Engine JAC HFC4DA1-2C. Manual — part 24

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

95

closes the fuel drainage hole. The armature is of two-part design. Though the armature block is guided by the pressure
shoulder during the downward movement, it can bounce back following the return spring and thus will not apply
downward force onto the armature and the ball valve.
The close of fuel drainage hole enables the entry of fuel via fuel inlet hole into the control chamber for pressure
establishment. This pressure is equivalent to the rail pressure and applies additional force onto the end face of the
control plunger. The resultant force from this force and spring force overcomes the pressure in the injector nozzle
chamber to close the injector nozzle needle valve.
The close speed of the injector nozzle needle valve depends on the flow passing through the fuel inlet hole. Once the
injector nozzle needle valve hits its lower seat again, the fuel injection stops.

3) Measurement analysis

4) Matching of fuel injector

The matching of fuel injector must be performed in event of any
of the following conditions:

z Replacement of fuel injector.

z Replacement of ECU

z Confusion of installation serial number before and after the

maintenance.

While performing the matching, input the matching code on the
fuel injector (as shown in the figure) in order into the diagnosis
instrument for matching.

2. EGR valve control system

1) Overview

z The electronically controlled EGR valve controls the

open extent of the valve by means of the positive and
reverse rotation of the DC motor and performs the
close-loop control as per the feedback signal of the
position sensor.

z To guarantee the NOx emission of the engine, the ECU

measures and calculates the EGR percentage as per the
input parameters of the engine (such as speed and intake
pressure) and the calibrated MAPs), issues control
signal to the EGR valve, and performs the close-loop
control via the position sensor.

z The EGR valve is installed on the intake manifold. The constant temperature of the EGR valve inlet emission

Fuel injector 1 “high”

Fuel injector 1 "Low”

Fuel injector 4 “high”

Fuel injector 4 "Low”

Fuel injector 2 "Low”

Fuel injector 3 "Low”

Fuel injector 3 “high”

Fuel injector 2 “high”

Cylinder 1

Cylinder 4

Cylinder 3

Cylinder 2

EGR valve

Intake manifold

assembly

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

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can't exceed 260ºC, with the peak temperature no more than 300ºC.

2) Measurement analysis

3. Variable nozzle turbocharger (VNT) control

1) Overview

z HFC4DA1-2C adopts variable section turbocharger technology so that the turbocharger and the engine are well

matched under all working conditions to realize best engine performance.

z The blades of the VNT are connected to the control tie rod and the displacement of the control tie rod is

controlled by the vacuum pressure of the vacuum chamber on the VNT. Changing the vacuum pressure of the
vacuum chamber can change the position of VNT blades and control the flow area of the turbine. The vacuum
pressure of the vacuum chamber is controlled by VNT solenoid valve, of which one port is connected to the
vacuum chamber on the VNT, one port is connected to the vacuum pump, and another port is connected to the air.
This connector in the engine is additionally fitted with filter to prevent the ingress of contaminant (such as dust)
into the valve. The open extent of the VNT solenoid valve is regulated by the PWM wave issued by ECU and the
solenoid valve is installed on the crossbeam of the body water tank.

2) Measurement analysis

4. Fuel metering unit

1) Overview

The fuel metering unit is located on the high pressure fuel pump and is functioned to control the fuel amount from the
low pressure pump to the high pressure pump.

2) Working Principle

The fuel metering valve is installed at the high pressure fuel inlet of high pressure fuel pump and is functioned to
regulate the fuel supply amount and fuel pressure, of which the regulation requirement is subject to the control of
ECU. The control coil of the metering valve is closed when not electrified, which cuts off the fuel supply to the
plunger of high pressure fuel pump. The ECU changes the fuel inlet section area of metering unit by means of pulse
signal to increase or reduce the fuel supply amount.

3) Measurement analysis

Wiring terminals: 1 – Signal terminal; 2 – 12V voltage.

EGR power supply

EGR position signal

EGR signal grounding

EGR control signal terminal

EGR control grounding
terminal

EGR passage section

EGR actuator

Turbocharger actuator

Turbocharger control signal

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

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4) Malfunction Mode

Short-circuit or open-circuit of metering valve; damage of metering valve; contamination of metering valve.

5) Troubleshooting

Use Sunray special diagnosis instrument to check the trouble code and determine the malfunction position. Mainly
check the circuit of metering valve and determine whether there is short-circuit or open-circuit between circuit and the
grounding wire, whether there is short-circuit or open-circuit to power supply, and whether the circuit is consistent
with the given pin definition.

5. Preheating control unit

1) Overview

The preheating control unit is located in the engine compartment and is mainly functioned for the rapid start of engine
under cold state.

2) Working Principle

The preheating control unit is functioned to ensure effective cold start and shorten the warm-up time, which is closely
related to the exhaust emission. The preheating time is a function of coolant temperature. At the start of the engine or
during the actual running, the turn-on duration of the electric heating plug depends on one series of parameters,
including the fuel injection amount and engine speed. The control of the electric heating plug is realized by one power
relay (GCU).

The main part of the electric heating plug is the tubular heating unit. The heating unit is firmly and air-tightly installed
within the electric heating plug housing to guard against corrosion and thermal gas impact. The heating unit is one

Fuel metering unit signal

Fuel metering unit

CP1H and CP4.x metering unit

Fuel amount

Fuel supply to high

pressure pump

Full load fuel amount

Fuel amount characteristic

Idling fuel amount

Ampere

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

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helical metal wire embedded within the magnesium oxide powder (Figure). This helical metal wire is composed of
two resistors in series connection and one heating oil and one control coil are installed on the tip of the heating tube.
The heating coil maintains one resistance almost irrelevant to the temperature and the control coil is made of positive
temperature coefficient (PTC) material. In the new generation heating plug (GSK2), the rise amplitude in the
resistance of control coil is larger than common electric heating plug. With capability of rapidly reaching the
temperature required for ignition (up to 850ºC within 4s) and relatively low constant temperature, new electric heating
plug GSK features outstanding performance. Therefore, the temperature of the electric heating plug is restrained at
one critical value. Therefore, after the start of the engine, the GSKZ electric heating plug can continue to maintain
electrified for 3min. This after-combustion performance improves the noise and exhaust emission of start and
warm-up stages.

The control instrument of the electric heating plug adopts one power relay and the electric switch set to control the
electric heating plug, which control the heating time of electric heating plug and feature the protection and monitoring
functions. Thanks to its diagnosis function, higher grade of electric heating plug control instrument can identify the
malfunction of single electric heating plug and display to the driver. The control input terminal of the electric heating
plug control instrument is connected to the electronic control unit (ECU) via multi-pole plug. To prevent the voltage
drop, the series connection circuit connected to the electric heating plug adopts the threaded pin or connector.

The controlled preheating process and the start process are controlled by the electric heating plug starter switch. The
preheating process is started when the key is turned to “ON” position. When the heating control lamp goes out, the
electric heating plug reaches sufficient temperature and the start process can be conducted. In the subsequent start
process, the fuel drips injected will be atomized and get combusted in the compressed hot air so that the heat released
starts the combustion process.

The after-heating after the successful start can help the warm-up process to form one speed promotion and idle run
with no interruption and little smoke. This can reduce the combustion noise at the cold start. In event of
non-successful start, the protection circuit of the electric heating plug is turned off to prevent the excessive discharge
of the battery.

3) Measurement analysis

4) Malfunction Mode:

Short-circuit or open-circuit of preheating control unit;

Damage of preheating control unit;

5) Troubleshooting:

Use special diagnosis instrument to check the trouble code and determine the malfunction position. Mainly check the
circuit of preheating control unit and determine whether there is short-circuit or open-circuit between circuit and the
grounding wire, whether there is short-circuit or open-circuit to power supply, and whether the circuit is consistent
with the given pin definition.

To preheating

plug

Preheating time feedback

Preheating control unit

Preheating relay

Fuse 5

Power supply