2 Learning ObjectivesDiscuss the various types of electronically controlled diesel fuel systemsDescribe why the current flow through an inductor can not instantly changeExplain the fundamentals of a closed loop control systemDiscuss how an in-range failure might not cause a DTC to be set
3 Learning Objectives (continued) Explain the difference between in-cylinder emission reduction and exhaust aftertreatmentDiscuss how a variable geometry turbocharger can be used to regulate EGR flow rateExplain how particulate matter and NOx exhaust emissions are controlledDescribe the requirements for HD-OBD and discuss some of the benefits of this regulation for technicians
4 Electronically Controlled Engine Particulate Matter (PM) – Exhaust smokeOxides of Nitrogen (NOx) – One of the pollutants responsible for smogElectronic Control Module (ECM) –Computer that controls engine fuel system
6 The Basic Tasks of a Diesel Fuel System Provide injection meteringAtomize the fuelProvide injection timing controlControl fuel delivery independent of engine speed and cam shaft geometryPerform multiple injection events per cycle
8 Bosch Electronically Controlled VE Distributive Pump Figure 14-6 Bosch electronically controlled VE distributor injection pump used on smaller diesel engines.
9 Electronic Unit Injector (EUI) NOP – Nozzle opening pressureNCV – Needle control valveSV – Spill valveEUP – Electronic unit pumpPilot Injection – Small amount of fuel injected in combustion chamber prior to main injection
10 Single Actuator EUIFigure 14-10Single actuator EUI.
11 Important FactThe 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.
12 Current Rise Figure 14-12 Instantaneous current rise in a resistor circuit.Figure Ramped current rise ininductor circuit
14 Nozzle Can Open When NCV is Energized Figure Nozzle opens when NCV is energized.
15 Electronic Unit Pump (EUP) Figure Electronic unit pump.
16 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 sensorElectronic unit injectors (EUI)High pressure oil manifold
17 Navistar HEUI Pressure Control System Components Figure Navistar HEUI injection pressure control system components.
18 Closed Loop Circuit ECM knows the desired injection control pressure ECM knows the measured or actual injection control pressureMeasured injection control pressure can be changed by increasing or decreasing the duty cycle of the injection pressure regulator
19 Navistar Single Coil Unit Injector Figure Navistar single coil HEUI injector internal components.
20 CAUTIONFollow the OEM’s specific safety recommendations when troubleshooting any electronically controlled diesel fuel system to prevent fatal electric shock.
22 WARNINGNever 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.
23 Caterpillar Common Rail Fuel System Figure Caterpillar common rail fuel system.
24 Common Rail High Pressure Pump with Control Solenoids Figure 14-28Common rail high-pressure pump with control solenoids.
25 Solenoid Controlled Common Rail Injector Nozzle Figure Solenoid-controlled common rail injector nozzle.
26 Piezo Actuated Common Rail Injector Figure Piezo-actuated common rail injector.
27 In Cylinder Exhaust Emission Reduction EGR – Exhaust gas recirculationVGT – Variable geometry turbochargerSmart Actuator – An actuator that contains a microprocessor and communication interfaceVirtual Sensor – Estimated value obtained from mechanical models of the systemLearn Cycle – Actuator is driven from minimum to maximum span at start up
28 Typical Cooled EGR System With VGT Turbocharger Figure Typical cooled EGR system with VGT.
33 Caterpillar CRS System Figure Caterpillar CRS system. Compressed air is used to purge the injector and to aid in combustion.
34 Caterpillar CRS Injector and Spark Plug Assembly Figure Caterpillar CRS injector and spark plug details. Engine coolant is used to cool the injector.
35 SCR System ComponentsFigure SCR system components.
36 Bosch Denoxtronic® System Figure Bosch Denoxtronic® system.
37 Heavy Duty On-Board Diagnostics HD-OBD – Heavy duty on board diagnosticsMIL – Malfunction indicator lampStarted coming into effect in 2010Pending DTC – ECM first detects an emissions related malfunction; MIL will not illuminateDetected DTC – The pending DTC is detected on second drive cycle; MIL will illuminate
38 Pro Link 9000 ESTFigure Pro-Link 9000 scan tool.
39 PC Based ESTFigure PC-based electronic service tool.
40 Injector Cut Out Test Result Figure Injector cutout test results indicate a problem with #2 cylinder.
41 Two Channel Oscilloscope Displays Two Different Signals Figure Two-channel oscilloscope displays two different signals.
42 Typical J1939 Voltage Levels Figure Typical J1939 voltage levels using two-channel oscilloscope referenced to ground.
43 SummaryVehicles 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.
44 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.
45 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.
46 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.
47 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.