The DME control unit calculates the correct injection timing on the basis of the engine speed, air mass, throttle position, oxygen sensor voltage, engine and intake air temperature. A change in the fuel-air mixture is achieved on the basis of the opening duration of the fuel injectors. The battery or system voltage is also included in the calculation for the injection timing since the pickup and dropout times of the fuel injectors are extended as the voltage drops.
Each fuel injector is activated by its own output stage. This facilitates precise metering of the injection quantity and rapid response to load change.
Once the start procedure has been initiated, fuel is injected cylinder-selective 1 x per working cycle (2 crankshaft revolutions).
The injection timing (ti) is derived from the programmed basic start injection quantity and the correction variables from the input signals of the coolant and intake air temperature. Cylinder activation is based on the reference mark generator signal (crankshaft signal generator).
The DME M5.2 features cylinder-individual fuel injection (CIFI). CIFI involves the individual activation of each cylinder. The system ensures that fuel injection of each cylinder is completed before the inlet valve opens. An optimum fuel-air mixture and thus improved combustion with low fuel consumption is achieved in this way.
Injection of each cylinder can be deactivated individually if a fault occurs in the ignition or injection system. These faults are then also stored in the defect code memory.