ISUZU 4HK-1, 6HK-1 User Manual
Isuzu
4HK-1 and 6HK-1
ENGINE
FUEL SYSTEM
CE APPLICATIONS
Revised 8/29/06 Form Number 5137
1
Table Of Contents
2
Isuzu 4HK-1 and 6HK-1 Engine Overview
The Tier III CX330 Excavators are equipped with an Isuzu 6HK-1 model common rail
fuel system Engine. The Isuzu 4HK-1 model will be used in at least one other
Excavator model. These engines have 4 valves per cylinder, operated by a single
overhead cam to optimize air flow, fuel economy and emissions. The injector is now
located at the center of the piston under the valve cover. The fuel system is now totally
electronically controlled. These engines use an water cooled Exhaust Gas
Recirculation, (EGR) system, which allows a controlled amount of exhaust gas to return
back to the intake. This EGR system is used to reduce the emissions level of the
engine. These engines also use an air to air aftercooling intake air system. The air to
air intake system ports pressurized air flow between the turbocharger and the intake
manifold through an air to air heat exchanger in front of the radiator. The 4HK-1 model
has a displacement of 317 cubic inches (in
model has a displacement of 475 cubic inches (in
The ECM calculates the basic injection amount based on the signals from throttle
position sensor, boost pressure sensor, crank position sensor, cam position sensor, etc.
It regulates the opening/closing period of common rail pressure control valve and the
electric activation of each injector according to the common rail pressure, engine
coolant temperature, etc. at this time, to correct the optimum injection timing and
injection amount.
At engine start (after the key switch is turned to the START position to start the engine,
and until the return of the key switch to the ON position), the fuel injection quantity is
controlled based on information from the start signal, engine speed, and engine coolant
temperature. At low temperature, the fuel injection quantity increases. When the engine
starts completely, this boosted quantity mode at starting is cancelled and normal
running mode is restored.
The ECM calculates the current altitude based on the barometric pressure sensor
signal. It corrects the fuel flow according to the altitude etc. at this time.
The Excavator machine controller communicates with the engine controller (ECM) via
the CAN Data Bus system to control engine speed, return to idle command, activate the
work modes and also to set the engine speed required for the breaker mode.
3
) or 5193 cubic centimeters (cc). The 6HK-1
3
) or 7790- cubic centimeters (cc).
Engine Performance Needs
1. Air
2. Compression
3. Fuel
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Isuzu 4HK-1 and 6HK-1 Engine Overview
The electronic control system for the Isuzu 4HK-1 and 6HK-1 Engines use input
information from a number of sensors and from the Excavator controller to determine
the quantity and timing of the fuel delivery to the engine.
The engine control module (ECM), is located on the inside rear of the cab. The ECM
has two connectors, one an 81 pin and one 40 pin, for inputs and outputs. The engine
control module requires downloading of control software to give it the ability to control all
functions.
Inputs to 40 pin engine harness connector:
• The common rail fuel pressure sensor has 3 wires and is located on the common
rail. This sensor detects the fuel pressure in the common rail, converts the pressure
into a voltage signal, and sends the signal to the ECM. Higher common rail
pressure provides higher fuel pressure sensor voltage while lower pressure provides
lower fuel pressure sensor voltage.
• The 2 wire variable resistor fuel temperature sensor is installed on the fuel supply
pump. The fuel temperature sensor measures the temperature of the drain fuel from
the pump. When the fuel temperature sensor is cold, the sensor resistance is high.
When the fuel temperature increases, the sensor resistance decreases. With high
sensor resistance, the ECM detects a high voltage on the signal circuit. With lower
sensor resistance, the ECM detects a lower voltage on the signal circuit.
Fuel Temp.
(°C)
140 284 75 40 104 1,150
120 248 111 20 68 2,450
100 212 184 0 32 5,740
80 176 318 -20 -4 15,000
60 140 584 -40 -40 45,770
• The 2 wire engine coolant temperature sensor is located on the thermostat housing
at the right front corner of the engine. The coolant sensor's temperature detection
component uses a thermistor. A 5 volt reference voltage is applied at all times to the
sensor from the ECM. The ECM detects a voltage change due to a resistance value
change in the sensor caused by the coolant temperature change.
Coolant
Temp. (°C)
140 284 76 40 104 1,161
120 248 118 20 68 2,500
100 212 190 0 32 5,773
80 176 325 -20 -4 15,216
60 140 591 -40 -40 47,365
Fuel Temp.
(°F)
Coolant
Temp. (°F)
Ohms
Ω
Ohms Ω Coolant
Fuel Temp.
(°C)
Temp. (°C)
Fuel
Temp. (°F)
Coolant
Temp. (°F)
Ohms Ω
Ohms Ω
4
y
Isuzu 6HK1 Common Rail Engine Fuel System
Common
Rail Fuel PSI
Sensor
Crankshaft
Position
Sensor
Pump PSI
Control Valve
(SCV)
Fuel Temp
Sensor
Camshaft
Position
Sensor
Engine Harness 40 Pin
Connector A1
Coolant
Temperature
Sensor
Engine Control Module
Injectors
EGR DC
Motor
Temp. Sensor
Boost PSI
Sensor
EGR Position
Sensor
Main ECM
Power
Rela
Intake Air
Glow
Relay
Boost Temp
Sensor
Engine Harness 81 Pin
Connector A0
Diagnostic
Switch X24
Data Link
Diag Conn X4
Barometric
AMB PSI
Sensor
Memory Clear
Switch X23
ENG Oil
PSI
Sensor
1 Ignition Wire
2 Positive Wires
6 Ground Wires
(Instrumentation
Engine Stop
Switch
Start Signal
(Fuel Boost)
Power Supply
CAN Data Bus
Connector
Throttle,
Idle Up/Down,
Work Modes,
Breaker Mode,
Tach,
& Faults)
5
Isuzu 4HK-1 and 6HK-1 Engine Overview (continued)
Inputs to 40 pin engine harness connector(continued):
• The 2 wire crankshaft position sensor (CKP) is located on the flywheel housing at
the left rear corner of the engine. The CKP sensor detects 45 projections equally
spaced every 7.5° around the flywheel periphery. There is also a space (equal to 3
projections) to act as a top dead center (TDC) reference signal for the engine control
module (ECM). With these 45 pulses and the TDC reference signal, the ECM
calculates the engine speed and exact position of the crankshaft.
• The 2 wire camshaft position sensor (CMP) is located on the cylinder head at the
rear of the camshaft gear. The camshaft position sensor detects a total of the
number of the cylinders in the engine plus an extra one. The extra hole indicates the
top dead center position of number 1 cylinder. Five through holes (four holes
arranged equally every 90° on the gear and one reference hole) on the camshaft
gear flange surface on the 4HK-1 Engine. Seven through holes (six holes arranged
equally every 60° on the gear and one reference hole) on the camshaft gear flange
surface on the 6HK-1 Engine. The camshaft position sensor indicates the rotational
position of the camshaft to the ECM. The CMP signal input, determines the crank
angle and the ECM can use it to control fuel injection and calculate the engine
speed. The crankshaft position sensor (CKP) typically controls these functions,
however it is done by CMP sensor if the CKP sensor is faulty.
Diagnostic aid
If there is relevant Error Code to the crankshaft (CKP) sensor and Camshaft (CMP)
sensor, the engine will not start until memory clear is performed.
If an intermittent trouble is suspected, the following may be the cause:
• Improper connection of harness connector
• Defective harness routing
• Worn harness cover
• Wire disconnection inside harness cover
• The 3 wire boost pressure sensor is located in the piping to the intake manifold of
the engine. The sensor converts the boost pressure into the voltage signal and
sends it to engine control module (ECM). The ECM should detect a higher signal
voltage at a high boost pressure.
• The 4 wire Exhaust Gas Recirculation (EGR) position sensor is installed in EGR
valve and detects the valve lift amount of EGR.
Note:
Do not disassemble the EGR position sensor. If it is faulty, replace it as EGR
valve assembly.
6
y
Isuzu 6HK1 Common Rail Engine Fuel System
Common
Rail Fuel PSI
Sensor
Crankshaft
Position
Sensor
Pump PSI
Control Valve
(SCV)
Fuel Temp
Sensor
Camshaft
Position
Sensor
Engine Harness 40 Pin
Connector A1
Coolant
Temperature
Sensor
Engine Control Module
Injectors
EGR DC
Motor
Temp. Sensor
Boost PSI
Sensor
EGR Position
Sensor
Main ECM
Power
Rela
Intake Air
Glow
Relay
Boost Temp
Sensor
Engine Harness 81 Pin
Connector A0
Diagnostic
Switch X24
Data Link
Diag Conn X4
Barometric
AMB PSI
Sensor
Memory Clear
Switch X23
ENG Oil
PSI
Sensor
1 Ignition Wire
2 Positive Wires
6 Ground Wires
(Instrumentation
Engine Stop
Switch
Start Signal
(Fuel Boost)
Power Supply
CAN Data Bus
Connector
Throttle,
Idle Up/Down,
Work Modes,
Breaker Mode,
Tach,
& Faults)
7
Isuzu 4HK-1 and 6HK-1 Engine Overview (continued)
Inputs to 81 pin engine harness connector:
• The 2 wire intake air temperature (IAT) sensor is installed on intake air tube and
detects the temperature of intake air for optimum fuel injection control.
• The 2 wire boost temperature sensor is installed onto the EGR valve on the
upstream side of intake manifold. The sensor is a thermistor type. The resistance in
the sensor changes as the temperature changes. When the intake temperature
sensor is cold, the sensor resistance is high. When the intake temperature
increases, the sensor resistance decreases. With high sensor resistance, the ECM
detects a high voltage on the signal circuit. With lower sensor resistance, the ECM
detects a lower voltage on the signal circuit.
• The 3 wire barometric pressure sensor is installed on the machine and converts the
ambient barometric pressure into a voltage signal. The ECM calculates barometric
pressure by this voltage signal and corrects the fuel injection amount (high-altitude
correction) as the machine works at a higher elevation.
• The 3 wire engine oil pressure sensor is located on the left side of the engine just
below and forward of the high pressure injection pump.
• An engine emergency stop signal is sent from the machine controller to the engine
controller. The machine controller receives an engine stop signal from the stop
switch located in the instrument cluster.
• As the engine is started (after the key switch is turned to the START position to start
the engine, and until the return of the key switch to the ON position), optimum fuel
injection quantity is delivered based on information from the starter switch signal,
engine speed, and the engine coolant temperature sensor (ECT). At low
temperature, the fuel injection quantity increases. As the engine starts completely,
this boosted quantity mode at starting is cancelled and normal running mode is
restored.
• Power Supply – Ignition power is sent to the engine control module (ECM) any time
that the key switch is in the run position. When the ignition signal is present, the
ECM activates the main relay. Once the Main Relay (K33 on machine schematic) is
activated, battery power is fed to the ECM through the relay normally open (NO)
contact to pins number 2 and 6. When the key switch is turned to the off position,
the ECM continues to hold the main relay activated for a period of time to allow the
ECM to power down safely. This delay is about 10 seconds. The ECM has six
ground connections in total.
8
y
Isuzu 6HK1 Common Rail Engine Fuel System
Common
Rail Fuel PSI
Sensor
Crankshaft
Position
Sensor
Pump PSI
Control Valve
(SCV)
Fuel Temp
Sensor
Camshaft
Position
Sensor
Engine Harness 40 Pin
Connector A1
Coolant
Temperature
Sensor
Engine Control Module
Injectors
EGR DC
Motor
Temp. Sensor
Boost PSI
Sensor
EGR Position
Sensor
Main ECM
Power
Rela
Intake Air
Glow
Relay
Boost Temp
Sensor
Engine Harness 81 Pin
Connector A0
Diagnostic
Switch X24
Data Link
Diag Conn X4
Barometric
AMB PSI
Sensor
Memory Clear
Switch X23
ENG Oil
PSI
Sensor
1 Ignition Wire
2 Positive Wires
6 Ground Wires
(Instrumentation
Engine Stop
Switch
Start Signal
(Fuel Boost)
Power Supply
CAN Data Bus
Connector
Throttle,
Idle Up/Down,
Work Modes,
Breaker Mode,
Tach,
& Faults)
9
Isuzu 4HK-1 and 6HK-1 Engine Overview (continued)
Inputs to 81 pin engine harness connector: (continued)
• The CAN (Controller Area Network) Data Bus Connector transmits communication
between the engine controller and the Excavator controller. This connector
transmits throttle, idle up/down, work mode, breaker mode, tachometer,
instrumentation and fault code information.
• The memory clear (X23), diagnostic switch (X24) and data link (X4) connectors are
not used with the Case Electronic Service Tool (EST) diagnostic system. They are
required when using the Tech 2 Diagnostic Tool.
Outputs from 81 pin engine harness connector:
• When the ignition signal is present from the keyswitch, the ECM activates the main
relay. Once the Main Relay (K33 on machine schematic) is activated, battery power
is fed to the ECM through the relay normally open (NO) contacts to pins number 2
and 6. When the key switch is turned to the off position, the ECM continues to hold
the main relay activated for a period of time to allow the ECM to power down safely.
This delay is about 10 seconds.
• The glow control relay system consists of the ECM, glow relay, glow plug. When the
key switch is turned ON with low engine coolant temperatures, the ECM determines
the glow time and operates the glow relay (K2). After a certain time has elapsed, the
ECM will turn the glow relay to “OFF”. Also, after-glow function allows to stabilize
idling immediately after starting.
Outputs from 40 pin engine harness connector:
• The engine driven high pressure injection pump pressurizes fuel to feed to the
common rail. The injection pump has a suction control valve (SCV), and a fuel
temperature (FT) sensor. The suction control valve (SCV) is installed onto high
pressure pump section and controls supply of fuel (discharge amount) to common
rail. The engine control module (ECM) regulates period of electrical activation time of
the SCV to regulate the fuel discharge amount.
Do not replace the SCV. If it is faulty, replace it as supply pump ASM.
• The exhaust gas recirculation (EGR) system recirculates a part of the exhaust gas to
the engine intake to reduce the combustion temperature inside the cylinders to
reduce NOx (nitrogen oxides) in the exhaust gas. The EGR valve opening is
calculated according to the engine coolant temperature (ECT), the engine speed,
and the target fuel injection quantity. The EGR motor is the brushless DC motor,
and is driven by three phases. The ECM drives the EGR motor through the EGR
motor drive circuits U, V, and W. The motor rotates with a combination of the threephase signals. The ECM sets the Error Code when the EGR motor drive duty is
high and the difference between the target EGR position and actual EGR position is
large.
10
y
Isuzu 6HK1 Common Rail Engine Fuel System
Common
Rail Fuel PSI
Sensor
Crankshaft
Position
Sensor
Pump PSI
Control Valve
(SCV)
Fuel Temp
Sensor
Camshaft
Position
Sensor
Engine Harness 40 Pin
Connector A1
Coolant
Temperature
Sensor
Engine Control Module
Injectors
EGR DC
Motor
Temp. Sensor
Boost PSI
Sensor
EGR Position
Sensor
Main ECM
Power
Rela
Intake Air
Glow
Relay
Boost Temp
Sensor
Engine Harness 81 Pin
Connector A0
Diagnostic
Switch X24
Data Link
Diag Conn X4
Barometric
AMB PSI
Sensor
Memory Clear
Switch X23
ENG Oil
PSI
Sensor
1 Ignition Wire
2 Positive Wires
6 Ground Wires
(Instrumentation
Engine Stop
Switch
Start Signal
(Fuel Boost)
Power Supply
CAN Data Bus
Connector
Throttle,
Idle Up/Down,
Work Modes,
Breaker Mode,
Tach,
& Faults)
11
Isuzu 4HK-1 and 6HK-1 Engine Overview (continued)
Outputs from 40 pin engine harness connector: (continued)
• The injectors are controlled by the engine control module (ECM). The ECM sends a
common power supply to injectors 1, 3 and 5. The ECM also sends a common
power supply to injectors 2, 4 and 6. The ECM fires the injectors by controlling the
ground of the individual injectors. The ECM calculates the basic injection amount
and timing based on the signals from throttle position sensor, boost pressure sensor,
crankshaft (CKP) sensor, camshaft (CMP) sensor, etc. The timing of the injection is
controlled by when the injector activates. The fuel quantity delivered is based upon
the amount of time that the injector is open and also the pressure supplied by the
common rail. To improve combustion in cylinders, the system injects a little fuel (preinjection or pilot injection) and ignites it at the beginning of the cycle. A second
injection (main injection) delivers the fuel required deliver the horsepower needed.
12
y
Isuzu 6HK1 Common Rail Engine Fuel System
Common
Rail Fuel PSI
Sensor
Crankshaft
Position
Sensor
Pump PSI
Control Valve
(SCV)
Fuel Temp
Sensor
Camshaft
Position
Sensor
Engine Harness 40 Pin
Connector A1
Coolant
Temperature
Sensor
Engine Control Module
Injectors
EGR DC
Motor
Temp. Sensor
Boost PSI
Sensor
EGR Position
Sensor
Main ECM
Power
Rela
Intake Air
Glow
Relay
Boost Temp
Sensor
Engine Harness 81 Pin
Connector A0
Diagnostic
Switch X24
Data Link
Diag Conn X4
Barometric
AMB PSI
Sensor
Memory Clear
Switch X23
ENG Oil
PSI
Sensor
1 Ignition Wire
2 Positive Wires
6 Ground Wires
(Instrumentation
Engine Stop
Switch
Start Signal
(Fuel Boost)
Power Supply
CAN Data Bus
Connector
Throttle,
Idle Up/Down,
Work Modes,
Breaker Mode,
Tach,
& Faults)
13
Isuzu 4HK-1 and 6HK-1 Engine Fuel Schematic Overview
Fuel System Hydraulic Function
Fuel comes from the tank and typically will go through a prefilter assembly. From the
prefilter, the fuel then flows to an electric fuel pump, located in the hydraulic pump
compartment. The 24 volt electric fuel pump is powered directly by the battery relay,
through the 65 amp fuse (F23) and the 10 amp electrical fuel pump fuse (F8) in the fuse
box. The electric fuel pump then sends the fuel through the fuel filter also located
hydraulic pump compartment to the inlet port of the high pressure injection pump.
The high pressure injection pump is mounted at the left rear of the engine. This pump
needs to be timed to the engine. To install the pump, bring the engine to TDC and then
align the mark on the pump drive gear to the mark on the front face of the high pressure
pump. Once these conditions are met, install the injection pump. The high pressure
injection pump has a shaft driven gerotor feed (charge) pump which provides fuel to the
pump pressure control valve (Suction Control Valve SCV). The gerotor pump outlet
pressure is controlled by the regulation valve to provide a constant pressure at the inlet
of the high pressure pumping pistons. The high pressurepump PSI regulator (SCV),
located in the injection pump, controls the flow output of the high pressure pump. The
high pressure pump supplies the quantity of fuel to the common rail required to maintain
the pressure dictated by the engine control unit (ECM). This assures that only the
required amount of fuel is pressurized, improving energy efficiency and limiting heating
of fuel in the system. The common rail pressure will range from 3625 to 29,000 PSI (25
to 200 MPa). Excess flow from the feed pump and internal leakage from the injection
pump returns to the tank. The fuel temperature sensor (FT) monitors the temperature of
this fuel.
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