Deceleration fuel shutoff function - GF07.10-P-1014MI

ENGINE 272.9 (except 272.98) in MODEL 204.0 /2 as of model year 2009/YoM 08

ENGINE 272.9 (except 272.98) in MODEL 204.9, 207.3 /4, 212.0 /2

ENGINE 273.9 in MODEL 207.3 /4, 212.0 /2

Function requirements for deceleration fuel shutoff, general points

Circuit 87M ON (engine control ON)
Engine running
Vehicle rolling
Accelerator not operated
Selector lever position "D" or "R" (for automatic transmission)
Vehicle not in cruise control or Distronic Plus mode (if Distronic PLUS installed)
Not too high an exhaust temperature

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 (N3/10) control unit performs a deceleration fuel shutoff according to the following sensors and signals:

Coolant temperature sensor (B11/4)
Accelerator pedal sensor (B37), accelerator pedal position
Crankshaft Hall sensor (B70), engine speed
Clutch pedal switch (S40/3) (for manual transmission)
Fully integrated transmission control controller unit (Y3/8), stage via the drive train CAN (CAN C) (for an automatic transmission)

Deceleration fuel shutoff function sequence

In deceleration mode, the ME-SFI control unit switches off the injection valves (Y62) depending on coolant temperature, selected gear and engine speed, if the accelerator pedal is not actuated. The injection valves are switched on again when the accelerator pedal is actuated.

If the clutch pedal is actuated for a manual transmission the deceleration fuel shutoff is broken off or suppressed.

The ME-SFI [ME] control unit also the valve overlap to its minimum value via the LH and RH intake camshaft solenoids (Y49/4, Y49/5) and the LH and RH exhaust camshaft solenoids (Y49/6, Y49/7). 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 of 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 control unit briefly shifts the ignition angles of the ignition coils (T1) 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 of the catalytic converters.

	Component description for ME-SFI [ME] control unit	N3/10 Engine 272	GF07.61-P-6000MI
	Component description for fully integrated transmission control unit	Y3/8n4 Model 204.0/2/9 for transmission 722.9	GF27.60-P-5165AHW