail pressure control or the
injection control are detected by the system. In this case, and depending on the gravity of the
fault, the system activates: -
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Reduced fuel logic 1: Guarantees 75 % of the performance without limiting the engine speed.
Reduced fuel logic 2: Guarantees 50 % of the performance with the engine speed limited to
3,000 rpm.
Reduce fuel logic 3: Limits the engine speed to 2,000 rpm.
The system chooses the lowest of all values.
A correction depending on the coolant temperature is added to the flow limitation. This correction
makes it possible to reduce the mechanical stresses while the engine is warming up.
The correction is determined according to the coolant temperature, the engine speed and the time
which has passed since starting.
E. Superchager Flow Demand
The supercharge flow is calculated according to the engine speed and the coolant temperature. A
correction depending on the air temperature and the atmospheric pressure is made in order to
increase the supercharge flow during cold starts. It is possible to alter the supercharge flow value by
adding a flow offset with the aid of the diagnostic tool
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(7) Knocking Control
A. Resetting the pilot injection
The knocking control is used to reset the pilot injection flow in closed loop for each injector. This
method allows the correction of any injector deviations over a period of time. The principle of use of the
knocking control is based on the detection of the combustion noises.
The sensor is positioned in such a way as to receive the maximum signal for all the cylinders. The raw
signals from the knock sensor are processed to obtain a variable which quantifies the intensity of the
combustion. This variable, known as the ratio, consists of the ratio between the intensity of the
background noise and the combustion noise.
A first window is used to establish the background noise level of the knocking control signal for
each cylinder. This window must therefore be positioned at a moment when there cannot be any
combustion.
The second window is used to measure the intensity of the pilot combustion. Its position is such
that only the combustion noises produced by the pilot injection are measured . It is therefore
placed just before the main injection. 1.
2.
The knock sensor does not allow any evaluation of the quantity injected. However, the pulse value will
be measured when the injector starts injection and this pulse value is called the MDP (Minimum Drive
Pulse). On the basis of this information, it is possible to efficiently correct the pilot flows. The pilot
injection resetting principle therefore consists of determining the MDP, in other words the pulse
corresponding to the start of the increase in value of the ratio (increase of vibration due to fuel
combustion).
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This is done periodically under certain operating conditions. When the resetting is finished, the new
minimum pulse value replaces the value obtained during the previous resetting. The first MDP value is
provided by the C3I. Each resetting then allows the closed loop of the MDP to be updated according to
the deviation of the injector.
B. Detection of leaks in the cylinders
The accelerometer is also used to detect any injector which may have stuck open. The detection
principle is based on monitoring the ratio. If there is a leak in the cylinder, the accumulated fuel self-
ignites as soon as the temperature and pressure conditions are favorable (high engine speed, high
load and small leak).
This combustion is set off at about 20 degrees before TDC and before main injection.
The ratio therefore increases considerably in the detection window. It is this increase which allows the
leaks to be detected. The threshold beyond which a fault is signaled is a percentage of the maximum
possible value of the ratio.
Because of the severity of the recovery process (engine shut-down), the etection must be extremely
robust.
An increase in the ratio can be the consequence of various causes:
Pilot injection too much
Main combustion offset
Fuel leak in the cylinder -
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If the ratio becomes too high, the strategy initially restricts the pilot injection flow and retards the main
injection. If the ratio remains high despite these interventions, this shows that a real leak is present, a
fault is signaled and the engine is shut down.
C. Detection of an accelerometer fault
This strategy permits the detection of a fault in the sensor or in the wiring loom connecting the sensor
to the ECU.
It is based on detection of the combustion. When the engine is idling, the detection window is set too
low for the combustion caused by the main injection. If the ratio increases, this shows that the knock
sensor is working properly, but otherwise a fault is signaled to indicate a sensor failure. The recovery
modes associated with this fault consist of inhibition of the pilot injection and discharge through the
injectors.
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Electric throttle
bodyAccelerator
pedal
moduleD20DTR
ECU
(9) EGR control
A. Overview
The EGR (Electric-Exhaust Gas Recirculation) valve reduces the NOx emission level by recirculating
some of the exhaust gas to the intake system.
To meet Euro-V regulation, the capacity and response rate of E-EGR valve in D20DTR engine have
been greatly improved. The EGR cooler with high capacity reduces the Nox, and the bypass valve
reduces the CO and HC due to EGR gas before warming up.
Also, the engine ECU adjusts the E-EGR opening by using the air mass signal through HFM sensor. If
the exhaust gas gets into the intake manifold when the EGR valve is open, the amount of fresh air
through HFM sensor should be decresed.
B. Components
E-EGR cooler
Coolant
temperature
sensorOxygen sensor
HFM (intake
air
temperature)
Crankshaft
position
sensorE-EGR valve
T-MAP
sensor
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1. CRUISE CONTROL SWITCH
The cruise control is an automatic speed control system that maintains a desired driving speed without
using the accelerator pedal.
The vehicle speed must be greater than 36 km/h to engage the cruise control. This feature is
especially useful for motorway driving.
The cruise control system is a supplementary system, which helps the driver to drive the vehicle at
a desired speed without using the accelerator pedal under the traffic condition where the vehicle-to-
vehicle distance meets the legal requirement.
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5) Normal Cancellation of the Cruise Control
The cruise control system will be canceled when one or more items of the following conditions are
applied;
Keep the main cruise control switch in the neutral position when not using the cruise control.When the brake pedal is depressed.
When the cruising speed is downed less than 38 km/h.
When the OFF switch is operated by pulling the cruise control lever (Type A) or by pushing the ON-
OFF switch of the cruise control lever (Type B).
When ESP is activated.
When applying the parking brake when driving.
When using the clutch in order to shift (M/T only).
And the cruise control system can be operated again in driving state. 1.
2.
3.
4.
5.
6.
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Transponder
3. VERIFICATION OF KEY
1) Verification
The immobilizer system prevents the vehicle theft by allowing only the authorized key to start the
engine. The transponder inside the key communicates with the immobilizer installed in the key box,
and the system permits the engine to start after confirming the encrypted coding from the engine ECU.
In the following cases, a driver may be unable to start the vehicle with the immobilizer.The immobilizer unit transmits
the encrypted code to the
transponder. (2)
The transponder sends an encrypted signal to the unit as a response.
The transmitted code is changed to an encrypted signal in the unit.
The system compares the signal from transponder and the encrypted signal in immobilizer unit. (3)
(4)
(5)
When two or more immobilizer keys come into contact with (each) other(s).
When the key is close to any device sending or receiving electromagnetic fields or waves.
When the key is close to any electronic or electric devices such as lightening equipment,
security keys or security cards.
When the key is close to a magnetic or metal object or a battery. -
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Immobilizer Unit