SsangYong Korando III (2010 year). Service manual — part 74

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This is done periodically under certain operating conditions. When the resetting is finished, the new

minimum pulse value replaces the value obtained during the previous resetting. The first MDP value is

provided by the C3I. Each resetting then allows the closed loop of the MDP to be updated according to

the deviation of the injector.

b. Detection of leaks in the cylinders

The accelerometer is also used to detect any injector which may have stuck open. The detection

principle is based on monitoring the ratio. If there is a leak in the cylinder, the accumulated fuel self-

ignites as soon as the temperature and pressure conditions are favorable (high engine speed, high load

and small leak).

This combustion is set off at about 20 degrees before TDC and before main injection.

The ratio therefore increases considerably in the detection window. It is this increase which allows the

leaks to be detected. The threshold beyond which a fault is signaled is a percentage of the maximum

possible value of the ratio.

Because of the severity of the recovery process (engine shut-down), the etection must be extremely

robust.

An increase in the ratio can be the consequence of various causes:

Pilot injection too much

Main combustion offset

Fuel leak in the cylinder

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If the ratio becomes too high, the strategy initially restricts the pilot injection flow and retards the main

injection. If the ratio remains high despite these interventions, this shows that a real leak is present, a

fault is signaled and the engine is shut down.

c. Detection of an accelerometer fault

This strategy permits the detection of a fault in the sensor or in the wiring loom connecting the sensor to

the ECU.

It is based on detection of the combustion. When the engine is idling, the detection window is set too low

for the combustion caused by the main injection. If the ratio increases, this shows that the accelerometer

is working properly, but otherwise a fault is signaled to indicate a sensor failure. The recovery modes

associated with this fault consist of inhibition of the pilot injection and discharge through the injectors.

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HFM

Accelerator pedal

Coolant

temperature

(4) Swirl control

a. Overview

Variable swirl valve

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The strong swirl caused by intake air is important element for anti-locking function in diesel engine. The

swirl control valve partially closes the intake port to generate the swirl according to the engine conditions.

When the engine load is in low or medium range, the swirl could not be generated because the air flow

is slow. To generate strong swirl, there are two passages in intake manifold, and one of them has the

valve to open and close the passage. When the valve closes the passage, the air flow through the

another passage will be faster, and the strong swirl will be generated by the internal structure of the

passage. This swirl makes the better mixture of air and fuel, eventually the combustion efficiency in

combustion chamber could be improved. This provides the enhanced fuel consumption, power and

EGR ratio.

Components

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D20DTF ECU

Crankshaft

position sensor

Variable swirl

valve

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b. Input/Output for variable swirl valve

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c. Types of swirl

Swirl: One cylinder has two intake air ports, one is set horizontally

and the other one is set vertically. Swirl is the horizontal air flows in

cylinder due to the horizontal intake air ports.

Tumble: Tumble is the vertical air flows in cylinder due to the vertical

intake air port

Squish: Squish is the air flows due to the piston head. Normally, this

is appears at the final process of compression. In CRDi engine, the

piston head creates the bowl type squish.

d. Swirl control

In DI type diesel engine, the liquefied fuel is injected into the cylinder directly. If the fuel is evenly

distributed in short period, the combustion efficiency could be improved. To get this, there should be

good air flow in cylinder. In general, there are two intake ports, swirl port and tangential port, in each

cylinder. The swirl port generates the horizontal flow and the tangential port generates the longitudinal

flow.

In low/mid load range, the tabgential port is closed to increase the horizontal flow. Fast flow decreases

the PM during combustion and increases the EGR ratio by better combustion efficiency.