Overrun mode fuel shutoff, basic function

GF07.10-P-1049A

Overrun mode fuel shutoff, basic function

09.09.2020

Engine

all (CAR)

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

 Transmission position N engaged (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, selector lever 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.

	Function schematics
	Function schematic for overrun mode fuel shutoff	Engine 176, 177 in model 167	PE07.10-P-2508-97B
		Engine 260, 282, 608 in model 118, 177, 247Engine 264 in model 167	PE07.10-P-2508-97C
		Engine 654 in model 118, 177, 247Engine 654 in model 213, 238, 257 as of model year 2021Engine 654, 656 in model 167	PE07.10-P-2508-97D
		Engine 254, 264 in model 213, 238, 257 as of model year 2021Engine 256 in model 167Engine 256 in model 213, 238 as of model year 2021	PE07.10-P-2508-97E
		Engine 139 in model 118, 177	PE07.10-P-2508-97F
		Engine 256 in model 223	PE07.10-P-2508-97G
		Engine 176, 177 in model 223	PE07.10-P-2508-97H
		Engine 279 in model 223	PE07.10-P-2508-97I
	Control units
	Combustion engine control unit, basic function	Engine all (CAR)	GF07.08-P-9890A