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5) Guidelines on Engine Service
(1) Cautions before service works
Make sure to disconnect the negative (-) cable from the battery to prevent any damage to electric
systems.
Make sure to clean the working area and to prepare the necessary tools before service works.
Always place the ignition switch to OFF position if not required. Otherwise, there could be
unexpected damage to electric devices or personal injuries due to short-circuit.
To prevent the foreign material from entering into the fuel injection system, completely seal the inlets
of HP pump, fuel hoses and high pressure pipes.
To remoev the engine, use the dedicated equipments such as engine jack, transmission jack, engine
stand and engine crane. -
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(2) Engine and accessories
When disassembling the engine, related parts (bolts, gaskets, etc.) should be stored as a set.
Clean the components completely with engine oil before assembling if needed.
Fully drain the engine oil, coolant and fuel from the vehicle and seal the inlets with the plugs before
removing the engine.
All the interference should be eliminated before removing the engine. -
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(3) Electric devices
To prevent any damage to electric systems, make sure to disconnect the negative (-) cable from the
battery and place the ignition switch to OFF position before servicing.
Use only the specified parts with same ratings when replacing the electric devices. Check the
grounds and connections for looseness. -
- To prevent the personal injuries and vehicle damages that can be caused by mistakes during service
and to provide the optimized performance and safety after service works, the service technicials must
keep the basic cautions and service guidelines below. These could be easily forgotten during service
works.
Engine has a lot of precise components. The specified tightening torque and correct procedures should
be kept during service works. And, the working area is always clean and well prepared.
Extraordinary care should be taken when servicing the electric systems. Currently, the engine uses a lot
of electric devices. Short circuit and poor contact may cause the low engine performance, incomplete
combustion and other abnormalities.
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1719-02 Swirl control valve
Operates variably in accordance with the engine
load and rpm.
* For more information, refer to Chapter "Engine
Control".
1719-01 Intake manifold
Passage for intake air during the operation of
variable swirl valve
1719-16 Electric throttle body
* For more information, refer to Chapter "Engine
Control".
1. OVERVIEW
The intake system for D20DTF engine is equipped with an electric throttle body which includes a flap.
This flap is controlled by an electrical signal to cut off the intake air entering to the engine when the
ignition switch is turned off. To be sure to get the optimized swirl in intake manifold, the swirl valve and
dual type port have been adopted. And, the improved HFM sensor has been adopted to control the
intake air volume more precisely.
2. COMPONENTS
2330-01 Intercooler assembly
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Load Engine speed Swirl
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 valve
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.
3) 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. -
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4) Relationship between swirl and fuel injection pressure
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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2. CAUTIONS
Do not park the vehicle on flammable materials, such as grass, leaves and carpet.
Do not touch the catalyst or the exhaust gas ignition system when the engine is running.
If a misfire occurs in the combustion chamber or the emission of pollutant exceeds the specified
level, the catalyst can be damaged.
When servicing or replacing components of the exhaust system, makes sure that the components
are positioned at regular intervals from all other parts of the under body.
Be careful not to damage the exhaust system when lifting the vehicle from its side.
All components and body parts of the engine exhaust system should be inspected for crack,
damage, air hole, part loss and incorrect mounting location. Also check for any deformation which
can result in exhaust gas drawn into the vehicle.
Make sure that the exhaust pipe is cooled down sufficiently before working on it because it is still hot
right after the engine is stopped.
Wear protective gloves when removing the exhaust pipe. -
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2. INSPECTION
1) Alternator Output Test
Item How to check DTC set value / Action
Output
current
B terminal
current
Rotor
coil
resistance
L terminal
voltage
Disconnect the cable connected to the B
terminal on the alternator. Connect one end
of the ammeter to the B terminal and the
other end to the cable connected to the B
terminal.
Measure the maximum output value.
(Maintain the engine speed between 2,500
and 3,000 rpm.)
(Turn the headlamp and all the electrical
switches on.) 1.
2.Pass: If the measured current is 45 A
or higher.
Fail: If the measured current is less
than 45 A.
Check the current of the B terminal. -
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Move the gear selector lever to the
neutral position.
Maintain the engine speed at 2,500 rpm
with the vehicle unloaded.
(Turn all the electrical switches off.) 1.
2.Open circuit: If the measured
current is 5 A or higher. -
Disconnect the negative cable from the
battery.
Remove the B terminal and turn off the
ignition switch.
Measure the resistance between the L and F
terminals with an ohmmeter. 1.
2.
3.Pass: If the measured resistance is
Faulty rotor coil or slip ring: If the
measured resistance is less than 3
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Connect the B terminal wiring.
Measure the voltage with the engine running. 1.
2.Specification: 12.5 V to 14.5 V
Faulty IC regulator or field coil: If
the measured voltage is 14.5 V or
higher. -
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Disconnect the negative battery cable.
Connect the negative cable again after connecting the ammeter. -
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2) Troubleshooting for Alternator
Item Cause Action
Overcharged battery Defective alternator voltage regulator Replace
defective alternator detection wiring Repair or replace
Discharged battery Loose alternator drive belt Adjust the belt tension or replace
Poor connection of related circuit or
open circuitRetighten the loose connection or
repair open circuit
Defective alternator voltage regulator Replace
Terminated battery Replace
Defective ground Repair
Charge warning lamp
does not come on when
turning on ignition switch
with engine stoppedDefective alternator voltage regulator Replace
Open circuit in charge warning lamp,
fuse or wiringReplace or repair the charge
warning lamp or fuse
Defective ignition switch Replace
Defective ground of alternator circuit Repair
Charge warning lamp
does not go off after
starting engineDefective alternator voltage regulator Replace
Corroded or worn battery cable Repair or replace
Loose alternator drive belt
Adjust the belt tension or replace the
belt
Defective wiring harness Repair or replace
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(4) Maintenance
Make sure that the battery cables are firmly connected.
If the terminals are corroded, clean them with a wire brush or sandpapers.
Always disconnect the battery cables with the ignition key removed. When disconnecting the battery
cables with the ignition key turned to ON or ACC position, several electric units can be damaged
due to sudden voltage change.
Check the battery for crack, damage or fluid leaks. Replace it if necessary.
Wipe out the battery fluid on the battery surface using a rubber glove and a clean cloth wetted with
soapy water. -
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If the charge warning lamp ( ) on the instrument cluster comes on while driving, there is a
malfunction in the charge system including the battery. Therefore, carrying out the system check is
needed.
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When there is no engine cranking signal after turning the ignition key ON