ME-SFI deceleration fuel shutoff, function - GF07.61-P-4019V

ENGINE 272.920 in MODEL 203 up to Model Year 8

ENGINE 272.922 in MODEL 211

ENGINE 272.940 in MODEL 203 up to Model Year 8

ENGINE 272.941 in MODEL 203 up to Model Year 8

ENGINE 272.942 in MODEL 171 up to Model Year 8

ENGINE 272.943 in MODEL 211, 219

ENGINE 272.944 in MODEL 211

ENGINE 272.945 in MODEL 251 up to Model Year 8

ENGINE 272.946 in MODEL 221 up to Model Year 8

ENGINE 272.960 in MODEL 203 up to Model Year 8

ENGINE 272.963 in MODEL 171 up to Model Year 8

ENGINE 272.964 in MODEL 211, 219

ENGINE 272.965 in MODEL 221 up to Model Year 8

ENGINE 272.966 in MODEL 230 up to Model Year 8

ENGINE 272.967 in MODEL 164, 251 up to Model Year 8

ENGINE 272.970 in MODEL 203 up to Model Year 8

ENGINE 272.972 in MODEL 211

ENGINE 272.975 in MODEL 221 up to Model Year 8

ENGINE 273.922 in MODEL 221 up to Model Year 8

ENGINE 273.923 in MODEL 164 up to Model Year 8

ENGINE 273.924 in MODEL 221 up to Model Year 8

ENGINE 273.960 in MODEL 211, 219

ENGINE 273.961 in MODEL 216, 221 up to Model Year 8

ENGINE 273.962 in MODEL 211

ENGINE 273.963 in MODEL 164, 251 up to Model Year 8

ENGINE 273.965 in MODEL 230 up to Model Year 8

ENGINE 273.967 in MODEL 209

ENGINE 273.968 in MODEL 221 up to Model Year 8

ENGINE 272.940 in MODEL 209

ENGINE 272.960 in MODEL 209

Shown on ENGINE 272.963

Fig 1: ME-SFI Deceleration Fuel Shutoff Function Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Deceleration fuel shutoff has the following tasks:

Increasing the braking power of the engine in the deceleration mode
Reducing fuel consumption
Improving exhaust emissions in the deceleration mode.

In the overrun mode, the ME control unit switches off the fuel injection valves depending on the coolant temperature and the gear engaged, if the accelerator pedal is not operated (detected via the actual value signal from the accelerator pedal sensor).

The fuel injection valves are switched on again when the accelerator pedal is operated.

The deceleration fuel shutoff is suppressed at too high exhaust gas temperatures, because the high oxygen content in the exhaust during deceleration fuel shutoff can lead to an increased oxidation of carbon monoxide and hydrocarbon (afterburning). This can result in additional heat (thermal reaction) that can overheat the catalytic converters.

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. The valve overlap is also set to its minimum value by the camshaft adjustment. This ensures that an optimal conversion rate is more rapidly achieved.

In order to prevent a sudden torque rise when combustion is reestablished after deceleration fuel shutoff, the ignition timing is briefly adjusted towards "retarded".

The engine speed when combustion cuts in is dependent on the coolant temperature, the engine and transmission versions and with automatic transmission, dependent on the drive position selected (via the CAN from the transmission control unit).

Deceleration fuel shutoff is blocked under the following conditions:

with automatic transmission in selector lever position P or N
with manual transmission with clutch pedal depressed.

Component description for the ME-SFI [ME] control unit	GF07.61-P-6000V
Component description for the accelerator pedal sensor	GF30.20-P-2010V
Component description for the crankshaft Hall sensor	GF07.04-P-6220V
Component description for the coolant temperature sensor	GF07.04-P-6040V
Component description for the fuel injection valves	GF07.03-P-6010V