Deceleration fuel shutoff, function - GF07.10-P-1014OM

ENGINE 651.9 in MODEL 204.0/2/3/9, 207.3/4, 212 (except 212.098/298), 218 

Function requirements for deceleration fuel shutoff, general points 

• Circuit 87M ON (engine timing ON)
• Engine running
• Vehicle rolling
• Accelerator not operated
• Selector lever position "D" or "R"
• Vehicle not in cruise control or DISTRONIC PLUS mode (vehicles with DISTRONIC PLUS)

Deceleration fuel shutoff, general 

Deceleration fuel shutoff causes the drive wheels to transmit a braking torque to the engine via the transmission. In this way the braking effect of the engine is increased.

The CDI control unit (N3/9) performs a deceleration fuel shutoff as specified by the following sensors and signals:

• Crankshaft position sensor (L5) (except code (B03) ECO start/stop function), engine rpm
• Coolant temperature sensor (B11/4) (model 204, 207, 212), coolant temperature sensor (B11/4) (model 218)
• Accelerator pedal sensor (B37), accelerator pedal position
• Crankshaft Hall sensor (B70) (with code (B03) ECO start/stop function), engine speed
• Intake port shutoff Hall sensor (B96) (model 204.9 as of 1.6.13 and code (494) USA version)
• Electronic transmission control control unit (N15/3) (with code (423) 5-speed (NAG) A/T), gear range via the drive train CAN (CAN C)
• Fully integrated transmission control controller unit (Y3/8) (with code (427) 7-speed A/T), gear range via drive train CAN

Deceleration fuel shutoff, function 

If the accelerator pedal is not actuated (zero quantity delivery), deceleration mode is triggered. The CDI control unit switches off the fuel injectors (Y76) in deceleration mode dependent on the coolant temperature, the engaged gear and at an engine speed >1600 rpm. The CDI control unit also lowers the fuel pressure in the rail through the quantity control valve (Y94) and the pressure regulating valve (Y74). If the accelerator pedal is depressed again or the engine speed falls below 1600 rpm, the CDI control unit re-actuates the fuel injectors and increases the fuel pressure in the rail via the quantity control valve and the pressure regulating valve.

As of 06/10 the engine 651.9 is a regulated engine oil pump. The engine oil pump valve (Y130) is actuated according to the operating condition by the CDI control unit so that the engine oil pump only delivers the required quantity of engine oil which leads to a reduction of fuel consumption.