2012 SSANGYONG KORANDO fuel

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c. Fuel Injection Control
Injection control is used in order to determine the characteristics of the pulse which is sent to the
injectors.
Injection control consists as below.
Injection timing
Injection volume
Translating fuel injection timing and injection volume into values which can be interpreted by the
injector driver. -
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Main injection timing control ▶
The pulse necessary for the main injection is determined as a function of the engine speed and of the
injected flow.
The elements are:
A first correction is made according to the air and coolant temperatures.
This correction makes it possible to adapt the timing to the operating temperature of the engine.
When the engine is warm, the timing can be retarded to reduce the combustion temperature and
polluting emissions (NOx). When the engine is cold, the timing advance must be sufficient to allow
the combustion to begin correctly.
A second correction is made according to the atmospheric pressure.
This correction is used to adapt the timing advance as a function of the atmospheric pressure and
therefore the altitude.
A third correction is made according to the coolant temperature and the time which has passed since
starting.
This correction allows the injection timing advance to be increased while the engine is warming up
(initial 30 seconds). The purpose of this correction is to reduce the misfiring and instabilities which are
liable to occur after a cold start.
A fourth correction is made according to the pressure error.
This correction is used to reduce the injection timing advance when the pressure in the rail is higher
than the pressure demand.
A fifth correction is made according to the rate of EGR.
This correction is used to correct the injection timing advance as a function of the rate of exhaust gas
recirculation.
When the EGR rate increases, the injection timing advance must in fact be increased in order to
compensate for the fall in termperature in the cylinder. -
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During starting, the injection timing must be retarded in order to position the start of combustion close to
the TDC. To do this, special mapping is used to determine the injection timing advance as a function of
the engine speed and of the water temperature.

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Pilot injection timing control ▶
The pilot injection timing is determined as a function of the engine speed and of the total flow.
The elements are:
A first correction is made according to the air and coolant temperatures. This correction allows the
pilot injection timing to be adapted to the operating temperature of the engine.
A second correction is made according to the atmospheric pressure. This correction is used to adapt
the pilot injection timing as a function of the atmospheric pressure and therefore the altitude. -
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d. Fuel Control
1. Main Flow Control
The main flow represents the amount of fuel injected into the cylinder during the main injection. The pilot
flow represents the amount of fuel injected during the pilot injection.
The total fuel injected during 1 cycle (main flow + pilot flow) is determined in the following manner.
When the driver depress the pedal, it is his demand which is taken into account by the system in order
to determine the fuel injected.
When the driver release the pedal, the idle speed controller takes over to determine the minimum fuel
which must be injected into the cylinder to prevent the enigne from stalling. ▶
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It is therefore the greater of these 2 values which is retained by the system. This value is then compared
with the lower flow limit determined by the ESP system.
As soon as the injected fuel becomes lower than the flow limit determined by the ESP system, the
antagonistic torque (engine brake) transmitted to the drive wheels exceeds the adherence capacity of
the vehicle and there is therefore a risk of the drive wheels locking.
The system thus chooses the greater of these 2 values (main flow & pilot flow) in order to prevent any
loss of control of the vehicle during a sharp deceleration.
As soon as the injected fuel becomes higher than the fuel limit determined by the ASR trajectory control
system, the engine torque transmitted to the wheels exceeds the adhesion capacity of the vehicle and
there is a risk of the drive wheels skidding. The system therefore chooses the smaller of the two values
in order to avoid any loss of control of the vehicle during accelerations.
The anti-oscillation strategy makes it possible to compensate for fluctuations in engine speed during
transient conditions. This strategy leads to a fuel correction which is added to the total fuel of each
cylinder.
The main fuel is obtained by subtracting the pilot injection fuel from the total fuel.
A mapping determines the minimum fuel which can control an injector as a function of the rail pressure.
As soon as the main fuel falls below this value, the fuel demand changes to 0 because in any case the
injector is not capable of injecting the quantity demand. A switch makes it possible to change over from the supercharge fuel to the total fuel according to the
state of the engine.
Until the stating phase has finished, the system uses the supercharged fuel.
Once the engine changes to normal operation, the system uses the total fuel. -
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2. Driver Demand
The driver demand is the translation of the pedal position into the fuel demand. It is calculated as a
function of the pedal position and of the engine speed. The driver demand is filtered in order to limit the
hesitations caused by rapid changes of the pedal position. A mapping determines the maximum fuel
which can be injected as a function of the driver demand and the rail pressure. Since the flow is
proportional to the injection time and to the square root of the injection pressure, it is necessary to limit
the flow according to the pressure in order to avoid extending the injection for too long into the engine
cycle. The system compares the driver demand with this limit and chooses the smaller of the 2 values.
The driver demand is then corrected according to the coolant temperature. This correction is added to
the driver demand.

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3. 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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4. 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.
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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5. Pilot Flow Control
The pilot flow represents the amount of fuel injected into the cylinder during the pilot injection. This
amount is determined according to the engine speed and the total flow.
A first correction is made according to the air and water temperature.
This correction allows the pilot flow to be adapted to the operating temperature of the engine. When
the engine is warm, the ignition time decreases because the end-of-compression temperature is
higher. The pilot flow can therefore be reduced because there is obviously less combustion noise
when the engine is warm.
A second correction is made according to the atmospheric pressure. -
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During starting, the pilot flow is determined on the basis of the engine speed and the coolant
temperature.
6. Cylinder Balancing Strategy
Balancing of the point to point flows ▶
The pulse of each injector is corrected according to the difference in instantaneous speed measured
between 2 successive injectors.
The instantaneous speeds on two successive injections are first calculated.
The difference between these two instantaneous speeds is then calculated.
Finally, the time to be added to the main injection pulse for the different injectors is determined. For each
injector, this time is calculated according to the initial offset of the injector and the instantaneous speed
difference.
Detection of an injector which has stuck closed ▶
The cylinder balancing strategy also allows the detection of an injector which has stuck closed. The
difference in instantaneous speed between 2 successive injections then exceeds a predefined threshold.
In this case, a fault is signaled by the system.

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e. MDP Learning Control
MDP (Minimum Drive Pulse ) refers to the
minimum power supply pulse for injection which
the injector can perform. It is possible to control
the fuel volume for each injector accurately
through correct learning for the MDP value. The
basic process of MDP learning is that the pulse
slightly higher than MDP is supplied and then (b)
the vibration generated from the cylinder is
detected. The knock sensor detects the vibration
from the engine after a small volume of fuel is
injected. And the time interval between the points
of injection and vibration is measured so that
MDP can be learned. MDP learning is helpful to
prevent engine vibration, high emission and
power reduction through performing calibration
for the old injectors. During MDP learning, a little
vibration and noise can be occur for a while. This
is because the fuel pressure is increased
instantaneously and the exact injection value is
not input, so that the exact engine vibration
timing can be detected.

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(3) Accelerometer Control
a. Resetting the pilot injection
The accelerometer 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
accelerometer 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 accelerometer 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 accelerometer 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 accelerometer 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 accelerometer
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.