Idle Speed Controller; Flow Limitation; Pilot Flow Control - SSANGYONG 2004 Rexton 2.7XDi Workshop Manual

DI08-16

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,
the accelerated idle speed is activated to prevent the engine from stalling when operating in degraded mode.
- It is possible to increase or to reduce the required idle speed with the aid of the diagnostic tool.
• 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.

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 these 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.

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.
This correction is used to adapt the pilot flow according to the atmospheric pressure and therefore the altitude.
During starting, the pilot flow is determined on the basis of the engine speed and the coolant temperature.
CHANGED BY
EFFECTIVE DATE
AFFECTED VIN
ENGINE CONTROL SYSTEM
DI ENG SM - 2004.4