S07.10-0031-79
Block diagram |
A1/1 | Instrument cluster (KI) control unit | N141 | AdBlue® (SCR) control unit | |
A97/1 | Control unit of NOx sensor upstream of SCR catalytic converter | R9 | Glow plugs | |
A97/2 | NOx sensor control unit downstream of SCR catalytic converter | X11 | Diagnostic connector | |
M3/3 | Fuel pump with fill level sensor | Y76 | Fuel injectors | |
N3/33 | CDI control unit | CAN D | Diagnostic CAN | |
N14/8 | Glow output stage | CAN HMI | User interface CAN | |
N15/3 | Electronic transmission control (EGS) control unit | CAN I | Drive train sensor CAN | |
N30/4 | Electronic Stability Program (ESP) control unit | CAN V | Vehicle CAN | |
N50 | Fuse and relay module control unit (SRM) | A | Mercedes-Benz | |
N50k8 | Fuel pump relay | B | Nissan | |
N93 | Central gateway (CGW) | C | Default | |
N118 | Fuel system control unit (FSCU) | D | Optional |
Common rail direct injection CDI, general
The common rail direct injection (CDI) regulates an optimal injection quantity under all operating conditions. The engine management takes place through the CDI control unit (N3/33).
The engine management is subdivided into the following systems:
Engine system
Diesel injection system
Air control system
Exhaust system
Engine system
Throttle valve control
Safety fuel shutoff
Transmission overload protection
Support of the Electronic Stability Program (ESP®)
Anti-jerk control
Glow time control
European On-Board Diagnosis II
Variant coding
Torque coordination
Alternator interface
Load determination
Maximum vehicle speed limit
Diesel injection system
Pre, main and post injection
Idle speed control
Smooth running control
Limp-home function
A/C rpm increase
Inertia fuel shutoff
Rail pressure regulation
Fuel pump controlling
Fuel high-pressure pump controller
Altitude adaptation
Rpm limitation
Glow system control
The CDI actuates the glow output stage (N14/8) over the CDI control unit (N3/33) . This in turn actuates the glow plugs (R9):
Cylinder 1 glow plug (R9/1)
Cylinder 2 glow plug (R9/2)
Cylinder 3 glow plug (R9/3)
Cylinder 4 glow plug (R9/4)
One differentiates between preglowing, start-up glowing and afterglowing.
Fuel supply
The fuel system control unit (FSCU) (N118) actuates the fuel pump with fill level sensor (M3/3), which delivers fuel via the fuel filter to the high-pressure pump. The quantity control valve (Y94/3) regulates the feed to the high-pressure pump to about 4.0 bar according to the actuation by the CDI control unit (N3/33).
Injection quantity control
The high-pressure pump pushes the fuel with an increased pressure in the common rail which distributes the fuel to the fuel injectors (Y76). The CDI control unit (N3/33) actuates the following fuel injectors rotational speed and load-dependent:
Cylinder 1 injector (Y76/9)
Cylinder 2 injector (Y76/10)
Cylinder 3 injector (Y76/11)
Cylinder 4 injector (Y76/12)
Differentiation is made between preinjection, main injection and post-injection. The system's maximum injection pressure is 1600 bar.
Air control system
Charge pressure control
Exhaust gas recirculation (EGR)
Exhaust system
Catalytic converter
Oxygen sensor heater
Diesel particulate filter
Starting, function | |||
Fuel supply, function | |||
Injection regulation, function | |||
Rpm control, function | |||
Alternator interface function | |||
Smooth running control, function | |||
Torque coordination, function | |||
Overrun mode fuel shutoff, function | |||
European OBD, function | |||
Engine start-stop function | With CODE MJ8 (ECO start/stop function) | ||
Charging, function | |||
Preheat, function | |||
Exhaust gas cleaning, function | |||
Overview of system components for common rail diesel injection (CDI) |