GF07.61-P-0001M Motor Electronics (ME-SFI) Fuel Injection and Ignition System, Function

GF07.61-P-0001M Motor Electronics (ME-SFI) Fuel Injection And Ignition System, Function

The ME fuel injection and ignition system is a further development of the LH and DI and HFM systems, respectively.

The abbreviated designation ME 2.7.1 means:
M = Motronic (motor electronics)
E = Electronic accelerator pedal (electronic accelerator)
2.7.1 = Version (further design 2.7.2, 1.0, 2.0, 2.1, 2.7 or 2.8)

The following functions are combined in the ME-SFI control unit:
^ Ignition system
^ Injection system
^ Electronic accelerator/cruise control/idle speed control
^ Diagnosis/fault storage
^ Drive authorization system/immobilizer
^ Emission control system

Fuel injection system
The fuel is injected by electromagnetic fuel injectors. These are actuated sequentially by the ME-SFI control unit, in other words an injector is assigned to each cylinder which meters the quantity of fuel computed for the cylinder.

The main measurement for determining the fuel measure is the intake manifold pressure (load detection). It is detected by means of the pressure sensor downstream of throttle valve actuator (B28/7). A performance map dependent boost pressure control protects the engine against overload.

The ME control unit essentially analyzes the following information:
^ Coolant temperature
^ Engine speed and crankshaft position
^ Camshaft position
^ Throttle valve position
^ Charge air temperature
^ Accelerator pedal position
^ Vehicle speed (via CAN)
^ Knock identification
^ O2 sensor signals
^ Oil level, oil temperature and oil quality
^ Atmospheric pressure (in the ME control unit)
^ Air pressure downstream of air filter, right and left cylinder bank
^ Boost pressure (upstream of throttle valve actuator)
^ Intake manifold pressure (downstream of throttle valve actuator)

Idle speed control
The idle speed is controlled by the throttle valve actuator, which is operated by the ME control unit, by altering the position of the throttle valve.

Electronic accelerator
No mechanical link between accelerator pedal and throttle valve actuator. The accelerator pedal sensor detects the accelerator pedal input for the ME control unit.

Transmission shift delay
The shift points of the automatic transmission are delayed in line with temperature, vehicle speed and time in order to more rapidly heat up the catalytic converter to its operating temperature.

ECI ignition system
The ECI ignition system is an AC voltage ignition system with each one ignition module for the right and left cylinder bank and a common power pack. Two spark plugs are assigned to each cylinder.
The high voltage is distributed without use of moving parts, directly by the ignition coils to the spark plugs (rotorless high voltage distribution). The anti-knock control (AKC) function is integrated in the ME-SFI control unit. The knock identification is performed via four knock sensors.

CAN data bus
Depending on equipment and model the following control units are networked over the CAN:
^ ME control unit
^ EGS control unit
^ ESP, SPS [PML] and BAS control unit
^ SBC control unit (model 230, 240)
^ Electronic selector lever module control unit
^ AAC [KLA] control and operating unit
^ Restraint systems control unit
^ EIS [EZS] control unit
^ FBS control unit
^ DTR control unit
^ Steering column module
^ Instrument cluster
^ SAM control unit with fuse and relay module for the driver (model 240)
^ SAM control unit with fuse and relay module for the passenger (model 240)
^ Rear 2 SAM control unit with fuse and relay module (model 240)

Enabling of engine control
The engine can only be started in conjunction with a drive authorization system (FBS 3). The ME-SFI control unit is networked with the DAS via the CAN.