ME-SFI overrun fuel shutoff, function - GF07.61-P-4019G

ENGINE 273 in MODEL 463.202/222/236/237 up to 31.5.12 as of model year 2009/YoM 08

Fig 1: Identifying ME-SFI Overrun Fuel Shutoff Function Chart

Courtesy of MERCEDES-BENZ USA

Function requirements for deceleration fuel shutoff for the ME-SFI gasoline injection and ignition system (engine electronics) (ME), general points

Circuit 87M ON (engine control ON)
Engine running
Vehicle rolling
Accelerator not operated
Selector lever position "D" or "R"
Vehicle not in cruise control function
Not too high an exhaust temperature

ME-SFI deceleration fuel shutoff, general points

Deceleration fuel shutoff in deceleration mode of the engine has the following tasks:

Increasing the braking effect of the engine
Reducing fuel consumption
Improving exhaust characteristics

The ME-SFI [ME] control unit performs a deceleration fuel shutoff according to the following sensors and signals:

Coolant temperature sensor
Accelerator pedal sensor, accelerator pedal position
Crankshaft Hall sensor, engine speed
Electric controller unit (VGS), stage via the drive train CAN

ME-SFI deceleration fuel shutoff, function sequence

In deceleration mode, the ME-SFI [ME] control unit shuts off the fuel injection valves (Y62) according to coolant temperature, engaged gear and engine speed, if the accelerator pedal is not actuated.

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

The ME-SFI [ME] control unit also adjusts the valve overlap to its minimum value using the LH and RH intake camshaft solenoids and the LH and RH exhaust camshaft solenoids. This ensures that an optimal conversion rate of the catalytic converters is more rapidly achieved.

After deceleration fuel shutoff, the ME-SFI [ME] control unit enriches the fuel-air mixture by briefly extending the injection time, in order to protect the catalytic converters from enriched oxygen.

In order to prevent a sudden rise in torque when combustion is restarted after a deceleration fuel shutoff, the ME-SFI [ME] control unit briefly shifts the ignition angles of the ignition coils towards "retard".

Deceleration fuel shutoff is disabled when exhaust temperatures are too high, since the high oxygen content occurring in the exhaust during a deceleration fuel shutoff could cause increased oxidation of carbon monoxide and hydrocarbon (afterburning). The heat so generated can overheat the catalytic converters.

	Component description for ME-SFI [ME] control unit	N3/10	GF07.61-P-6000G
	Component description for fully integrated transmission control unit	Y3/8n4	GF27.60-P-5165GGA