S07.10-0007-79
Block diagram |
A1/1 | Instrument cluster (KI) control unit | N50 | Fuse and relay module control unit (SRM) | |
A16 | Knock sensor | N50k2 | Circuit 15 relay | |
B2/8 | Hot film mass air flow sensor | N93 | Central gateway (CGW) | |
B6/15 | Intake camshaft position sensor | S2 | Ignition lock switch | |
B6/16 | Exhaust camshaft position sensor | T1 | Ignition coils | |
B11/17 | Coolant temperature sensor | Y49/10 | Intake camshaft solenoid | |
B28/15 | Intake manifold pressure sensor | Y49/11 | Exhaust camshaft solenoid | |
B37/4 | Accelerator pedal module | Y62 | Fuel injectors | |
B70/2 | Crankshaft Hall sensor | CAN HMI | User interface CAN | |
G1 | On-board electrical system battery | CAN V | Vehicle CAN | |
G3/2 | Oxygen sensor upstream of catalytic converter | A | Mercedes-Benz | |
M16/6 | Throttle valve actuator | B | Nissan | |
N3/34 | ME-SFI [ME] control unit | C | Default | |
N10/1 | Signal acquisition and actuation module (SAM) control unit | D | Optional |
Function requirements for starting, the post-start phase and warm-up enrichment, general points
Circuit 87 ON (engine management ON)
Engine running.
Start phase, post-start phase and warm-up enrichment, general
In order to achieve stable and smooth engine running for a cold start, the fuel/air mixture is enriched by the ME-SFI control unit.
Function sequence for start phase, post-start phase and warm-up enrichment
The function sequence is divided into the following subfunctions:
Function sequence for starting mixture enrichment
Function sequence for post-start enrichment
Function sequence for warm-up enrichment
Function sequence for starting mixture enrichment
To allow easier starting when the engine is cold, more fuel has to be injected during the starting procedure.
The ME-SFI control unit calculates the injection duration for starting mixture enrichment on the basis of the signals from the following sensors:
Coolant temperature sensor, coolant temperature
Crankshaft Hall sensor, engine speed
Upon receiving the "circuit 50 signal" from the electronic ignition lock switch, the ME-SFI control unit extends the injection period of the fuel injectors.
Starting mixture enrichment remains active until the engine speed dependent on the particular coolant temperature is exceeded.
The higher the coolant temperature, the shorter the injection period calculated by the ME-SFI [ME] control unit.
No engine start is possible below an on-board electrical system voltage of approx. 7 V.
Function sequence for post-start enrichment
After cold start, the fuel-air mixture is further enriched.
Enleanment due to the fuel condensating on the still cold cylinder surfaces is compensated by the post-start enrichment.
The ME-SFI control unit calculates the injection duration of the fuel injectors for the post-start enrichment on the basis of the coolant temperature at start and the number of combustion cycles since the start.
An additional fuel quantity is added to the engine by the ME-SFI [ME] control unit in line with the characteristics map.
Function sequence for warm-up enrichment
After start and post-start enrichment, the fuel-air mixture is further enriched via the warm-up enrichment in order to ensure rapid warm-up.
The ME-SFI control unit calculates the injection duration of the fuel injectors for warm-up enrichment on the basis of the signals from the following sensors:
Intake camshaft position sensor, intake camshaft position
Exhaust camshaft position sensor, exhaust camshaft position
Coolant temperature sensor, coolant temperature
Intake manifold pressure sensor, engine load
Crankshaft Hall sensor, engine speed
An additional quantity of fuel is metered to the engine in line with the performance map. To do this, the ME-SFI control unit extends the injection period for the fuel injectors. It will also take into account any correction programming that may have been made.
The ignition angles of the ignition coils during warm-up are determined according to a specific characteristics map.
Via the intake camshaft actuator solenoid and the exhaust camshaft actuator solenoid, the ME-SFI control unit determines the internal exhaust gas recirculation based on the valve overlap. As the hot exhaust gases heat up the combustion chambers, fuel evaporation is increased and fuel enrichment can be reduced.
In the near idling range, the injection duration depends primarily on the coolant temperature; under partial and full load, the load requirement is the decisive factor.
Once enabled, the lambda control monitors the injection period.