 | |
| Illustration 1 | g01523669 |
Left side view (1) Fuel rail pressure sensor (2) Solenoid 1 for the high pressure fuel pump (3) Solenoid 2 for the high pressure fuel pump (4) Coolant temperature sensor (5) Intake manifold air temperature sensor (6) Crankcase pressure sensor (if equipped) (7) Intake manifold pressure sensor (8) Pilot fuel pressure sensor (9) Main fuel pressure sensor (10) Oil pressure sensor (11) Secondary speed/timing sensor (12) Primary speed/timing sensor | |
 | |
| Illustration 2 | g01607314 |
Right side view (13) Differential pressure sensor for the combustion air supply (14) Differential pressure sensor for the CGI system (15) Absolute pressure sensor for the CGI system (16) Air inlet temperature sensor (17) Temperature sensor for the CGI system (18) Flame boundary temperature sensor (19) Flame detection temperature sensor (20) Turbocharger outlet temperature sensor | |
 | |
| Illustration 3 | g01523671 |
Diesel Particulate Filter (DPF) (21) Inlet temperature sensor to the DPF (22) Electrical connector (23) Sensor group (24) Outlet temperature sensor for the DPF | |
The electronic control system is integrally designed into the engine's fuel system and the engine's air inlet and exhaust system in order to electronically control the fuel delivery and the injection timing. The electronic control system provides improved timing control and fuel air ratio control in comparison to conventional mechanical engines. Injection timing is achieved by the precise control of the injector firing time. Engine rpm is controlled by adjusting the injection duration. The Engine Control Module (ECM) energizes the unit injector solenoids in order to start the injection of fuel. Also, the ECM de-energizes the unit injector solenoids in order to stop the injection of fuel.
Refer to Systems Operation/Testing and Adjusting, "Fuel System" for a complete explanation of the fuel injection process.
The engine uses the following three types of electronic components:
- Input component
- Control component
- Output component
An input component is one that sends an electrical signal to the ECM of the system. The signal that is sent varies in either of the following ways:
- Voltage
- Frequency
- Pulse width
The variation of the signal is in response to a change in some specific system of the vehicle. Some specific examples of an input component are the engine speed-timing sensors, the coolant temperature sensor, and the cruise control switches. The ECM interprets the signal from the input component as information about the condition, environment, or operation of the vehicle.
A control component (ECM) receives the input signals from the input components. Electronic circuits inside the control component evaluate the signals from the input components. These electronic circuits also supply electrical energy to the output components of the system. The electrical energy that is supplied to the output components is based on predetermined combinations of input signal values.
An output component is one that is operated by a control module. The output component receives electrical energy from the control group. The output component uses that electrical energy in one of two ways. The output component can use that electrical energy in order to perform work. The output component can use that electrical energy in order to provide information.
As an example, a moving solenoid plunger will perform work. By performing work, the component has functioned in order to regulate the vehicle.
As an example, a dash panel light or an alarm will provide information to the operator of the vehicle.
These electronic components provide the ability to electronically control the engine operation. Engines with electronic controls offer the following advantages:
- Improvement in performance
- Improvement in fuel consumption
- Reduction in emissions levels
Operation of the Diesel Particulate Filter (DPF)
The DPF and the Aftertreatment Regeneration Device work together in order to reduce particulate emissions. The DPF collects the soot in the exhaust. The process of converting soot into gas is called regeneration. The Aftertreatment Regeneration Device helps to accomplish this process when regeneration is required. Ash from the engine oil is also collected in the DPF.
The DPF filters soot from the exhaust gas. If the temperature that is in the DPF is hot enough, the DPF converts the soot into gas. If the temperature that is in the particulate trap is not hot enough, the particulate trap retains the soot. Excessive soot can lead to plugging of the particulate trap. When the soot must be removed from the particulate trap, the electronic control module will activate the Aftertreatment Regeneration Device so that the soot can be oxidized into gas. Regeneration will be required more frequently when the engine is operated at extended idle and when the engine is operated in cold conditions. The particulate trap will need periodic cleaning of the accumulation of ash that occurs from the engine oil.
Operation of the Aftertreatment Regeneration Device
The temperature of the DPF must be above a particular value in order for regeneration to occur. The exhaust gas provides heat for the regeneration process. There are two types of regeneration:
Passive Regeneration - The engine provides sufficient exhaust gas temperature for regeneration.
Active Regeneration - The engine's duty cycle does not provide sufficient exhaust temperature for passive regeneration. The Aftertreatment Regeneration Device operates in order to raise the temperature of the exhaust gas. When the regeneration process is complete, the Aftertreatment Regeneration Device turns off.
Operation of the Clean Gas Induction (CGI)
The CGI system sends hot exhaust gas from the DPF to the cooler for the CGI. The hot exhaust gas is cooled in the CGI cooler. The now cooled exhaust gas passes through an electronic controlled flapper valve. The electronically controlled flapper valve is hydraulically actuated. The engine is using air from the truck's air filter system when the flapper valve is in the full OFF position. As the flapper valve starts to open the flow of cooled exhaust gas from the CGI cooler mixes with the air flow from the air filter. As the demand for more cooled exhaust gas increases the flapper valve opens wider. This increases the flow of cooled exhaust gas from the CGI cooler. As the demand for more cooled exhaust gas increases, the demand for air flow from the engine's air filter decreases.