Overrun Mode Fuel Shutoff, Basic Function - GF07.10-D-1049A

Engine All (Light transporter) 

Overview 

This document contains information on:

• General 
• Function requirements 
• Function 

General 

In order to reduce fuel consumption, increase the braking effect of the combustion engine and improve the exhaust characteristics, the overrun mode fuel shutoff interrupts the fuel supply to the combustion engine under certain driving conditions. The combustion produces no further output so that the vehicle is only rolling.

Function requirements 

• Engine management ON (circuit 87M)
• Engine in operation
• Accelerator not operated
• Transmission position "D" or "R" engaged (automatic transmission)
• Transmission position "N" (when the vehicle is at a standstill or rolling)
• Speed control or distance control not active
• Not too high an exhaust temperatures

Function 

If the accelerator pedal is not operated, the overrun mode fuel shutoff automatically comes into operation.

The combustion engine control unit no longer actuates the fuel injectors, depending on the input signals of the coolant temperature, transmission position and engine speed. With a diesel engine, the combustion engine control unit reduces the fuel quantity and accordingly the fuel pressure in the fuel distributor, also via the quantity control valve.

When the accelerator pedal is operated, the combustion engine control unit actuates the fuel injectors again. With a diesel engine, the combustion engine control unit also increases the fuel quantity and the fuel pressure in the fuel distributor via the quantity control valve.