SsangYong Stavic / SsangYong Rodius (2005 year). Manual - part 143

DI08-9

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ENGINE CONTROL SYSTEM

DI ENG SM - 2004.9

Control Function of ECU

• 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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ENGINE CONTROL SYSTEM

DI ENG SM - 2004.9

ECU - Removal and Installation

1. Flip up the front passenger’s seat and remove the ECU

cover nuts.

2. Remove the ECU bracket nuts.

3. Unscrew the ECU connect bolt and remove the ECU

assembly.

4. Install in the reverse order of removal.

5. Backup the below data with SCAN-100 when replacing

the ECU.

- Current ECU data

- Vehicle Identification Number (VIN)

- Variant coding data

- Then, input the data into new ECU. For immobilizer

equipped vehicle, additional coding operation is
necessary.

DI08-11

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ENGINE CONTROL SYSTEM

DI ENG SM - 2004.9

FUEL PRESSURE CONTROL

Fuel Pressure Control Elements

Pressure control consists of 2 principle modules.

• Determines rail pressure according to engine operating conditions.

• Controls IMV to make the rail pressure to reach to the required value.

Pressure in the fuel rail is determined according to engine speed and load on the engine. The aim is to adapt the
injection pressure to the engine’s requirements.

• 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.

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.

Fuel Pressure Control

Rail pressure is controlled by closed loop regulation of IMV. A mapping system – open loop – determines the current
which needs to be sent to the actuator in order to obtain the flow demanded by the ECU. The 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.

Flow demand

Engine speed

Measured rail

pressure

Open

IMV current

IMV

Current

PIG

governor

Error

Correction

Rail pressure

demand

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ENGINE CONTROL SYSTEM

DI ENG SM - 2004.9

FUEL INJECSTION CONTROL

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.

- a reference tooth (CTP)

- the delay between this tooth and the start of the pulse (Toff)

- the pulse time (Ton)

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.

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. This requirement only concerns the starting phase, since once the engine has started the system
must re-use the mapping and the corrections described previously.

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.

During the starting phase, the pilot injection timing is determined as a function of the engine speed and of the coolant
temperature.