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15-230000-00
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 -
-
-
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 knock sensor
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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Load Engine speedSwirl
valveAmount of
swirlRemarks
Low speed,
Low loadbelow 3,000 rpm Closed HeavyIncreased EGR ratio, better air-fuel
mixture (reduce exhaust gas))
High speed,
High loadover 3,000 rpm Open LightIncrease charge efficiency, higher
engine power
The variable swirl valve actuator operates when
turning the ignition switch ON/OFF position to
open/close the swirl valve. In this period, the soot
will be removed and the learning for swirl valve
position is performed.
Swirl: This is the twisted (radial) air flow along the cylinder wall during the intake stroke. This
stabilizes the combustion even in lean air-fuel mixture condition.
Swirl valve
E. Features
Swirl and air intake efficiency
To generate the swirl, the intake port should be serpentine design. This makes the resistance in air
flow. The resistance in air flow in engine high speed decreases the intake efficiency. Eventually, the
engine power is also decreased, Thus, the swirl operation is deactivated in high speed range to
increase the intake efficiency.
Relationship between swirl and EGR
To reduce Nox, it is essential to increase EGR ratio. However, if EGR ratio is too high, the PM also
could be very higher. And, the exhaust gas should be evenly mixed with newly aspired air. Otherwise,
PM and CO are dramatically increased in highly concentrated exhaust gas range and EGR ratio
could not be increased beyond a certain limit. If the swirl valve operates in this moment, the limit of
EGR ratio will be higher. -
-
F. Relationship between swirl and fuel injection pressur
The injector for DI engine uses the multi hole design. For this vehicle, there are 8 holes in injector. If the
swirl is too strong, the injection angles might be overlapped and may cause the increased PM and
insufficient engine power. Also, if the injection pressure is too high during strong swirl, the injection
angles might be overlapped. Therefore, the system may decreases the fuel injection pressure when the
swirl is too strong.
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15-48
Rear EGT sensor:
Measure DPF temp
Diff. pres. sensor:
Measure pressure
between front side and
rear side of CDPFElectronic throttle
body: Control intake
air mass
ECU (DCM 3.7)
Injector: Control post
injection
D. Operation process
When the differential pressure sensor detects the pressure difference between the front and the rear
side of CDPF, the sensor sends signal indicating the soot is accumulated and the post injection is
performed to raise the temperature of exhaust gas. The amount of fuel injected is determined according
to the temperature of exhaust gas detected by the rear temperature sensor. If the temperature is below
600°C, the amount of fuel injected is increased to raise the tem
perature. If the temperature is over
600°C, the amount of fuel injected is decreased or not controlled. When the engine is running in
low load range, the amount of post injection and the amount of intake air are controlled. It is to raise the
temperature by increasing the amount of fuel while decreasing the amount of intake air.
Front EGT sensor:
Measure DOC temp
T-MAP sensor
Intake air
mass
Exceed PM
limitBooster
pressure/
temperaturePost injection
Control intake
air mass
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01-10
1. OVERVIEW
▶DC 5-Speed Automatic Transmission
DCAG 5-speed automatic transmission is an electronically controlled 5-speed transmission with a lockup
clutch in the torque converter. The ratios for the gears are realized by three planetary gear sets. The 5th
gear is designed with a step-up ratio of 0.83 as an overdrive. The selector lever is controlled by
electronically and mechanically. The gears are shifted by the corresponding combination of three
hydraulically actuated multiple-disc brakes, three hydraulically actuated multiple-disc clutches and two
mechanical one-way clutches. This electronically controlled automatic transmission adjusts the operating
pressure to provide proper shifting in relation to engine power. This function improves shifting quality
significantly. And, the driver can select "S" (Standard) mode or "W" (Winter) mode according to the driving
conditions. This automatic transmission provides two gears even during reverse driving. The internal
sensors and controls are connected to TCU by cylindrical 13-pin connector.
DCAG 5-speed automatic transmission offers the following advantages:
Improved shifting quality
More gears
Extended working life and reliability
Reduced fuel consumption 1.
2.
3.
4.
DC A/T Assembly Number
(With T/Converter)
A/T Serial Number
DC A/T Variant Number 1.
2.
3.DC A/T Assembly Number
(With T/Converter)
Base model AT type
A/T Serial Number 1.
2.
3.