engine SSANGYONG NEW ACTYON SPORTS 2012 Service Manual

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b. Pilot Injection
Injection before main injection. Consists of 1st and 2nd pilot injection, and Pre-injection
Inject a small amount of fuel before main injection to make the combustion smooth. Also, called
as preliminary injection or ignition injection. This helps to reduce Nox, engine noise and vibration,
and to stabilize the idling.
The injected fuel volume is changed and stopped according to the coolant temperature and
intake air volume.
Pilot injection is much earlier than main injection due to higher engine rpm
Too small injection volume (insufficient injection pressure, insufficient fuel injection volume
in main injection, engine braking)
System failure (fuel system, engine control system) -
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Pilot injection
Main injection
Combustion pressure with pilot injection
Combustion pressure without pilot injection 1.
2.
1a.
2b. Stop conditions
Combustion pressure characteristic curve for pilot injection ▶

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c. Main Injection
The power of the vehicle is determined by the main fuel injection volume.
Main injection calculates the fuel volume based on pilot injection. The calculation uses the value
for accelerator pedal position, engine rpm, coolant temperature, intake air temperature, boost
pressure, boost temperature and atmospheric pressure etc.
d. Post Injection
Injection after main injection. Consists of After injection, Post 1, Post 2 injection.
Post injection reduces PM and smoke from exhaust gas. No actual output is generated during
these injections, instead, fuel is injected to the unburned gas after main injection to enable fuel
activation. The PM amount in the emission and smoke can be reduced through these processes.
Only up to 5 types of injections can be performed within 1 cycle. If these 7 injections are all
performed, fuel economy and emission performance becomes poor.

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(3) Fuel Pressure Control
Fuel pressure is controlled by IMV opening according to the calculated value by ECU.
Pressure in the fuel rail is determined according to engine speed and load on the engine. ▶
When engine speed and load are high
The degree of turbulence is very great and the fuel can be injected at very high pressure in
order to optimize combustion.
When engine speed and load are low
The degree of turbulence is low. If injection pressure is too high, the nozzle's penetration will
be excessive and part of the fuel will be sprayed directly onto the sides of the cylinder,
causing incomplete combustion. So there occurs smoke and damages engine durability. -
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Fuel pressure is corrected according to air temperature, coolant temperature and atmospheric
pressure and to take account of the added ignition time caused by cold running or by high
altitude driving. A special pressure demand is necessary in order to obtain the additional flow
required during starts. This demand is determined according to injected fuel and coolant
temperature.
Open loop determines the current which needs to be sent to the actuator in order to obtain the
flow demanded by the ECU. ▶
Closed loop will correct the current value depending on the difference between the pressure
demand and the pressure measured. ▶
If the pressure is lower than the demand, current is reduced so that the fuel sent to the high
pressure pump is increased.
If the pressure is higher than the demand, current is increased so that the fuel sent to the high
pressure pump is reduced. -
-Fuel Pressure ▶

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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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(4) Injection Timing Control
Injection timing is determined by the conditions below. ▶
Coolant temperature
Hot engine - Retarded to reduce Nox
Cold engine - Advanced to optimize the combustion 1.
Atmospheric pressure
Advanced according to the altitude 2.
Warming up
Advanced during warming up in cold engine 3.
Rail pressure
Retarded to prevent knocking when the rail pressure is high 4.
EEGR ratio
Advanced to decrease the cylinder temperature when EGR ratio increases 5.
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. -
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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. -
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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.
A. 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.
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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(5) Fuel Control
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.

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B. 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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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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F. 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.
G. 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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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.
(6) MDP Learning Control
A. MDP Learning
When the pulse value that the injector starts injection is measured, it is called minimum drive pulse
(MDP). Through MDP controls, can correct pilot injections effectively. Pilot injection volume is very
small, 1 to 2 mm/str, so precise control of the injector can be difficult if it gets old. So there
needs MDP learning to control the very small volume precisely through learning according to
getting older injectors.
Control the fuel injection volume precisely by MDP learning even for the old injector.
ECU corrects the pilot injection effectively by MDP control.
MDP learning is performed by the signal from knock sensor. -
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- The system measures the pulse at initial injection to reduce the engine vibration.
B. Purpose of MDP learning

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C. Learning Conditions
Idle MDP learning Drive MDP learning
Coolant temperatureover 60℃ over 60℃
Vehicle speedIdling over 50km/h (over 5 seconds)
Engine rpm2,000 to 2,500 rpm
Fuel temperature0 < Fuel temperature < 80℃
Learning2 times for each cylinder (every
5 seconds)2 times for each cylinder
(every 5 seconds)
If MDP learning is not properly performed, engine vibration and injection could be occurred.
MDP learning should be performed after replacing ECU, reprogramming and replacing
injector. -
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D. Injector characteristic curve for rail pressure