CHAPTER
14
Diesel Engine
Electronics
Instructor Name: (Your Name)
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Learning Objectives
• Discuss the various types of electronically
controlled diesel fuel systems
• Describe why the current flow through an
inductor can not instantly change
• Explain the fundamentals of a closed loop
control system
• Discuss how an in-range failure might not
cause a DTC to be set
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Learning Objectives (continued)
• Explain the difference between in-cylinder
emission reduction and exhaust aftertreatment
• Discuss how a variable geometry turbocharger
can be used to regulate EGR flow rate
• Explain how particulate matter and NOx
exhaust emissions are controlled
• Describe the requirements for HD-OBD and
discuss some of the benefits of this regulation
for technicians
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Electronically Controlled Engine
• Particulate Matter (PM) – Exhaust smoke
• Oxides of Nitrogen (NOx) – One of the
pollutants responsible for smog
• Electronic Control Module (ECM) –
Computer that controls engine fuel system
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Typical 2010 Engine Wiring Harness
Figure 14-1 Typical 2010 engine wiring harness.
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The Basic Tasks of a
Diesel Fuel System
•
•
•
•
Provide injection metering
Atomize the fuel
Provide injection timing control
Control fuel delivery independent of
engine speed and cam shaft geometry
• Perform multiple injection events per cycle
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Bosch RE30 Electronically
Controlled Rack Actuator
Figure 14-5 Bosch RE30 electronically controlled rack actuator.
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Bosch Electronically Controlled
VE Distributive Pump
Figure 14-6 Bosch
electronically controlled VE
distributor injection pump
used on smaller diesel
engines.
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Electronic Unit Injector (EUI)
•
•
•
•
•
NOP – Nozzle opening pressure
NCV – Needle control valve
SV – Spill valve
EUP – Electronic unit pump
Pilot Injection – Small amount of fuel
injected in combustion chamber prior to
main injection
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Single Actuator EUI
Figure 14-10
Single actuator EUI.
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Important Fact
The current flow through an inductor
cannot change instantly from level to
another. However, the voltage measured
across an inductor can instantly change
from one level to another.
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Current Rise
Figure 14-12 Instantaneous current rise in
a resistor circuit.
Figure 14-13 Ramped current rise in
inductor circuit
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Delphi E3 Dual Actuator EUI
Figure 14-15 Delphi E3 dual
actuator EUI.
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Nozzle Can Open
When NCV is Energized
Figure 14-16 Nozzle
opens when NCV is
energized.
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Electronic Unit Pump (EUP)
Figure 14-17
Electronic unit
pump.
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Main Components of a HEUI System
• High pressure oil pump develops the high
pressure engine oil called injection control
pressure (ICP)
• Injection pressure regulator (IPR)
• ICP sensor
• Electronic unit injectors (EUI)
• High pressure oil manifold
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Navistar HEUI Pressure Control
System Components
Figure 14-18 Navistar
HEUI injection
pressure control
system components.
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Closed Loop Circuit
• ECM knows the desired injection control
pressure
• ECM knows the measured or actual
injection control pressure
• Measured injection control pressure can
be changed by increasing or decreasing
the duty cycle of the injection pressure
regulator
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Navistar Single Coil Unit Injector
Figure 14-24 Navistar
single coil HEUI
injector internal
components.
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CAUTION
Follow the OEM’s specific safety
recommendations when troubleshooting
any electronically controlled diesel fuel
system to prevent fatal electric shock.
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Navistar Second Generation
Two-Coil HEUI Injector
Figure 14-25 Navistar
second-generation two-coil
HEUI injector.
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WARNING
Never crack common rail fuel lines open with
the engine running for any reason, including
checking for a misfiring cylinder. Doing so
could cause fuel under extreme pressure to
penetrate your skin resulting in death or
serious injury. Follow OEM instruction for rail
pressure bleed down before loosening any
components in the high-pressure fuel system.
Never install a standard pressure gauge in a
common rail system. The extreme pressure
will cause the gauge to explode.
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Caterpillar Common Rail Fuel System
Figure 14-27 Caterpillar common rail fuel system.
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Common Rail High Pressure Pump
with Control Solenoids
Figure 14-28
Common rail highpressure pump with
control solenoids.
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Solenoid Controlled Common Rail
Injector Nozzle
Figure 14-29 Solenoidcontrolled common rail
injector nozzle.
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Piezo Actuated Common Rail Injector
Figure 14-30 Piezoactuated common
rail injector.
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In Cylinder Exhaust
Emission Reduction
• EGR – Exhaust gas recirculation
• VGT – Variable geometry turbocharger
• Smart Actuator – An actuator that contains
a microprocessor and communication
interface
• Virtual Sensor – Estimated value obtained
from mechanical models of the system
• Learn Cycle – Actuator is driven from
minimum to maximum span at start up
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Typical Cooled EGR System
With VGT Turbocharger
Figure 14-31 Typical cooled EGR system with VGT.
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Electrohydraulic VGT Actuator
Figure 14-32 Electrohydraulic VGT actuator.
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Diesel After Treatment
• Aftertreatment – Modification of exhaust
gasses after they leave the combustion
chamber
• DPF – Diesel particulate filter
• DOC – Diesel oxidization catalyst
• SCR – Selective catalyst reduction
• DEF – Diesel exhaust fluid
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DOC/DPF System
Figure 14-35 DOC/DPF system.
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Bosch Departronic®
Fuel Dosing System
Figure 14-36 Bosch Departronic® fuel dosing system.
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Caterpillar CRS System
Figure 14-37 Caterpillar CRS system. Compressed air is used to
purge the injector and to aid in combustion.
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Caterpillar CRS Injector and
Spark Plug Assembly
Figure 14-38 Caterpillar CRS injector and spark plug
details. Engine coolant is used to cool the injector.
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SCR System Components
Figure 14-39 SCR system components.
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Bosch Denoxtronic® System
Figure 14-40 Bosch Denoxtronic® system.
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Heavy Duty On-Board Diagnostics
•
•
•
•
HD-OBD – Heavy duty on board diagnostics
MIL – Malfunction indicator lamp
Started coming into effect in 2010
Pending DTC – ECM first detects an
emissions related malfunction; MIL will not
illuminate
• Detected DTC – The pending DTC is
detected on second drive cycle; MIL will
illuminate
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Pro Link 9000 EST
Figure 14-42 Pro-Link 9000 scan tool.
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PC Based EST
Figure 14-43 PC-based electronic service tool.
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Injector Cut Out Test Result
Figure 14-44 Injector cutout test results indicate a problem with #2 cylinder.
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Two Channel Oscilloscope
Displays Two Different Signals
Figure 14-46 Two-channel oscilloscope displays two different signals.
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Typical J1939 Voltage Levels
Figure 14-47 Typical J1939 voltage levels using two-channel
oscilloscope referenced to ground.
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Summary
• Vehicles with diesel engines sold in the
U.S. are subject to EPA exhaust emissions
regulations. These regulations have
resulted in substantial decreases of
particulate matter and oxides of nitrogen
emissions. To attain these requirements ,
electronic engine controls were necessary.
• Electronic unit injector (EUI) systems with
single actuators control the spill valve
opening and closing. Dual-actuator EUIs
control both the spill valve and the nozzle
opening.
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Summary (continued)
• Self-inductance prevents the current flow
through an inductor from changing quickly.
• Hydraulically actuated electronic unit injectors
amplify engine lubrication oil under pressure
to generate injection pressures.
• A closed loop control system compares a
desired output to the measured output
referred to as the error. A controller drives the
output such that the error becomes zero,
indicating the desired output and the
measured output are the same. Closed loop
systems are used in a variety of trucks.
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Summary (continued)
• An in-range failure is a condition where the
input voltage at an electronic control module
is within the normal operating voltage range,
but does not correctly represent what is being
measured.
• Exhaust emissions can be controlled by a
combination of in-cylinder techniques and by
exhaust aftertreatment systems.
• A variable geometry turbocharger (VGT) can
be used to regulate EGR flow.
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Summary (continued)
• An H-bridge is an electronic circuit that
causes the polarity of two wires to reverse to
permit directional control of a electric motor.
• Soot is captured in a DPF. A periodic
regeneration of the filter to oxidize the soot is
sometimes necessary. Heat for the
regeneration is produced either by diesel fuel
being injected over a DOC or by igniting the
fuel in a burner in the exhaust.
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Summary (continued)
• SCR uses ammonia to reduce NOx. The
ammonia is produced when an urea water
solution called DEF is injected into the
exhaust stream.
• HD-OBD describes the ability of a diesel
engine to determine that its emissions
have exceeded a threshold and to
illuminate a MIL to alert the driver.
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