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Service TrainingMeeting Guide 672 SESV1672-01
April 1997
TECHNICAL PRESENTATION
3408E/3412E ENGINE CONTROLS
HYDRAULIC ELECTRONIC UNIT INJECTION (HEUI)
PUMPCONTROL
VALVE
OILFILTER
OILCOOLER
HEUI
HEUI
OILSUMP
HYDRAULICPRESSURE
SENSOR
HYDRAULICTEMPERATURE
SENSORCOLD START
OILRESERVOIR OIL PRESSURE
SENSOR
ECM
HYDRAULICSUPPLY
PUMPGROUP
COOL DOWNCIRCUIT
FUEL TANK
FUELTEMPERATURE
SENSOR
PRESSUREREGULATING
VALVE
SECONDARYFUEL
FILTER
FUELTRANSFER
PUMP
PRIMARYFUEL FILTER
WATERSEPARATOR
LUBE OILPUMP
TO LUBESYSTEM
3408E/3412E HEUI FUEL SYSTEM
FLUID MANIFOLDHYDRAULIC PASSAGE
FLUID MANIFOLDHYDRAULIC PASSAGE
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3408E/3412E ENGINE CONTROLSHYDRAULIC ELECTRONIC UNIT INJECTION
(HEUI)MEETING GUIDE 672 SLIDES AND SCRIPT
AUDIENCE
Level II - Service personnel who understand the principles of
engine systems operation, diagnosticequipment, and procedures for
testing and adjusting.
CONTENT
This presentation is designed to prepare a service technician to
identify the components, explain theirfunction, and service the
3408E/3412E Hydraulic Electronic Unit Injection (HEUI) engines in
allcurrent machine and industrial applications.
OBJECTIVES
After learning the information in this presentation, the
serviceman will be able to:
1. locate and identify the major components in the 3400 HEUI
system;
2. explain the functions of the major components in the 3400
HEUI system;
3. trace the flow of oil through the engine hydraulic
system;
4. trace the flow of fuel through the fuel system; and
5. trace the flow of current through the engine electrical
system.
PREREQUISITES
Interactive Video Course "Fundamentals of Mobile Hydraulics"
TEVR9001Interactive Video Course "Fundamentals of Electrical
Systems" TEVR9002Programmed Instruction Course "Basic Electricity"
SEBV0534STMG 546 "Graphic Fluid Power Symbols" SESV1546
Prior training in systems operation and testing and adjusting
procedures for the 3408C/3412C enginesshould be completed before
participating in this training session. Additionally, the
participants shouldhave PC skills and have completed introductory
training in Windows software.
Estimated Time: 8 HoursVisuals: 138 (2 X 2) SlidesServiceman
Handouts: 8 Drawings/Data SheetForm: SESV1672-01Date: 4/97
1997 Caterpillar Inc.
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SUPPLEMENTARY TRAINING MATERIAL
Video Tape "3408E/3412E HEUI Service Introduction"
SEVN3550Brochure "Caterpillar 3408E and 3412E Engines"
LEDH6055ESTMG "Introduction to Electronic Technician"
LEPV5155Brochure "Caterpillar Electronic Technician" NEHP5614Wall
Chart "HEUI Fuel System" (small) LEWH6116Wall Chart "HEUI Fuel
System" (large) LEWH6266Wall Chart "HEUI Engine" LEWH6740
Training Book "Easy Windows, 3.1 Edition" by Shelly
O'HaraAvailable from:Prentice Hall Computer
Publishing0-88022-985-3Attn: Order Dept.201 W. 103rd
St.Indianapolis, IN 46290
Reference Book "Field Guide to Microsoft Windows 95" by Stephen
L. NelsonAvailable from:Microsoft Press International at Fax No.
(206) 936-7329Also available from bookstores
Training Book "Windows 95 for Dummies"Published by IDG BooksIDG
Books World Wide Website: http://www.idgbooks.comAvailable from
bookstores
RECOMMENDED HEUI TOOLING
Caterpillar Electronic Technician Single Use License
JERD2124Caterpillar Electronic Technician Annual Data Subscription
(All Engines and Machines)JERD2129
Communication Adaptor 7X1700PC to Communication Adaptor Cable
7X1425Communication Adaptor to Machine Cable 139-4166(combined ATA
and CDL Data Link cable; replaces 7X1570 and 7X1412)Digital
Multimeter (Fluke 87) 9U7330Cable Probes 7X1710
Hydraulic Unit Injector Puller 131-3921Hydraulic Unit Injector
Sleeve Removal Wrench 111-5051
STMG 672 - 3-4/97
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STMG 672 - 4-4/97
REFERENCES
Troubleshooting Manual "3408E Engine--631E - 637E Wheel
Tractor-Scrapers"SENR1037Troubleshooting Manual "3412E Engine--24H
Motor Grader" SENR1038Troubleshooting Manual "3408E
Engine--834B/836 Wheel Tractors" SENR1052Troubleshooting Manual
"3408E/3412E Engines--D9R/D10R Track-type
Tractors"SENR1054Troubleshooting Manual "3408E/3412E
Engines--988F/990 Wheel Loaders"SENR1060Troubleshooting Manual
"3408E/3412E Engines--769D - 775D Off-highway
Trucks"SENR1062Troubleshooting Manual "3408E/3412E
Engines--Industrial Applications" SENR1065Troubleshooting Manual
"3408E/3412E Engines--651E - 657E Wheel
Tractor-Scrapers"SENR1076
Disassembly and Assembly Manual "3408E/3412E Captive Engines"
SENR1013Disassembly and Assembly Manual "3408E/3412E Industrial and
Marine Engines"SENR1063
Testing and Adjusting Manual "3408E/3412E Engines--Captive
Engines" SENR1018Testing and Adjusting Manual "3408E/3412E
Engines--Industrial Engines"SENR1033
Electrical Schematic "3408E/3412E Captive Engines"
SENR1026Electrical Schematic "3408E/3412E Industrial Engines"
SENR1064
Special Instruction "Using the ECAP" SEHS8742Special Instruction
"Installing the 7X1180 ECAP Expansion Board" SEHS8833
Tool Operating Manual "Using the Communication Adapter"
SEHS9264Tool Operating Manual "Using the Machine Functions Service
Program Module"SEHS9343
Parts Manual "3408E Industrial Engine" SEBP2509
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STMG 672 - 5-4/97
TABLA DE CONTENIDOS
INTRODUCCION..................................................................................................................7Vista
Genreal
..........................................................................................................................8Compoentes
Principales
...........................................................................................................9
SISTEMA DE CONTROL ELECTRONICO ..........
............................................................26Fuel
Injection
.................................................................................................................29Fuel
Injection Control System
.......................................................................................31
FUEL INJECTION SYSTEM
.............................................................................................49System
Components
.......................................................................................................51System
Operation
...........................................................................................................53Hydraulic
Unit Injector Operation
.................................................................................56Injector
Operation
Characteristics..................................................................................61Injector
Components
......................................................................................................64Injector
Removal and Installation
..................................................................................68Injection
Sequence
.........................................................................................................71
HYDRAULIC
SYSTEM......................................................................................................82Hydraulic
Supply Pump Group
......................................................................................83System
Operation
...........................................................................................................93
SYSTEM POWER SUPPLIES
..........................................................................................105ECM
Power Supply
.....................................................................................................106Speed/Timing
Sensor Power Supply
............................................................................108Injector
Power Supplies
..............................................................................................109Analog
Sensor Power Supply
......................................................................................110Digital
Sensor Power Supply
.......................................................................................111Pump
Control Valve Power Supply
.............................................................................112
ELECTRONIC SENSORS AND SYSTEMS
....................................................................114Speed/Timing
Sensors
..................................................................................................115Analog
Sensors and Circuits
........................................................................................117Digital
Sensors and Circuits
.........................................................................................131Engine
Shutdown Systems
...........................................................................................135Demand
Fan Controls
..................................................................................................137Ether
Injection System
.................................................................................................138CAT
Data Link
.............................................................................................................139Logged
Events..............................................................................................................141
MACHINE APPLICATIONS
............................................................................................144D9R/D10R
Track-type Tractors
...................................................................................145988F/990
Series II Wheel Loaders
..............................................................................149769C/771C/773B/775B
Off-highway Trucks
..............................................................1523408E/3412E
HEUI Industrial Engines
.......................................................................155
SLIDE LIST
.......................................................................................................................158
SERVICEMAN'S HANDOUTS
........................................................................................160
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INSTRUCTOR NOTES
STMG 672 - 6-4/97
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STMG 672 - 7-4/97
1
3408E/3412E ENGINE CONTROLS
HYDRAULIC ELECTRONIC UNIT INJECTION(HEUI)
1997 Caterpillar Inc.
INTRODUCTION
This presentation discusses the 3408E/3412E Hydraulic Electronic
UnitInjection (HEUI) Engine Controls in all applications.
The topics are sequenced as follows:
- Introduction and Major Components
- Electronic Control System
- Fuel Injection System
- Hydraulic System
- System Power Supplies
- Electronic Sensors and Systems
- Machine Applications
INSTRUCTOR NOTE: This presentation refers to and
describesElectronic Technician (ET) as the programming tool for
the3408E/3412E engines. As new and more sophisticated
electronicengine controls are now in use, the Electronic Control
AnalyzerProgrammer (ECAP) is no longer adequate for all tasks (such
as flashprogramming). The ET software, installed on a PC, is now
theprinciple tool used in programming.
Major topics
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STMG 672 - 8-4/97
HEUI applications
System features
2
Overview
The 3408E/3412E engines equipped with the HEUI fuel system
areavailable in construction equipment and industrial
applications.
Industrial engines are available in both 3408C/3412C (pump and
line fuelsystem) and 3408E/3412E HEUI versions.
Caterpillar machines powered by the 3408E/3412Eengines which
featureHEUI include:
- 769D/771D/773D Off-highway Trucks
- 988F/990 Series II Wheel Loaders
- D9R/D10R Track-type Tractors
- 631E/637E/651E/657E Wheel Tractor-Scrapers
- 24H Motor Grader
The HEUI engines have many features and benefits not possible
withmechanical fuel systems. These features include a very clean
exhaust,improved fuel consumption and cold starting, simplified
maintenancewith fewer moving parts, and reduced operating
costs.
The system has additional advantages which will be covered later
in thispresentation.
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ST M G 672 - 9 -4/97
3
E lec tronic ally s imilarto E UI s ys tem
Hydraulic pump rais espres s ure
Hydraulic pres s urec ontrolled by E C M
Injec torselec tronic allys ignalled
V A L V UL A DE C ONT R OLDE L A B OMB A
F IL T R O DE
A C E IT E
E NF R IA DORDE A C E IT E
HE UI
HE UI
S UMIDE R ODE A C E IT E
S E NS OR DEP R E S IONHIDR A UL IC A
S E NS OR DET E MP E R A T UR AHIDR A UL IC A
DE P OS IT OP A R A
A R R A NQUE S E NS OR DEP R E S ION DE A C E IT E
E C M
B OMB A DEA C E IT EDE A L T A
P R E S ION
C IR C UIT O DEE NF R IA MIE NT O
T A NQUE DE C OMB US T IB L E
S E NS OR DET E MP E R A T UR AC OMB US T IB L E
V A L V UL AR E G UL A DOR A
DE P R E S ION
F IL T R OS E C UNDA R IODE C OMB US T IB L E
B OMB A DET R A NS F E R E NC IA
C OMB US T IB L E
F IL T R O P R IMA R IODE C OMB US T IB L E
Y S E P A R A DORDE A G UA
B OMB A DEL UB R IC A C ION
A S IS T E MADE L UB R IC A C ION
3408E /3412E H E UI
MUL T IP L E DE A C E IT EA A L T A P R E S ION
MUL T IP L E DE A C E IT EA A L T A P R E S ION
M ajor C omponents
T his schematic shows the various components in the HE UI fuel
system.A detailed explanation of the system and the various
components followslater in this presentation.
T he electronic components in the HE UI fuel system are very
similar tothose used in other E UI systems. However, in the HE UI
system, theinjectors are not actuated by a camshaft.
A high pressure hydraulic pump, which draws oil from the
pressure sideof the lubrication pump, raises the pressure to a
maximum of 22800 kPa(3300 psi). T he pressure is controlled by the
E lectronic Control Module(E CM). T he hydraulic flow is directed
to hydraulic actuators in eachinjector.
T he injectors are electronically signalled (as in the E UI
system) to permitoil under high pressure to move a piston which
then moves the fuelplunger.
SI ST E M A DE C OM B UST I B L E
E N F R IO
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STMG 672 - 10-4/97
Siete t ipos de componentes principales
1. Hydraulic supplypump group
2. ECM
3. Throttle control
4. Speed/timingsensor
5. Injector
6. Temperaturesensor
7. Pressure sensor
CAT Data Link andcoolant flow switch(not shown)
4
2
3
456
7
1
This slide shows seven of the major types of components in the
HEUIfuel system.
Hydraulic Supply Pump Group (1) containing:
- High pressure hydraulic pump
- Pump control valve
- Transfer pump
ECM (2)
Throttle Control (3)
Speed/Timing Sensor (4)
Injector (5)
Temperature Sensor (6)
Pressure Sensor (7)
The CAT Data Link (not shown) provides a two-way communication
pathbetween the HEUI system and the remaining electronic circuits
orsystems on the machine. The CAT Data Link also allows the service
toolto communicate with the engine electronic system.
NOTE: Only one example of each sensor (pressure, temperature
andspeed/timing) is shown on the slide.
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STMG 672 - 11-4/97
3400 HEUI engine topview
1. ECM--the "heart"of the system
Personality moduleaccess panel locatedbelow ECM
2. Hydraulic supplypump group
Wiring harness
5
1
2222
The principal component in the HEUI system, the Electronic
ControlModule (1), is mounted on top of the right front valve
cover.
The ECM is the "heart" of the engine. The ECM performs
enginegoverning, timing and fuel limiting. It also reads sensors
andcommunicates to the instrument display system through the
CATDataLink.
The Personality Moduleis used to program the ECM with all the
ratinginformation for a particular application. The Personality
Module can bechanged by direct replacement or can be flash
programmed(reprogrammed) using a PC. The Personality Module Access
Panel islocated below the ECM.
The Hydraulic Supply Pump Group(2) is mounted in the vee of
theengine in the same position as the original fuel pump and
governor for the3408C/3412C engines. Flow from this pump supplies
the actuatingpressure for the injectors. Mounted on the rear of the
pump is the fueltransfer pump.
Among the visible components are the Wiring Harnessand 40
PinConnectorsto the ECM.
INSTRUCTOR NOTE: The slides which follow show machine
andindustrial engines. The physical appearance and function of
theHEUI machine and industrial engine components are very
similar.
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STMG 672 - 12-4/97
Engine upper left sideview
1. Fuel temperaturesensor
2. Atmosphericpressure sensor
3. Lubrication oilpressure sensor
4. Hydraulictemperature sensor
5. Machine interfaceconnector
6. Ground bolt
6
12 4
53
6
This view from the upper left side of the engine shows the
FuelTemperature Sensor (1). The Atmospheric Pressure Sensor (2)
ismounted on the Hydraulic Supply Pump Group mounting adapter.
Mounted on the Hydraulic Supply Pump Group is the Lubrication
OilPressure Sensor (3). The sensor is used by the ECM to generate a
lowoil pressure warning for the operator.
Also mounted on the Hydraulic Supply Pump Group is
thelUBRICATIONTemperature Sensor (4). This sensor is used by the
ECM for viscositycompensation to maintain consistent fuel delivery
and injector timingregardless of viscosity changes caused by
varying hydraulic temperatures.Both sensors are threaded into the
supply pump case.
The 40 Pin Machine Interface Connector (5) is mounted behind
theHydraulic Supply Pump Group. This component makes the
connectionbetween the engine and machine wiring harnesses.
A vital part of the wiring assembly is the Ground Bolt (6)
mounted onthe machine interface connector bracket.
NOTE: Oil flow from the Hydraulic Supply Pump Group will
bereferred to as "hydraulic" to avoid confusion with the
lubricationsystem.
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STMG 672 - 13-4/97
1. Timing calibrationconnector
2. Hydraulic pressuresensor
3. Injector connector
7
2
13
The Timing Calibration Connector(1) is located adjacent to the
ECM.
The Hydraulic (Injection Actuation) Pressure Sensor(2) is
locatedbetween the valve cover bases in the right Fluid Supply
Manifold.
The Injector Connector(3) is one of four connectors on a 3408E.
(Each connector supplies current to two injector solenoids.)
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STMG 672 - 14-4/97
Coolant temperaturesensor (arrow)
8
The engine Coolant Temperature Sensor(arrow) is located in the
frontof the right cylinder head. This sensor is used with the ECM
to controlvarious functions. The following systems or circuits use
the TemperatureSensor output to the ECM:
The Vital Information Management System (VIMS) or
CaterpillarMonitoring System Coolant Temperature Gauge over the
CATDataLink.
The High Coolant Temperature Warning Alert Indicator LED
andGauge on the VIMS or Caterpillar Monitoring System panel.
(Theinformation is transmitted over the CATData Link.)
The Engine Demand Fan Control, if installed, uses the sensor
signalreference to provide the appropriate fan speed.
The Cat Electronic Technician (ET) status screen coolant
temperatureindication.
The Coolant Flow Switch(not visible in this view) is mounted
below thecoolant temperature sensor at the inlet to the oil
cooler.
Coolant flow switch(not visible)
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STMG 672 - 15-4/97
Secondaryspeed/timing sensor(arrow)
9
This view shows one of the Speed/Timing Sensors(arrow). A sensor
ismounted on each side of the timing gear housing. This slide shows
thesecondary Speed/Timing Sensor. The primary Speed/Timing Sensor
islocated closest to the ECM.
These sensors are used to calculate engine speed and crankshaft
positionfor timing purposes.
The sensors are self-adjusting, but special precautions are
necessaryduring installation to prevent damage. (The precautions
are describedlater in the presentation.)
NOTE: The sensors maintain a zero clearance with the timing
wheel.
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STMG 672 - 16-4/97
Rueda de Sincronizacion
Marca de sincronizacion
10
Esta es la rueda de sincronizacion, fuera del motor
Notice the wide 50/50 size slot and equal size tooth (arrow) cut
in thewheel. Las otras 23 ranuras son de tamao 80/20
La ranura y diente 50/50 es usada po elECM como punto de
referencia paradeterminar la posocion del motor para la
sincronizacion del combustible (se explica completamente mas
adelante). El sensor de Speed/Timing puedeidentificar este diente
porque crea una seal diferente que los otros dientes
Una marca de sincronizacion "H," al reverso de larueda de
sincronizacion es usada parasincronizar la rueda en relacion a los
otros engran. de sincroniz. y el TDC del cigueal.
Ranura y diente 50/50(fecha)
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STMG 672 - 17-4/97
Turbo inlet pressuresensor (arrow)
11
The Turbo Inlet Pressure Sensor(arrow) is mounted between the
airfilter and the turbocharger. Not all machines have this sensor
installed.
This sensor (if installed) is used in conjunction with the
atmosphericpressure sensor to measure air filter restriction for
engine protectionpurposes. The difference between the two pressure
measurements is usedas the filter differential pressure.
The engine ECM uses this calculation to determine whether
derating isnecessary to protect the engine.
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STMG 672 - 18-4/97
Turbo outlet pressuresensor (arrow)
12
At the front of the engine in the right cylinder head is the
Turbo Outlet(Boost) Pressure Sensor (arrow). This sensor is used
with the ECM tocontrol the air/fuel ratio electronically. This
feature allows very precisesmoke control, which was not possible
with mechanically governedengines.
The sensor also allows boost pressure to be read using the
service tools.
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STMG 672 - 19-4/97
Identify components:
1. Atmosphericpressure sensor
2. Fuel temperaturesensor
3. Primaryspeed/timingsensor
4. Secondaryspeed/timingsensor
13
1
2
43
The Atmospheric Pressure Sensor(1) is installed on the
HydraulicSupply Pump Group adapter and is vented to the atmosphere.
This sensorhas various functions which are fully described later in
the presentation.A foam block below the sensor helps prevent the
entry of dirt into thesensor.
Briefly, the sensor performs the following functions:
- Ambient pressure measurementfor automatic altitudecompensation
and automatic air filter compensation.
- Absolute pressure measurementfor the fuel ratio control,
ET,Caterpillar Monitoring System panel (gauge)
pressurecalculations.
The Fuel Temperature Sensor(2) is used for automatic fuel
temperaturecompensation.
The Primary(3) and Secondary (4) Speed/Timing
Sensors(discussedearlier) are located on the rear of the timing
gear housing.
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STMG 672 - 20-4/97
1. Aceite de suministro
2. Valvula Compensadora
3. Valvula de control bomba
4. Bomba trasnferencia
14
4
3
2
1
A number of components are mounted on the Hydraulic Supply
PumpGroup. The Oil Supply Line(1) from the oil gallery is a large
diameterline for maximum delivery during cold operation. The
hydraulic pumpdepends on the lubrication pump for the first stage
of pressure increase.
The Compensation Valve(2) is mounted at the rear of the pump.
Belowthe compensation valve is the Pump Control Valve(3). This
valve mayalso be referred to as the "injection actuation pressure
control valve."This valve controls the angle of the swashplate,
which varies the output ofthe pump.
The Fuel Transfer Pump(4) is mounted at the rear of the
HydraulicSupply Pump and is driven by the main drive shaft which
extends throughthe supply pump.
Also visible in this slide are the transfer pump inlet and
outlet fuel linesand the pressure and temperature sensors
(discussed earlier).
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STMG 672 - 21-4/97
Lubrication oil pump
Supplies oil tolubrication andhydraulic injectionactuation
systems
15
Mounted internally in the oil pan is the Bomba de aceite de
lubricacion. Thispump supplies oil at approximately 400 kPa (65
psi) to the oil gallery forengine lubrication.
Oil is also supplied to the hydraulic pump for injection
actuationpurposes. For this reason, the HEUI engine lubrication oil
pump is largerthan the pump in the previous engine to accommodate
the increased needsof the lubrication and the hydraulic injection
actuation systems.
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STMG 672 - 22-4/97
Timing calibrationsensor (arrow)
16
The Timing Calibration Sensor(arrow) is installed when required
in theflywheel housing.
This sensor (magnetic pickup) is installed in the hole normally
reservedfor the timing pin. (The pin is used to position the
crankshaft with theNo. 1 piston at top dead center.)
NOTE: On some applications (i.e. some track-type tractors)
whereaccessibility is limited, this sensor is permanently
installed.
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STMG 672 - 23-4/97
1. Water separatorand primary filter
2. Two micronsecondary filter
Water separatorservice intervals
17
1
2
The Water Separator (1), which also functions as a Primary Fuel
Filter,is an important part of the fuel system.
As with any high pressure fuel system with operating pressures
atapproximately 150000 kPa (22000 psi), fuel quality is important.
Waterin the fuel can cause corrosion of the plungers and barrels.
Dirt can causeearly hour wear on the same components. The water
separator contains a30 micron filter. The Priming Pump is mounted
on the filter base.
For the same reason, the correct two micron Secondary Filter (2)
mustbe used in the system. The clearance between the plunger and
barrel isapproximately 5 microns. Typically, the 3 to 8 micron
abrasive materialprematurely wears out the fuel system
components.
The Water Separator is serviced daily by draining the water. The
WaterSeparator filter is serviced with a new element every 500
hours.
INSTRUCTOR NOTE: The high fuel pressures mentioned in thistext
are mandated by the need to meet environmental regulations forsmoke
and emissions. Also, to maintain good fuel consumption,
highpressures are required. The HEUI system meets and surpasses
thoserequirements.
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ST M G 672 - 24 -4/97
18
E ngine c omponentidentific ation
A DE M IIMODUL O DE
C ONT R OLE L E C T R ONIC O
(E C M) P E R NO DET IE R R A
DIS Y UNT OR15 A
R E L E P R INC IP A LDE P OT E NC IA
INT E R R UPDE L L A V E
S E NS OR DE P R E S ION DE S A L IDA
S E NS OR P R IMA R IO DEV E L OC IDA D/S INC R ONIZA C ION
S E NS OR DE P R E S ION DEA C T IV A C ION DE INY E C C ION
24 V
C ONE C T OR DEINT E R F A Z DEL A MA QUINA
MA ZO DE C A B L E SDE L MOT OR
V A L V UL A DE C ONT R OL DE P R E S ION
S E NS OR DE T E MP E R A T UR A
S E NS OR DE P R E S ION A T MOS F E R IC A
S E NS OR DE P R E S ION DE
S E NS OR DE T E MP E R A T UR A DE
S E NS OR DE T E MP E R A T UR A
INT E R R UP T OR DE F L UJ O
8 O 12INY E C T OR E S
A C C E S O A L AS ONDA DE S E R V IC IO
T A B L E R O DEINS T R UME NT OS
C ONT R OL DE L R E T A R DA DOR A UT OMA T IC O
C ONT R OL DE L A T R A NS MIS ION E P T C II
HE R R A MIE NT A E L E C T R ONIC A DE S E R V IC IO
E NL A C E DE DA T OS C A T
V E NT IL A DOR
S E NS OR DE V E L OC IDA D
V A L V UL A P R OP OR C IONA L DE C ONT R OL
T UR B O INL E T P R E S S UR E S E NS OR
INT E R R UP T OR E S DE R E S E R V A DE L A C E L E R A DOR ,
DE A C T IV A C ION DE
B A J A E N V A C IO E L E V A DA Y DE A P A G A DO DE S DE E L
S UE L O
S E NS OR DE LA C E L E R A DOR P E DA L DE L
A C E L E R A DOR
INT E R R UP T OR G E NE R A L
S IS T E MA 3408E /3412E HE UIDIA G R A MA DE C OMP ONE NT E
S
C A B L E S DEL A MA QUINA
T his schematic identifies the external HE UI engine components
(shownon the engine harness side of this schematic). T he
components shown onthe left side of the diagram are mounted on the
engine and those on theright are machine mounted. Notice that the
turbo inlet pressure sensor ismounted on the machine.
I NST R UC T OR NOT E : A t this time, it is r ecommended that
eachcomponent be located on the machine and the function of eachr
eviewed with the students. A list of the components follows on
thenext page.
Some additional (used/defective) components available
forexamination on a table will be helpful. A n E C M with the Per
sonalityM odule and var ious sensor s can be examined at this time
and usedfor tr oubleshooting exer cises later .
DE L V E NT IL A DOR
DE L V E NT IL A DOR
MA ZO DE
DE A C T IV A C ION DE L A INY E C C ION
S E NS OR DE R E S E R V A DEV E L OC IDA D/S INC R ONIZA C
ION
DE L R E F R IG E R A NT E
DE L T UR B OC OMP R E S OR
A C E IT E DE L MOT OR
A C E IT E DE L MOT OR
DE L C OMB US T IB L E
DE R E F R IG E R A NT E
DE C E NT R OS UP E R IOR (T DC )
-
STMG 672 - 25-4/97
Electrical Components
Conector del ECM 40 Pins
Modulo de Personalidad
Timing Calibration Connector and Installation Location
Sensor de presion hhidraulica
Sensor de Temperatura Hidraulica
Primary Speed Timing Sensor
Secondary Speed Timing Sensor
Sensor de Temperatura de Refrigerante
Sensor de Presion Atmosferica
Sensor de presion de entrada del turbo
Sensor de presion de salida del turbo
Sensor de presion de aceite
Sensor de Temperatura de combustible
Switch de flujo de refrigerante
Conector de interfase a la maquina
Pernos de tierra de motor y de maquina
Conector al Data Link
Sensor de posicion de acelerador
Switches de apagado
Componentes Mecanicos
Grupo de bomba de suministro de aceite
Valvula de control de la bomba
Valvula de Compensacion
Reservorio para arranque en frio
Valvulas check
Manifold de fluido
Filtro Primario / Separador de agua
Filtro secundario
Bomba de transferencia
Valvula Reguladora de presion
Inyector
Tubo Jumper
Adaptador de aceite para inyector
-
STMG 672 - 26-4/97
19
SISTEMA DE CONTROL DE ELECTRONICO
ELECTRONIC CONTROL SYSTEM
This section of the presentation explains the Electronic Control
Systemincluding the following components:
ECM
Personality Module
Hydraulic Electronic Unit Injector Solenoids
Timing Wheel
Also covered are the following subsystems and related
procedures:
Timing control
Fuel quantity control
Speed control
Cold modes
Timing calibration
-
STMG 672 - 27-4/97
ECM:
- Governor
- Fuel systemcomputer
- Injection pressurecontroller
- Injection timingcontroller
Same ECM used in allapplications
20
The Electronic Control Module (ECM) functions as the governor
and fuelsystem computer. The ECM receives all the signals from the
sensors andenergizes the injector solenoids to control timing and
engine speed.
The ECM is sealed except for access to the software which is
contained inthe Personality Module (next slide). This ECM is the
second generationof Advanced Diesel Engine Management Systems and
may be frequentlyreferred to as "ADEM II."
This ECM is used in all applications of the 3408E and 3412E
engines.The ECM can also be moved from one application to another;
however, apassword is required to activate the ECM when new
software is installed.
NOTE: The ECM has an excellent record of reliability.
Therefore,any problems in the system are most likely to be in the
connectorsand wiring harness. In other words, the ECM should
typically be thelast item in troubleshooting.
-
STMG 672 - 28-4/97
Personality modulecontains software
Two methods toupgrade software
ECM is sealed exceptfor personality module
21
The Personality Module (shown removed from the ECM) contains
thesoftware with all the fuel setting information (such as
horsepower, torquerise and air/fuel ratio rates) which determines
how the engine willperform. The Personality Module is installed on
the lower face of theECM, behind the access panel.
At this time, two methods can be used to update the
software:
1. Flash Programming: Electronic reprogramming of the
PersonalityModule software. (This method is preferred when updating
thesoftware.)
2. Remove and replace the Personality Module. (This method maybe
used if Flash Programming is not possible.)
Upgrading the software is not a routine task, but might be
performed forreasons of a product update, a performance improvement
or a productproblem repair.
NOTE: The ECM is sealed and needs no routine adjustment
ormaintenance. The Personality Module is mounted within the
ECM.Installation of the Personality Module is the only reason to
enter theECM. This operation would normally be performed during an
ECMinstallation or a software update.
-
STMG 672 - 29-4/97
Unit injectors
Electrically signalled,hydraulically actuated
22
Fuel Injection
The 3400 HEUI unit injector is electrically similar to the 3500
electronicunit injector. The injector is controlled electrically by
the ECM but isactuated hydraulically. The signal from the ECM
controls the openingand closing of the solenoid valve. The solenoid
valve controls the flow ofhigh pressure hydraulic oil to the
injector. This system enables the ECMto control fuel volume, timing
and injection actuation pressure (hydraulicsupply pump
pressure).
The injector solenoids operate on 105 Volts direct current.
Alwaysremain clear of the injector area when the engine is running
orelectric shock may occur.
-
STMG 672 - 30-4/97
Injector testing
23
PRUEBA DE SOLENOIDES DE INYECTOR
CORTE DE CILINDROS
PRUEBA AUTOMATICA DE INYECTORES
METODOS DE PRUEBAS EN INYECTORES HEUI
Three tests can be used to determine which cylinder or injector
ismalfunctioning:
INJECTOR SOLENOID TESTThis test is performed while the engine is
stopped. The injector solenoidscan be tested automatically with the
service tool using the InjectorSolenoid Test. This function
individually tests each solenoid in sequenceand indicates if a
short or an open circuit is present.
CYLINDER CUT-OUT (Manual test)This test is performed while the
engine is running at any speed. The 105 Volt pulse can be
individually cut out to aid in troubleshootingmisfire problems in
the injector and the cylinder.
AUTOMATIC INJECTOR TESTThis test is performed with the service
tool while the engine is running atany speed. The test makes a
comparative evaluation of all injectors andnumerically shows the
results. The test enables an on-engine evaluationof the injectors.
(This test cannot be performed using the ECAP.)
A satisfactory test of all injector solenoids without any
diagnosticmessages indicates that a mechanical problem in the
cylinder probablyexists.
-
ST M G 672 - 31 -4/97
24
F uel timing c ontrol
Inputs to timingc ontrol
B enefits of a " s mart"timing c ontrol
L OG IC A DE C ONT R OL DE HE UI
V E L OC IDA D DE L
C A NT IDA D DE F UE LR P M
MODO F R IO
S E L E C TT IMING
C ONV E R TDE S IR E D
T IMINGT E MP E R A T U
C ONT R OL DE L A S INC R ONIZA C ION
DE G R E E S B T DC DE S IR E DT IMINGB T DC
T IMING
F UE L INJ E C T IONT IMING WA V E F OR M
F uel I njection C ontr ol System
T his diagram shows the timing control logic within the E
CM.
E ngine speed, fuel quantity (which relates to load), and
hydraulic oiltemperature input signals are received by the timing
control. T hehydraulic temperature signal determines when the Cold
Mode should beactivated. T hese combined input signals determine
the start of fuelinjection.
T he timing control provides the optimum timing for all
conditions. T hebenefits of a "smart" timing control are:
- R educed particulates and lower emissions
- Improved fuel consumption while still maintaining
performance
- E xtended engine life
- Improved cold starting
MOT OR
C OMB US T IB L E
-
STMG 672 - 32-4/97
25
Fuel quantity control
Inputs to fuel quantitycontrol
Start of injectiondetermines timing
Injection duration andinjection actuationpressure determinefuel
quantity
ELECTRONICGOVERNOR
TORQUEMAPS
FRCMAPS
TURBO OUTLET ANDATMOSPHERIC
PRESSURE SENSORS
ENGINECONTROL
LOGIC
THROTTLE
SHUTDOWNS
INJECTIONACTUATIONCONTROL
ENGINE RPM
TDC
87654321
FUELINJECTIONCONTROL
TO PUMPCONTROL VALVE
SIGNALSTO FUEL
INJECTORS
SPEED/TIMINGSIGNAL
ENGINE RPM
SPEED/TIMINGSENSORS
TIMINGWHEEL
ENGINE RPM
ECM
3408E/3412E ELECTRONIC GOVERNOR
HYDRAULIC OILTEMPERATURE ANDPRESSURE SENSORS
Four inputs control fuel quantity:
1. Engine speed
2. Injection actuation (hydraulic) pressure
3. Throttle position
4. Boost
These signals are received by the electronic governor portion of
the ECM. The governor then sends the desired fuel signal to the
fuel injection andinjection actuation controls. The fuel quantity
control logic also receivessignals from the fuel ratio and torque
controls.
Three variables determine fuel quantity and timing:
- The start of injection determines engine timing.
- The injection duration and injection actuation
(hydraulic)pressure determine the quantity of fuel to be
injected.
-
STMG 672 - 33-4/97
26
Speed/timing sensors
Three functions of thespeed/timing sensor
Sensor installation
ADEM IIELECTRONIC
CONTROLMODULE
(ECM) GROUNDBOLT
15 AMPBREAKER
MAINPOWER RELAY
KEYSWITCH
TURBO OUTLET PRESS. SENSOR
SECONDARYSPEED/TIMING SENSOR
PRIMARYSPEED/TIMING SENSOR
HYDRAULICPRESSURE SENSOR
24 V
MACHINEINTERFACE
CONNECTOR
ENGINEHARNESS
PUMP CONTROL VALVE
COOLANT TEMP. SENSOR
ATMOSPHERIC PRESS. SENSOR
OIL PRESSURE SENSOR
HYDRAULIC TEMP. SENSOR
FUEL TEMPERATURE SENSOR
COOLANT FLOW SWITCH
8 OR 12INJECTORS
TDC SERVICEPROBE ACCESS
INSTRUMENTPANEL
AUTO RETARDER CONTROL
EPTC II TRANSMISSION CONTROL
ELECTRONIC SERVICE TOOL
CAT DATA LINK
FANFAN SPEED SENSOR
PROPORTIONAL VALVE
TURBO INLET PRESSURE SENSOR
THROTTLE BACK-UP, ELEVATED LOW IDLE ENABLE,AND GROUND LEVEL
SHUTDOWN (2) SWITCHES
THROTTLESENSOR
ACCELERATORPEDAL
DISCONNECT SWITCH
HEUI SYSTEMCOMPONENT DIAGRAM
MACHINEHARNESS
Two Speed/Timing Sensors are installed: a primary and a
secondary. TheSpeed/Timing Sensors serve three functions in the
system:
1. Engine speed measurement
2. Engine timing measurement
3. Cylinder and TDC location
The Speed/Timing Sensors, which are mounted on the front
housingbelow the timing gear wheel, are self-adjusting during
installation andhave zero clearance with the timing wheel.
The head is extended prior to installation. The action of
screwing in thesensor pushes the head back into the body until the
head contacts thetiming wheel. This contact is only momentary while
the engine isstarting. After start-up, the head runs with zero
clearance.
-
STMG 672 - 34-4/97
27
Primary sensor
Secondary sensor
Power supply
393229381812
732-PK996-GN998-BR999-WHF723-PKF724-PU
SECONDARY ENGINE SPEED+V TIMINGDIGITAL RETURNPRIMARY ENGINE
SPEEDTIMING CAL +TIMING CAL -
ECM(3408E/3412 E)
P2 J2
ABC
ORBKWH
SECONDARYSPEED/TIMING
SENSOR
ABC
ORBKWH
PRIMARYSPEED/TIMING
SENSOR
TIMING CALIBRATIONCONNECTOR
12
SPEED/TIMING SENSORS
P44 J44
P20 J20
P26 P1 J1
The Primary Speed/Timing Sensor (right side of engine) measures
enginespeed for governing, and crankshaft position for timing
purposes andcylinder identification.
The Secondary Speed/Timing Sensor (left side of engine)
allowscontinuous operation if the primary sensor fails. A failure
of the primarysensor will cause the ECM to automatically switch to
the secondarysensor. Also, the check engine lamp will come on.
The ECM supplies 12.5 1 Volts to the Primary and
SecondarySpeed/Timing Sensors.
Connectors A and B transmit the common power supply to the
sensors.The C connectors transmit separate signals from each sensor
to the ECMfor back-up purposes.
NOTE: The Speed/Timing Sensors have a dedicated power supply.No
other circuits should be spliced into this power supply.
-
STMG 672 - 35-4/97
Timing wheel
28
The Timing Wheel is an integral part of the drive gear for the
pump.Timing marks are used to locate the wheel in the correct
position relativeto the crankshaft. This Timing Wheel is common to
all 3408E/3412Eengines.
As previously stated, the Timing Wheel has a total of 24 teeth.
23 teethare large with small spaces between them (80/20 relative
size).
The other tooth and space have equal dimensions (50/50 relative
size).This configuration is used by the ECM to locate TDC on the
No. 1cylinder.
NOTICE
The head of the sensor MUST NOT be positioned in the timing
wheel(wide) slot during installation. Incorrect positioning will
causedamage to the sensor head.
-
STMG 672 - 36-4/97
29
Sensors generate aPWM signal fromtiming wheel teeth
Failure modes
4
3
6
5
7
2
1
8
REF
REF
REF
REF
REF
REF
REF
REF
TDC
TDC
TDC
TDCTDC
TDC
TDC
SINGLE50/50 TOOTH
TIMING WHEELROTATION
TDC CYLINDER No. 1
TIMINGCALIBRATIONRANGE 10
PRIMARYSPEED/TIMING
SENSOR
SECONDARYSPEED/TIMING
SENSOR
TIMING WHEEL
The Speed/Timing Sensors are positioned vertically over the
teeth.
The teeth and sensors generate a Pulse Width Modulated (PWM)
outputsignal for the purpose of timing and a frequency modulated
output signalfor speed measurement.
The Secondary Speed/Timing Sensor functions the same as the
primarysensor. The Secondary Speed/Timing Sensor is used when the
signal fromthe primary sensor is lost or distorted. If the
secondary sensor is selected,it will continue in use until the
engine is shut down and cranked. Then,the primary sensor will be
selected.
Unless the engine is cranking, the ECM will not switch from
thesecondary to the primary sensor. This feature prevents constant
switchingbetween sensors if an intermittent fault occurs.
INSTRUCTOR NOTE: A description of PWM signals is providedlater
in this presentation (Sensors and Systems).
-
STMG 672 - 37-4/97
30
Cranking
Timing wheel teethand spacing
A B C D E F G
TIMING WHEEL ROTATION
H
80/20 % 80/20 % 80/20 %80/20 % 50/50%80/20 % 80/20 %
TIMING GEAR TOOTH TABLE
TABLEENTRY
CYLINDERREFERENCE
ABCDEFGH
80 %80 %80 %80 %80 %80 %80 %50 %
CRANKING
NONE IDENTIFIED
PWM DUTYCYCLE
The Speed/Timing Sensor uses the timing wheel with the teeth
arrangedas shown to determine:
- Top Dead Center No. 1 (When found, the cylinders can
beidentified.)
- Engine speed
The sequence of signals shown in the second column (duty cycle)
isanalyzed by the ECM. At this point, no fuel will be injected
until certainconditions have been met.
Unlike EUI engines, this engine does not rely on tooth
configuration toprevent reverse rotation. The lubrication and the
hydraulic pumps will notdevelop pressure during reverse rotation,
and will not move the injectorsto pump fuel. Therefore, the engine
cannot run in reverse.
-
STMG 672 - 38-4/97
31
After patternrecognition
Initial firing sequence
TIMING WHEEL ROTATION
CYL NO. 3REFERENCE
EDGE
CYL NO. 4TDC
CYL NO. 4REFERENCE
EDGE
CYL NO. 8REFERENCE
EDGE
CYL NO. 3TDC
TIMING GEAR TOOTH TABLE
CYLINDERREFERENCE
80 %80 %80 %80 %80 %80 %80 %50 %
AFTER PATTERN RECOGNITION
NOCYL NO. 3NONOCYL NO. 4NONOCYL NO. 8
TABLEENTRY
ABCDEFGH
PWM DUTYCYCLE
A B C D E F G H
During start-up, the sensor initially monitors the pulses
created by thepassing teeth and identifies the sequence as shown.
After a completerotation, the control can recognize the location of
TDC from the pattern inthe above illustration.
During initial cranking, no fuel is injected until:
The timing wheel has completed a full revolution.
TDC for all cylinders is identified by the control.
After the sensor has provided the necessary signals, the ECM is
ready tostart injection (if sufficient hydraulic pressure is
available to the injectors).
NOTE: The reference points in the illustration are positions on
thetiming wheel from which the control measures the point of
injectionand TDC.
-
STMG 672 - 39-4/97
32
Normal operation
Signal patternidentifies TDC
Conditions forinjection
TIMING GEAR TOOTH TABLE
PWM DUTYCYCLE
CYLINDERREFERENCE
80 %80 %80 %80 %80 %80 %80 %50 %
NORMAL OPERATIONNOCYL NO. 3NONOCYL NO. 4NONOCYL NO. 8
CYL NO. 4(REFERENCE)
CYL NO. 4ACTUAL TDC
(CALIBRATED)
62 BTDC (EEPROM)
DES TIMING
NO. 4INJECTION
TABLEENTRY
TIMING WHEEL ROTATION
ABCDEFGH
A B C D E F G H
CYL NO. 3(REFERENCE)
CYL NO. 3ACTUAL TDC
(CALIBRATED)
62 BTDC (EEPROM)
DES TIMING
DELAY NO. 3INJECTION
DELAY
ASSUMEDTDC
ASSUMEDTDC
During normal operation, the ECM can determine timing from
thesequence reference point for each cylinder. The reference point
is storedby the ECM after calibration is performed.
Injection timing is calibrated by connecting a TDC probe to the
serviceaccess connector on the engine harness, and by activating
the calibrationsequence with the Caterpillar ET service tool. The
ECM raises the enginespeed to 800 rpm (to optimize measurement
accuracy), compares theactual No. 1 TDC location to the assumed
cylinder No. 1 TDC location,and saves the offset in the EEPROM
(Electrically Erasable ProgrammableRead Only Memory).
NOTE: The calibration offset range is limited to 10
crankshaftdegrees. If the range is exceeded, the offset is set to
zero (nocalibration) and a calibration diagnostic message is
generated.
-
STMG 672 - 40-4/97
33
Timing calibrationsensor
393229381812
732-PK996-GN998-BR999-WHF723-PKF724-PU
SECONDARY ENGINE SPEED+V TIMINGDIGITAL RETURNPRIMARY ENGINE
SPEEDTIMING CAL +TIMING CAL -
ECM(3408E/3412E)
P2 J2
ABC
ORBKWH
SECONDARYSPEED/TIMING
SENSOR
ABC
ORBKWH
PRIMARYSPEED/TIMING
SENSOR
TIMING CALIBRATIONCONNECTOR
P26
TIMING CALIBRATIONSENSOR
TIMING CALIBRATION SENSOR
P44 J44
P20 J20
P1 J1
12
The Timing Calibration Sensor(magnetic pickup) is installed in
theflywheel housing during calibration. The connector is located
above theECM. (On some machines, i.e. D9R/D10R, the sensor is
permanentlyinstalled.)
Using the Caterpillar ET service tool, timing calibration is
performedautomatically for both sensors when selected on the
appropriate screen.
The desired engine speed is set to 800 rpm. This step is
performed toavoid instability and ensures that no backlash is
present in the timinggears during the calibration process.
-
STMG 672 - 41-4/97
34
Timing calibration
Nulls out smallcrankshaft to timinggear tolerances
REFERENCE EDGE TO TDC DISTANCE
REFERENCEEDGE ASSUMED
CYL. NO. 1 TDCACTUAL
CYL. NO. 1 TDC
TIMINGREFERENCE
OFFSET
MAXIMUM TIMING REFERENCE OFFSET 10 DEGREES
TIMING CALIBRATIONSENSOR SIGNAL
TIMINGWHEEL
TIMING CALIBRATION
+10
10
-10
As the Speed/Timing Sensors use the timing wheel for a timing
reference,timing calibration improves fuel injection accuracy by
correcting for anyslight tolerances between the crankshaft, timing
gears and timing wheel.
During calibration, the offset is logged in the control module
EEPROM(Electrically Erasable Programmable Read Only Memory).
Thecalibration offset range is limited to 10 crankshaft degrees. If
timing isout of range, calibration is aborted. The previous value
will be retainedand a diagnostic message will be logged.
Timing calibration is normally performed after the following
procedures:
1. ECM replacement
2. Speed/timing sensor replacement
3. Timing wheel replacement
-
STMG 672 - 42-4/97
35
Unit injector currentflow
INJECTION CURRENT WAVEFORM
0 1 2 3 4
CU
RR
EN
T
FL
OW
TIME (MILLISECONDS)
PULL-IN PEAK CURRENT
HOLD-IN PEAK CURRENT
ONE CYCLE
5
This illustration shows how the current increases initially to
pull in theinjection coil and close the poppet valve. Then, by
rapidly chopping(pulsing) the 105 Volts on and off, current flow is
maintained. The end ofinjection occurs when the current supply is
cut off and hydraulic pressuredrops. Therefore, fuel pressure drops
rapidly in the injector.
INSTRUCTOR NOTE: This waveform may be demonstrated with a9U7330
Digital Multimeter (or equivalent) and a current probe.
-
STMG 672 - 43-4/97
36
Poppet valvemovement
POPPET VALVE MOVEMENT
0 1 2 3 4
CU
RR
EN
T
FL
OW
TIME (MILLISECONDS)
CURRENT
POPPETLIFT
5
This diagram shows that the poppet valve will open just after
the ECMenergizes the solenoid. The poppet valve permits hydraulic
oil to shift theinjector intensifier piston which then moves the
injector plunger.
-
STMG 672 - 44-4/97
37
Timing relative to:
1. Injector currentflow
2. Poppet valvemovement
3. Injection rate
WAVEFORM AND RESPONSE CHARACTERISTICS
0 1 2 3 4
CU
RR
EN
T
FL
OW
TIME (MILLISECONDS)
CURRENT
POPPETLIFT
INJECTIONRATE
START OFINJECTION
DURATION
5
END OFINJECTION
Here timing is graphically illustrated to show:
1. The ECM initiates the signal to the injector to start
injection.
2. The injector solenoid opens the poppet valve.
3. The injection rate increases.
-
STMG 672 - 45-4/97
Fuel system limits
Variable horsepower
Economy Shift Mode
38
FUEL SYSTEM COLD MODES
Speed Control
Fuel Limiting Injection Timing Injection Actuation Pressure
Ether Injection
Just as the MUI engine had mechanical limits to determine
maximum fueldelivery during full load, full torque and
acceleration, the HEUI systemalso has electronic limits to protect
the engine. These limits are:
- Maximum Horsepower
- Torque Limit (Determines torque rise characteristics)
- Fuel Ratio Control (Limits fuel until sufficient boost is
available)
- Cold Mode Limit (Limits fuel with cold engine to control
whitesmoke)
- Cranking Limit (Limits fuel during cranking)
An acceleration delay during start-up holds the engine at low
idle for twoseconds or until oil pressure reaches 140 kPa (20
psi).
Off-highway Trucks have a system which increases engine
horsepower indirect drive only. This system protects the driveline
from excessivetorque in the lower gears.
Off-highway Trucks also have a service tool programmable feature
whichis designed to lower shift points and the fuel limit to
improve fuelconsumption at the customer's request.
-
STMG 672 - 46-4/97
Cold modes
39
FUEL SYSTEM COLD MODES
Speed Control Fuel Limiting Injection Timing Injection Actuation
Pressure Ether Injection
The HEUI fuel system is designed to modify the
operationalcharacteristics of the engine during cold operation.
This modification isdone to protect the environment, the engine and
to improve theoperational characteristics of the engine.
INSTRUCTOR NOTE: The various Cold Modes are tabulated
inServiceman's Handout No. 2. Discuss how these Cold Modevariations
can change the engine characteristics, particularly
duringdiagnostic operations. For example:
- Injection actuation pressure will vary with engine
temperature.
- Engine speed may be raised in Cold Mode.
-
STMG 672 - 47-4/97
Fuel system derates
Power correction
40
FUEL SYSTEM DERATES
Automatic Altitude Compensation
Automatic Filter Compensation
Engine Warning Derate
As the system limits fuel for every condition, derates are also
built intothe system for protection. These derates are individually
covered later inthe presentation, but are summarized here:
- Automatic Altitude Compensation (Altitude derate)
- Automatic Filter Compensation (Derates for air filter
restriction ifinstalled)
- Engine Warning Derate (Derates for low oil pressure and
highcoolant temperature; not installed on all applications)
If a loss of boost sensor output occurs, the ECM assumes zero
boostpressure. Although not strictly a derate, power is reduced
byapproximately 50 to 60%.
- Fuel Temperature Compensation (Compensates up to 5% forpower
loss caused by hot fuel)
-
STMG 672 - 48-4/97
INSTRUCTOR NOTE: This material will be reinforced if
thefollowing ET tasks are demonstrated. Review the material
withquestions following the tasks. The demonstration can be
performedon an engine or machine with a laptop computer. The
suggestedtopics are:
Basic ET review (if required)
Status screens with throttle switch status, desired engine
speed,fuel position, injection actuation pressure, etc.
Active diagnostic codes
Logged diagnostic codes
Events screen
Configuration screen
Timing calibration
Injector solenoid test
Cylinder cutout
Automatic injector test
-
STMG 672 - 49-4/97
41
FUEL INJECTION SYSTEM
FUEL INJECTION SYSTEM
This portion of the presentation describes the principles of
operation ofthe HEUI Fuel Injection System as is used on the 3408E
and 3412Eengines.
INSTRUCTOR NOTE: The various color codes which will be usedin
this section of the presentation to identify flow and pressures
are:
Hydraulic and Lubrication Circuits
Red - High pressure oil
Red and White Stripes- Reduced pressure oil
Brown - Lube oil pressure
Green - Lube oil suction or return
Fuel Circuits
Red - High pressure fuel
Red and White Stripes- Fuel transfer pump pressure
Green - Fuel suction or return
-
STMG 672 - 50-4/97
42
PUMPCONTROL
VALVE
OILFILTER
OILCOOLER
HEUI
HEUI
OILSUMP
HYDRAULICPRESSURE
SENSOR
HYDRAULICTEMPERATURE
SENSORCOLD START
OILRESERVOIR OIL PRESSURE
SENSOR
ECM
HYDRAULICSUPPLY
PUMPGROUP
COOL DOWNCIRCUIT
FUEL TANK
FUELTEMPERATURE
SENSOR
PRESSUREREGULATING
VALVE
SECONDARYFUEL
FILTER
FUELTRANSFER
PUMP
PRIMARYFUEL FILTER
WATERSEPARATOR
LUBE OILPUMP
TO LUBESYSTEM
3408E/3412E HEUI FUEL SYSTEM
FLUID MANIFOLDHYDRAULIC PASSAGE
FLUID MANIFOLDHYDRAULIC PASSAGE
Actuation of the fuel injection system is accomplished using
hydraulics,rather than the conventional camshaft actuation commonly
found on otherdiesel fuel systems.
Hydraulic actuation offers several advantages compared to
mechanicalactuation, including the ability to make injection
pressure independent ofengine operating speed. This capability is
especially advantageous inmany respects, including transient engine
response, cold starting,emissions and noise control.
INSTRUCTOR NOTE: The following schematics may appearidentical in
the black and white illustrations. However, the actualslides are
colored differently.
-
STMG 672 - 51-4/97
HEUI principlecomponents:
1. Hydraulic supplypump group
2. ECM
3. Temperaturesensor
4. Pressure sensor
5. Injector
43
12
3
54
System Components
To review, the 3400 HEUI hydraulic and fuel supply circuits
contain thefollowing major components:
Hydraulic Supply Pump Group (1) including:
- Hydraulic pump
- Fuel transfer pump
- Pump control valve
Electronic Control Module (ECM) (2)
Electronic Sensors (3 and 4)
- Hydraulic temperature
- Hydraulic pressure
Injectors (5)
-
STMG 672 - 52-4/97
Hydraulic supplypump group:
1. Hydraulic pump
2. Pump control valve
3. Transfer pump
44
1
2
3
The following components are integrated into a single unit
called theHydraulic Supply Pump Group:
- Hydraulic pump (1)
- Pump control valve (2)
- Transfer pump (3)
This pump group is located in the vee of the engine and is in
the sameposition as the fuel injection pump on earlier engines.
Three fluid circuits are included in the system: low pressure
oil, highpressure oil (hydraulic), and low pressure fuel
supply.
NOTE TO THE INSTRUCTOR: These components and circuits willbe
covered in detail later in the presentation.
-
STMG 672 - 53-4/97
45
Low pressure oilsupply
Cold start reservoir
Pressure sensor
Temperature sensor
TO LUBESYSTEM
FUELTRANSFER
PUMP
PUMPCONTROL
VALVE
OILFILTER
3408E/3412E HEUI FUEL SYSTEM
OILCOOLER
HEUI
HEUI
OILSUMP
HYDRAULICPRESSURE
SENSOR
HYDRAULICTEMPERATURE
SENSOR
OIL PRESSURESENSOR
ECM
COOL DOWNCIRCUIT
LOW PRESSURE OIL (HYDRAULIC) SUPPLY
FUEL TANK
FUELTEMPERATURE
SENSOR
PRESSUREREGULATING
VALVE
SECONDARYFUEL
FILTERPRIMARY
FUEL FILTERWATER
SEPARATOR
LUBE OILPUMP
COLD STARTOIL
RESERVOIR
HYDRAULICSUPPLY
PUMPGROUP
FLUID MANIFOLDHYDRAULIC PASSAGE
FLUID MANIFOLDHYDRAULIC PASSAGE
System Operation
On a HEUI equipped engine, the lubrication pump has two
functions:
1. Provides lubrication to the engine2. Provides low pressure
charge oil to the HEUI hydraulic pump
The engine lubrication pump has been enlarged to provide the
requiredincrease in flow.
The hydraulic pump has a Cold Start Oil Reservoir. This
reservoirprevents the hydraulic pump from cavitating during initial
enginecranking until the lubrication pump can supply adequate
charge pressure.
An oil pressure sensor is located in the Cold Start Oil
Reservoir, which isthe inlet to the hydraulic oil pump. The sensor
monitors lubrication oilpressure. An oil temperature sensor is also
installed in the reservoir. Thissensor will be referred to as the
"hydraulic temperature sensor" as it isused for this purpose.
-
STMG 672 - 54-4/97
46
High pressureactuates hydraulics
TO LUBESYSTEM
FUELTRANSFER
PUMP
PUMPCONTROL
VALVE
OILFILTER
3408E/3412E HEUI FUEL SYSTEM
OILCOOLER
HEUI
HEUI
OILSUMP
HYDRAULICPRESSURE
SENSOR
HYDRAULICTEMPERATURE
SENSOR
OIL PRESSURESENSOR
HYDRAULICSUPPLY
PUMPGROUP
COOL DOWNCIRCUIT
HIGH PRESSURE HYDRAULICS
FUELTEMPERATURE
SENSOR
ECM
FUEL TANK
PRESSUREREGULATING
VALVE
SECONDARYFUEL
FILTERPRIMARY
FUEL FILTERWATER
SEPARATOR
LUBE OILPUMP
COLD STARTOIL
RESERVOIRFLUID MANIFOLD
HYDRAULIC PASSAGE
FLUID MANIFOLDHYDRAULIC PASSAGE
During normal operation conditions, oil is pressurized
between5000 and 21500 kPa (725 and 3100 psi) by the high pressure
hydraulicpump to actuate the injectors. The level of hydraulic
pressure iscontrolled by the ECM, which signals the pump control
valve to upstrokethe hydraulic pump.
When the engine is running, high pressure oil is available to
all injectorsat all times.
Oil from the high pressure pump enters the two oil supply
passages.
Reverse flow check valves are used to prevent pressure surges
betweenthe oil passages on opposite banks. The oil supply passages
are connectedhydraulically to the injectors by jumper tubes. Oil
used by the injectors isreleased below the valve covers and drains
back to the sump through thepushrod compartments.
-
STMG 672 - 55-4/97
47
Low pressure fuelsupply
Injector cooling
TO LUBESYSTEM
FUELTRANSFER
PUMP PRESSUREREGULATING
VALVE
PUMPCONTROL
VALVE
OILFILTER
3408E/3412E HEUI FUEL SYSTEM
OILCOOLER
LUBE OILPUMP
HEUI
HEUI
OILSUMP
HYDRAULICPRESSURE
SENSOR
HYDRAULICTEMPERATURE
SENSOR
OIL PRESSURESENSOR
ECM
COOL DOWNCIRCUIT
LOW PRESSURE FUEL SUPPLY
FUELTEMPERATURE
SENSOR
FUEL TANK
SECONDARYFUEL FILTER(2 MICRON)
PRIMARYFUEL FILTER
WATERSEPARATOR
COLD STARTOIL
RESERVOIR
HYDRAULICSUPPLY
PUMPGROUP
FLUID MANIFOLDHYDRAULIC PASSAGE
FLUID MANIFOLDHYDRAULIC PASSAGE
Fuel is drawn from the tank through the water separator and the
handpriming pump by a gear-type transfer pump. The fuel is then
directedthrough the Electronic Control Module (ECM) housing for
coolingpurposes. The fuel then flows through the secondary fuel
filter.
Next, the fuel enters the low pressure supply gallery located in
the fluidsupply manifolds on top of the cylinder heads. Any excess
fuel notinjected leaves the manifold. The flow is then combined
into one line andpasses through the pressure regulating valve,
which is set between310 and 415 kPa (45 and 60 psi). From the
pressure regulating valve, theexcess flow returns to the tank. The
ratio of fuel between combustion andfuel returned to the tank is
about 1:3 (i.e. four times the volume requiredfor combustion is
supplied to the system for combustion and injectorcooling
purposes).
A fuel temperature sensor is installed in the fuel supply system
tocompensate for power losses caused by varying fuel
temperatures.
-
STMG 672 - 56-4/97
48
Fuel and oil flow
LOW PRESSUREFUEL SUPPLY
CYLINDER HEADINJECTOR SLEEVE
FLUID SUPPLYMANIFOLD
INJECTOR
INJECTOR OILADAPTER
JUMPER TUBE
INJECTOR CLAMP
HIGH PRESSUREHYDRAULIC PASSAGE
CYLINDER HEAD
ROCKER ARM BASE
LUBE OIL PASSAGE
CYLINDER BLOCKCOOLANT
METAL WASHER
INJECTOR FLUID FLOW HIGH PRESSURE HYDRAULIC OIL
Hydraulic Unit Injector Operation
High pressure hydraulic oil is provided to each injector from
the hydraulicsupply passages through individual jumper tubes.
Fuel is supplied to the injector by the low pressure supply
passage locatedin the fluid manifolds (described on the next
slide).
Special "Viton" o-rings are used in the hydraulic joints between
theinjector and the fluid manifold.
NOTE: This slide and the following slide depart from the
colorlegend by using orange for high pressure oil to avoid
confusionbetween the two fluids.
-
STMG 672 - 57-4/97
49
Low pressure fuelsupply to injector
FLUID SUPPLYMANIFOLD
INJECTOR
CYLINDERHEAD
LOWER INJECTORO-RING SEAL
UPPER INJECTORO-RING SEAL
INJECTOR FUEL SUPPLY
METAL-TO- METALCONTACT
LOW PRESSUREFUEL SUPPLY
CYLINDER HEADINJECTOR SLEEVE
UPPER SLEEVEO-RING SEAL
LOWER SLEEVEO-RING SEAL
Low pressure fuel is supplied to the inlet of the injector
through a drilledpassage located in each Fluid Supply Manifold.
The fuel supply to each injector is sealed from the combustion
chamberand the area below the valve cover by upper and lower o-ring
sealsbetween the injector and the cylinder head injector
sleeve.
Combustion chamber gases are prevented from entering the fuel
supplypassage by a metal-to-metal contact between the cylinder head
injectorsleeve and the injector.
The cylinder head injector sleeve is threaded into the cylinder
head. Ametal washer is used to seal the lower end of the adapter to
preventleakage between the cooling system and the combustion
chamber.
-
STMG 672 - 58-4/97
Fluid supply manifold
Supply passages:
1. Hydraulic
2. Lubrication
3. Fuel
50
21 3
The following passages are located in the Fluid Supply
Manifold:
- Hydraulic supply passage (1)
- Lubrication supply passage (2)
- Fuel supply passage (3)
The fluid supply manifold is mounted on the cylinder head and
carriesinjector actuation hydraulic oil under pressure through the
jumper tubes tothe injectors.
Low pressure fuel and lubrication oil to the valve mechanism are
alsodirected through the manifold. These passages are shown in the
sectionalview on the next slide.
-
STMG 672 - 59-4/97
51
Supply passages
Additional fuel forcooling
Fuel seals
LOW PRESSUREFUEL SUPPLY PASSAGE
CYLINDER HEADINJECTOR SLEEVE
HIGH PRESSUREHYDRAULIC PASSAGE
ROCKER ARMBASE
LUBRICATION OILPASSAGE
EXTRACTORSPLINES
FUEL SEALS
FLUID SUPPLY MANIFOLD
This sectional view shows the various passages in the Fluid
SupplyManifold.
- High pressure hydraulic supply passages
- Low pressure fuel supply passages
- Lubrication oil supply passages
The fuel enters the front of the manifold and exits the rear.
Cooling of theinjectors is achieved by circulating a larger volume
of fuel past theinjectors than is required for combustion.
Initially, fuel circulates around the outside of the injector
sleeve and iscontained between the sleeve and the fluid supply
manifold by the upperand lower injector sleeve fuel seals.
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STMG 672 - 60-4/97
Jumper tube and oiladaptor
52
1
2
The Jumper Tube (1) and Injector Oil Adaptor (2) direct
hydraulic oilfrom the fluid manifold high pressure passage to the
injector.
A specific procedure to tighten the six bolts (for the Jumper
Tube andAdaptor) must be followed when installing the jumper tube.
Thisprocedure follows later in the presentation.
NOTICEFailure to follow the correct tightening procedure can
result in lowpower complaints caused by internal hydraulic leaks.
Also, internalstrains on the injector caused by an improper
tightening procedurecan cause changes in internal injector
clearances which can decreaseperformance and injector life.
-
STMG 672 - 61-4/97
53
Injector currentwaveform
Two current levels
INJECTION CURRENT WAVEFORM
0 1 2 3 4
CU
RR
EN
T
FL
OW
TIME (MILLISECONDS)
PULL-IN PEAK CURRENT
HOLD-IN PEAK CURRENT
ONE CYCLE
5
Injector Operation Characteristics
The quantity of fuel delivered is controlled by varying the time
thesolenoid is energized. This period of time, called "duration,"
is calculatedby the ECM to ensure delivery of the correct amount of
fuel. Other inputsaffect calculation of on-time, including (but not
limited to) hydraulicsupply pressure, oil temperature and mapped
injector performancecharacteristics. Two current levels are
generated in the wave form:
1. Pull-in current is higher to create a stronger magnetic field
toattract the armature and lift the injector poppet valve off its
seatagainst spring force.
2. Hold-in current is used to hold the armature and poppet off
itsseat. Lower current reduces heat in the solenoid and
increasessolenoid life.
The injector performance map shows delivery as a function of
on-time,pump pressure, and oil temperature, and is stored in the
ECM memory.
-
STMG 672 - 62-4/97
54
Waveform and injectorresponse
WAVEFORM AND RESPONSE CHARACTERISTICS
0 1 2 3 4
CU
RR
EN
T
FL
OW
TIME (MILLISECONDS)
CURRENT
POPPETLIFT
INJECTIONRATE
START OFINJECTION
DURATION
5END OF
INJECTION
This slide shows that, as the ECM energizes the solenoid, the
poppet valvemovement follows. Then, the injector rate increases for
the start ofinjection. The end of injection occurs as the rate
drops toward zero.
Therefore:
Engine fuel timing is a function of the start of injection.
Fuel quantity is a function of:
- The duration of injection - Injection actuation (hydraulic)
pressure
-
STMG 672 - 63-4/97
Pull-in current
Poppet lift - Blue line
Start of injection- Purple line
Injection rate - Purple line
End of injection
The ECM sends a higher current to the solenoid to create a
strongmagnetic field. This strong field is needed to create maximum
pull on thearmature, which is at its farthest distance from the
solenoid.
The poppet is normally held on its inlet seat by the poppet
spring. Thehigher pull-in current attracts the armature and lifts
the poppet off its inletseat and toward the exhaust seat against
the spring force. The ECMreduces the current level to hold-in
current and the poppet is held on itsexhaust seat.
Injection starts after the exhaust seat closes and oil pressure
pushes theintensifier piston and plunger down. The downward
movement of theplunger pressurizes the fuel to approximately 31000
kPa (4500 psi) andthe check valve lifts, allowing fuel to enter the
cylinder. The time atwhich fuel leaves the tip is called the "start
of injection."
The rate at which fuel is injected is controlled by injection
hydraulicpressure. Higher hydraulic pressure pushes the piston and
plunger faster,causing a higher flow rate through the nozzle
tip.
When the ECM ends injection, it terminates the hold-in current
whichcauses the magnetic field in the solenoid to collapse. The
poppet springthen moves the poppet back to the inlet seat. As the
poppet travels backto the inlet seat, hydraulic oil is shut off,
and the downward travel of thepiston and plunger reverses, filling
the barrel for the next injectionsequence.
As pressure drops below the plunger and nozzle areas, the valve
closingpressure, which is about 21000 kPa (3000 psi), causes this
pressure to beretained in the nozzle for the next cycle.
INSTRUCTOR NOTE: If a disassembled or a cutaway injector
isavailable, it is recommended that the preceding sequence be
reviewedusing the actual components.
-
STMG 672 - 64-4/97
Major components
Seals
55
Injector Components
The 3408E/3412E unit injector has been designed to represent the
state ofthe art in the industry. This section of the presentation
will describe allthe components and their functions.
This slide shows a cutaway injector and the injector sleeve.
Note thefollowing major injector component groups:
- Valve body group with solenoid and poppet valve
- Barrel group with intensifier piston and plunger
- Nozzle group
The injector sleeve has four seal grooves. The two upper grooves
havethe seals which contain the fuel within the fluid manifold
(shown in moredetail later).
The two lower seals contain the coolant below the cylinder upper
deck. Ametal washer seals the lower part of the sleeve and prevents
coolant fromentering the combustion chamber.
-
STMG 672 - 65-4/97
56
Three main groups
HEUI UNIT INJECTOR
3 MAIN GROUPS
VALVE BODYGROUP
BARREL GROUP
NOZZLE GROUP
The injector consists of three basic groups which will be
described indetail:
- Valve Body Group
- Barrel Group
- Nozzle Group
This view and those that follow show the exhaust port on the
injectorventing the return oil downward. This condition is a
modification fromthe previous design which vented the oil upward.
These injectors areinterchangeable. However, the newer injector
reduces the tendency of theengine to discharge oil mist from the
breather.
-
STMG 672 - 66-4/97
57
Injector components
STOPPINPLUNGER SPRING SEAL BARREL BALL
DOWEL
SEAL
INTENSIFIER PISTON
RETAINER RING
WASHER
STOPPLATE
CHECKPLATE
BALL
STOP
DOWEL
SPRING
LIFTSPACER
SLEEVE
DOWEL
CHECK
TIP CASE
POPPET SPRING SLEEVE SHIM SEAL
ADAPTER BOLT
SPACER
ARMATURE
SCREW
SOLENOIDASSEMBLY
SCREW
BODYVALVE BODY GROUP
BARREL GROUP
NOZZLE GROUP
3408E/3412E HEUI INJECTORCOMPONENTS
The HEUI injector was designed with a minimum of component
parts.The injector contains 35 part numbers.
This exploded view shows all the components by assemblies as
follows:
The Valve Body Group contains the solenoid, armature and the
poppetvalve. This assembly directs the oil to the hydraulic
intensifier pistonwhich moves the fuel plunger.
The Barrel Group contains the high pressure fuel plunger.
The Nozzle Group contains the case, tip, check valve and
nozzle.
NOTE: Although the injector components are explained in
thispresentation, it should be noted that no individual parts of
theinjector are serviced. This injector is precision assembled by
amachine, and replacing individual injector components would
resultin unacceptable performance problems or injector
failures.
-
STMG 672 - 67-4/97
58
Injector componentparts
SHIMBARREL
PISTON
VALVE
FUEL INLETCHECK VALVE
PIN
SPACER
ADAPTER
SPACER
ARMATURE
SOLENOID
WASHER
PLUNGER
SLEEVE
SLEEVE
UNIT INJECTOR COMPONENTS
LOWER FUEL SEAL
VALVE BODY
UPPER FUEL SEAL
NOZZLE
CHECK
This slide shows the component parts in the three basic groups
discussedpreviously.
The valve body has three parts (body, adaptor and spacer) which
areassembled with great precision. Any damage sustained in the
valve bodyarea during installation or removal will cause an
injector failure.
NOTICEThe correct injector removal procedures and tooling
specified in theservice manual must always be used. Any leverage
applied below thevalve body can cause deformation of the poppet
valve bore andpossible injector failure.
-
STMG 672 - 68-4/97
59
HORIZONTALBOLTS
JUMPER TUBE
INJECTOR CLAMP
VERTICALBOLTS
INJECTOR INSTALLATIONALLEN
SCREWS
INJECTOR OILADAPTOR
Injector Removal and Installation
The correct procedures for injector removal and installation
must befollowed to avoid strain on the injector and hydraulic leaks
in the jumpertube area. The three mating surfaces of the jumper
tube, oil adaptor andinjector must be aligned before final torque
is applied.
INSTRUCTOR NOTE : At this time, it is recommended that
theinjector removal and installation procedures be
demonstrated.Emphasis should be placed on the use of the correct
puller duringremoval (rather than a pry bar, which could result in
injectordamage). Also, disassemble a used injector to identify the
variouscomponents shown on this slide.
-
STMG 672 - 69-4/97
Injector assembly andinstallation
This portion of the assembly procedure ensures that all mating
and sealingfaces are flush and in complete contact before
tightening the bolts.
1. Clean the faces of the injector and the injector sleeve and
installnew o-rings.
2. Lubricate the o-rings with oil and insert the injector in the
injectorsleeve.
3. Visually align the injector with the flat surface parallel to
thecenterline of the engine.
4. Position the injector clamp on the injector and tighten the
bolt to 47 9 Nm (35 7 lb. ft.).
5. Install new seals on the jumper tube and rocker arm base.
6. Place the injector oil adaptor and jumper tube in
position.
7. Install the allen screws and hex head bolts finger tight. If
theinjector oil adaptor was previously installed on the injector,
loosenthe allen screws.
The objective at this point in the procedure is to bring all the
mating facesinto complete contact and alignment before starting the
final torqueprocedure.
Failure to align the components will put a strain on the
injector which willthen distort the poppet valve and barrel bores.
These components operatewith a clearance of 5 microns because of
the high injection and hydraulicpressures. Therefore, even a small
amount of distortion will cause aseizure.
Additionally, some misalignment could cause combustion gases to
enterthe supply system.
-
STMG 672 - 70-4/97
Injector installationtorque sequence
After all the mating surfaces are aligned, the torquing
procedure can beperformed:
1. Tighten the allen screws and hex head bolts finger tight or
justsufficiently to bring the mating surfaces together and
intoalignment.
2. Apply an initial torque to the vertical hex head bolts of 5 3
Nm(4 2 lb. ft.).
3. Apply an initial torque to the horizontal hex head bolts of 5
3 Nm (4 2 lb. ft.).
4. Apply an initial torque to the allen screws of 1 0.2 Nm (10 2
lb. in.).
5. Final torque the vertical hex head bolts to 47 9 Nm (35 7 lb.
ft.).
6. Final torque the horizontal hex head bolts to 47 9 Nm (35 7
lb. ft.).
7. Final torque the allen screws to 12 3 Nm (9 2 lb. ft.).
8. Check the system for leaks (crank with injection disabled).
Then,check the hydraulic pressure (compare with desired
pressure).
A number of possibilities for leaks can exist. Oil under high
pressure mayleak from the jumper tube joints or from the injector
valve body exhaustport. Fuel could leak from the upper seal on the
injector. Also,combustion gas can possibly leak from the base of
the injector.
If air has entered the fuel supply system, multiple injectors on
one bankmay malfunction. If the above procedure was not followed,
air couldenter past the lower o-ring seal. If this condition
occurs, remove theinjector and check for carbon below the lower
o-ring seal. Replace theseal and perform the torque sequence.
Air in the system may be detected by lightly touching the
flexible returnline and checking for extreme pulsations or pressure
spikes felt throughthe line. As an alternative, install a sight
glass in each return line, run theengine and check for air.
Combustion gas leakage will usually affect the injector with the
leakfollowed by the injectors downstream (toward the rear) of the
leak.
In conclusion, the system is reliable. However, failure to
follow theseprocedures may cause malfunctions.
-
STMG 672 - 71-4/97
60
Solenoid de-energized
Solenoid energized
Oil flows to intensifierpiston
SOLENOID DE-ENERGIZED SOLENOID ENERGIZEDPOPPET VALVE CLOSED
POPPET VALVE OPEN
ARMATURESCREWPOPPET
SPRINGINLET
VALVE SEAT
SOLENOID
POPPET VALVE
ARMATURE
EXHAUSTVALVE SEAT
VALVE BODY GROUP
Injection Sequence
When the solenoid is de-energized, the poppet valve is held on
its inlet(left) seat by the poppet spring. The poppet valve is
connected to thearmature by the armature screw. When the poppet is
closed, the inlet seatprevents high pressure oil from entering the
injector. The exhaust poppetseat is open, connecting the
intensifier piston cavity to the atmosphere.
Based on input signals from the various electronic sensors, the
ECMcalculates the quantity and timing of fuel to be delivered by
the injector tothe combustion chamber. At the appropriate time, the
ECM sends anelectrical current to the injector solenoid.
The solenoid develops a magnetic force which attracts the
armature andshifts the poppet valve. The poppet valve moves against
the spring force,opens the inlet seat and closes the exhaust
(right) seat. Hydraulic pressureoil from the supply manifold is
directed through the jumper tube to the topof the intensifier
piston.
-
STMG 672 - 72-4/97
61
Plunger moves down
Pressurizes fuel belowplunger
Pressureintensification
FUEL INLETCHECK VALVE
INTENSIFIERPISTON
PLUNGER
FUEL TONOZZLE
BARREL
BARREL GROUPFUEL PRESSURE INCREASE
REVERSE FLOWCHECK VALVE
FUEL FROMTRANSFER PUMP
SUPPLY OIL
Supply oil flow from the poppet valve causes the intensifier
piston and thefuel plunger to move downward. The displacement of
the plungerpressurizes the fuel trapped between the plunger face
and the nozzle checkseat.
NOTE: The intensifier piston has almost seven times the area of
thefuel plunger. When the hydraulic circuit is supplying a pressure
of21000 kPa (3000 psi), approximately 145000 kPa (21000 psi) will
begenerated below the fuel plunger.
-
STMG 672 - 73-4/97
62
Fuel atomization
VIEW OF STOP PLATE & REVERSE FLOW CHECK VALVE
REVERSE FLOWCHECK VALVE
FUEL ATOMIZATION
NOZZLE GROUP
CHECK VALVE
When the trapped pressure exceeds the nozzle valve opening
pressure(VOP), typically 31000 kPa (4500 psi), the check valve
lifts, and fuelflows through the holes in the nozzle into the
combustion chamber. At theend of injection, the nozzle check valve
closes at approximately21000 kPa (3000 psi).
The reverse flow check valve is used to prevent combustion
induced gasflow from entering the nozzle area.
The nozzle of the injector is very similar to the EUI unit
injector. Sixorifices, each with a diameter of 0.252 mm (.010 in.),
are arranged at anangle of 140 degrees.
-
STMG 672 - 74-4/97
63
End of injection
Solenoid de-energized
Poppet valve closes
INLETVALVE SEAT
SOLENOID
POPPET VALVE
ARMATURE
EXHAUSTVALVE SEAT
SOLENOID DE-ENERGIZED
VALVE BODY GROUP
The end of injection is accomplished by shutting off the current
from theECM to the injector solenoid. The resulting loss of
magnetic force on thearmature allows the return spring force to
shift the poppet valve off theexhaust seat.
The poppet returns to the inlet seat in the valve body, blocks
the flow fromthe hydraulic oil supply, and simultaneously fully
opens the exhaust valveseat. This action vents the injector
internal hydraulic circuit below thevalve cover.
-
STMG 672 - 75-4/97
64
End of injection
Intensifier pistonmoves up
Nozzle check valvecloses
SHIM
BARREL
PISTON
VALVE
BALL
PIN
SPACER
ADAPTER
SPACER
ARMATURE
SOLENOID
WASHER
PLUNGER
SLEEVE
SLEEVE
NOZZLE
BODY
UNIT INJECTOREND OF INJECTION
CHECK
When vented, the intensifier piston and fuel plunger are pushed
upwardby the plunger return spring force until the intensifier
piston contacts thevalve body. This upward displacement of the
intensifier piston ventsspent oil from the injector below the valve
cover.
Retraction of the fuel plunger decreases the pressure in the
fuel chamberbelow the plunger, which permits the nozzle check valve
to close whenthe pressure in the nozzle drops below the valve
closing pressure (VCP)of approximately 21000 kPa (3000 psi).
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STMG 672 - 76-4/97
65
Barrel refilling
BARREL GROUPREFILLING THE BARREL
BARREL
PISTON
FUEL INLETCHECK VALVE
PIN
SPACER
WASHER
PLUNGER
SLEEVE
NOZZLE
NOZZLE CHECKVALVE
FUEL EDGEFILTER
As the plunger continues to retract, the pressure below the
plungerdecreases below the fuel supply gallery pressure. The fuel
inlet checkvalve then opens, allowing fuel to pass through the edge
filter (next slide)to the supply gallery to refill the injector for
the next injection sequence.
-
STMG 672 - 77-4/97
66
Fuel edge filter
REVERSE FLOWCHECK VALVE
EDGE FILTER
EDGE FILTER
FUEL INLETCHECK VALVE
FUEL INLET FUEL INLET
Note the location of the fuel edge filter. The edge filter is
formed by twoflat parallel surfaces that are approximately 130
microns apart. Thesesurfaces trap and break down particles which
might be big enough to plugthe nozzle orifices.
-
STMG 672 - 78-4/97
67
Injection rate shaping
Low emission levels
PRIME
PRIME INJECTION RATE SHAPING
0 1 2 3 4TIME (MILLISECONDS)
5
PRIME = PRE-INJECTION METERING INJECTION RATE
DURATIONSTART OF INJECTION
Another feature used in the injector for 3408E/3412E
applications is aninjection rate shaping device. Rate shaping
refers to tailoring the way fuelis delivered to the engine to
obtain a desirable result. In the 3408E/3412Eapplication, rate
shaping reduces the quantity of fuel delivered to thecombustion
chamber during the ignition delay period (i.e. the timebetween the
start of injection and start of combustion) to levels whichproduce
low engine combustion noise and low emissions.
The device used to create rate shaping is known as PRIME,
anabbreviation for PRe-Injection MEtering. This device is basically
acontrolled spill port which serves to limit the amount of fuel
delivered tothe combustion chamber during the initial 25%
displacement of the fuelplunger. This metering action produces the
desired reduction of fueldelivery during the ignition delay
period.
-
STMG 672 - 79-4/97
68
Injection rate shaping
1. Start of injection
2. Pressure drop
3. Final increase
Benefits
CROSS SECTIONOF PLUNGER
PRIME RATESHAPING PASSAGE
PLUNGER
BARREL
SPILLPORT
FUEL TONOZZLE GROUP
START OF INJECTION PRESSURE DROPFINAL
PRESSURE INCREASE
BARREL GROUPPRIME RATE SHAPINGOIL FLOW
This slide shows the three stages in PRIME rate shaping.
1. Injection pressure starts to increase and causes the
initialmovement of the plunger.
2. When the prime rate shaping passage on the plunger is passing
thespill port in the barrel, pressure decreases below VCP
aspressurized fuel leaks through the passage in the plunger into
thespill port. At this time, nozzle flow momentarily decreases.
3. As the plunger continues downward, the PRIME rate
passagepasses the spill port and pressure will again increase,
causinginjection to resume.
This feature reduces emissions, smoke and noise. It also
provides asmoother combustion cycle and reduces wear on the
cylinder components.
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STMG 672 - 80-4/97
69
Internal leakage
Fluids are vented topump inlet
BARREL GROUPVENTING INTERN