SsangYong Korando III (2010 year). Service manual — part 367

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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

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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

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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.