ME-SFI Deceleration Fuel Shutoff Function

ME-SFI Deceleration Fuel Shutoff Function




Shown on Engine 119
B11/4 Coolant temperature sensor
B37 Accelerator pedal sensor
L5 Crankshaft position sensor
M16/1 Electronic accelerator (EA)/ cruise control (CC)/ idle speed control (ISC) actuator
N3/10 ME control unit
S40 CC [TPM] switch
Y62 Injectors (LH-SFI, HFM-SFI, PEC [LH, HFM, PMS])

Task
- Improve exhaust characteristics in the overrun
- Increase the braking effect of the engine in the overrun
- Reducing fuel consumption.

Function
In the deceleration mode the ME-SFI control unit switches off the fuel injectors if, for example, in the case of engine 119:
- Coolant temperature >50 °C
- Engine speed >1350 rpm
- Throttle valve closed (recognition through throttle valve actual value potentiometer)
- Cruise control "OFF"

The fuel injectors are switched on again if e.g. on engine 119:
- Engine speed <1100 rpm
- Throttle valve opened (recognition through throttle valve actual value potentiometer)
- Cruise control "ON"

The ignition timing point is briefly retarded when fuel injection re-commences after deceleration fuel shutoff in order to prevent a sudden increase in torque.

After the deceleration mode, the mixture is briefly enriched in order to eliminate the enriched oxygen in the three way catalytic converters resulting from the deceleration mode. This ensures that an optimal conversion rate is more rapidly achieved.

Note: Engine speed and coolant temperature differ depending on engine and transmission version.