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SsangYong Actyon Sports II. Manual - part 55

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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.

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.

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.

(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.

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:

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.

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

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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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