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03-14
(6) Low Pressure System Pressure Test
Inspection procedure ▶
All wirings/connectors and fuel lines should be
connected and the engine should work
properly.
Prepare a special tool for low pressure test
and clean it thoroughly to prevent foreign
materials from entering. 1.
2.
Disconnect the key connector for fuel filter connection, and connect both connectors to the fuel filter
and hose. 3.
Start the engine and check visually for clogged low pressure fuel system, excessive air or air entry.
If the fuel flow is not sufficient or air is in the fuel, repair the leak area. 4.
5.
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03-18
3. CAUTIONS FOR DI ENGINE
1) Cautions for DI Engine
This chapter describes the cautions for DI engine equipped vehicle. This includes the water separation
from engine, warning lights, symptoms when engine malfunctioning, causes and actions.
DI Engine 1.
Comparatively conventional diesel engines, DI engine controls the fuel injection and timing electrically,
delivers high power and reduces less emission..
System Safety Mode 2.
When a severe failure has been occurred in a vehicle, the system safety mode is activated to protect the
system. It reduces the driving force, restricts the engine speed (rpm) and stops engine operation. Refer
to "Diagnosis" section in this manual.
Engine CHECK Warning Lamp 3.
The Engine CHECK warning lamp on the instrument cluster comes on when the fuel or
major electronic systems of the engine are not working properly. As a result, the
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8800a00047009a009b0088009300930055>
Water Separator Warning Lamp 4.
When the water level inside water separator in fuel filter exceeds a certain level (approx.
45 cc), this warning light comes on and buzzer sounds.
Also, the driving force of the vehicle decreases (torque reduction). If these conditions
occur, immediately drain the water from fuel filter.
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03-20
(2) Di engine and its expected problems and remedies can be caused by
water in fuel
System supplement against paraffin separation ▶
In case of Diesel fuel, paraffin, one of the elements, can be separated from fuel during winter and then
can stick on the fuel filter blocking fuel flow and causing difficult starting finally. Oil companies supply
summer fuel and winter fuel by differentiating mixing ratio of kerosene and other elements by region and
season. However, above phenomenon can be happened if stations have poor facilities or sell improper
fuel for the season. In case of DI engine, purity of fuel is very important factor to keep internal
preciseness of HP pump and injector.
Accordingly, more dense mesh than conventional fuel filter is used. To prevent fuel filter internal clogging
due to paraffin separation, SYMC is using fuel line that high pressure and temperature fuel injected by
injector returns through fuel filter to have an effect of built-in heater (see fuel system).
System supplement and remedy against water in fuel ▶
As mentioned above, some gas stations supply fuel with excessive than specified water. In the
conventional IDI engine, excessive water in the fuel only causes dropping engine power or engine
hunting. However, fuel system in the DI engine consists of precise components so water in the fuel can
cause malfunctions of HP pump due to poor lubrication of pump caused by poor coating film during high
speed pumping and bacterization (under long period parking). To prevent problems can be caused by
excessive water in fuel, water separator is installed inside of fuel filter. When fuel is passing filter, water
that has relatively bigger specific gravity is accumulated on the bottom of the filter.
Water drain from water separator ▶
If water in the separator on the fuel filter exceeds a certain level, it will be supplied to HP pump with fuel,
so the engine ECU turns on warning lamp on the meter cluster and buzzer if water level is higher than a
certain level.
Due to engine layout, a customer cannot easily drain water from fuel filter directly, so if a customer
checks in to change engine oil, be sure to perform water drain from fuel filter.
Water
separator
To separate the water from the fuel filter,
remove the fuel filter assembly first.
Page 100 of 751
03-232210-01
Accelerator pedal position
sensor
Detecting driver's intention
for speed up/down
Fuel rail assembly
Relieving the pulsation.
Measuring the fuel pressure.
Distributing the fuel to injectors.
Fuel filter assembly
Supplying clean fuel/fuel
heating/water separation by
priming pump
Plunger type HP pump (1,800 bar)
Vane type LP pump (6 bar)
T-MAP sensor
Measuring booster pressure
and temperature
High pressure pump
Generating high pressurized fuel and
supplying it according to engine rpm,
required volume, required pressure
Page 101 of 751

03-24
2) Fuel System Flow Diagram
The fuel from the fuel tank is supplied to the fuel heater of fuel filter/priming pump and then low pressure
generated by the low pressure pump (built into HP pump) is transmitted to the HP pump.
The fuel pressure at the HP pump is controlled by the IMV valve, and the maximum allowed pressure is
1,800 bar. The compressed fuel at the fuel pump is delivered to the rail, and injected by the injectors
according to the injection signals. The injection method is the same with the conventional method; Fuel
return by backleak which operates the needle valve.
The major difference is that the fuel return line is connected to the fuel filter inlet port, not the HP pump
venturi.
The pressure from the high pressure pump is increased to 1,800 bar from 1,600 bar, and the pump is now
installed to the cylinder head (cylinder block for previous model). The fuel pressure is generated by the
operation of intake camshaft and gears. The specifications for the IMV valve and the fuel temperature
sensor are not changed.
Page 188 of 751
14-4
2. CAUTIONS
1) Standard pattern of soot accumulation
Abnormal Soot Accumulation ▶
Normal Soot Combustion ▶
Cautions to protect the catalyst filter ▶
Use the designated fuel only.
Observe the recommended service intervals of engine oil.
Check the engine oil level frequently and add if necessary.
Do not idle the vehicle unnecessarily.
Do not turn off the engine while the vehicle is running.
Do not shift the gear selector lever to neutral when going downhill.
Do not use improper engine oil or fuel additives.
Do not drive for a long time when the warning lamp is illuminated.
Make sure no flammable material, such as dry grass or tissue paper, contacts with the catalyst filter
while the vehicle is parked.
For the vehicles used in urban traffic, driving on the expressways for more than 1 hour at least once
per week is needed so that the PM inside CDPF isn't collected to one side only. -
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-
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14-152412-02
2) Collecting PM of DPF
There is a filter installed in the DPF and the PM filtered by this filter is burned (regeneration) when the
temperature of exhaust gas is increased due to post-injection. The filter has a honeycomb-like structure
to capture the particulate matter and the inlet and outlet of each channel are closed alternatively. Once
the exhaust gas enters to the inlet of a channel, it is released from the outlet of the adjacent channel
through the porous wall because of the closed outlet of the first channel, and the PM is collected in the
first channel.
[Collecting PM of CDPF]
Normally, when the driving distance becomes approx. 600 to 1,200 km, enough amount of soot to
be burned is filtered and accumulated in the CDPF. The ECU increases the amount of fuel post-
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9a009b0047008e0088009a0047009c00970047009b00960047>600°C, so that the soot is
burned. The soot is burned for 15 to 20 minutes (may differ by conditions).
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15-18
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.