Start quantity control, basic function

GF07.08-P-1052A

Start quantity control, basic function

09.09.2020

Engine

139, 176, 177, 254, 256, 260, 264, 279, 282

Overview

This document contains information on:

 General

 Function requirements

 Function

General

To achieve stable and smooth engine running, the fuel/air mixture is enriched via the combustion engine control unit.

The following enrichment phases are decided from:

 Cold start

 Post-start phase

 Warming-up phase

Function requirements

 Engine management ON (circuit 87M)

 Engine in operation

Function

Cold start enrichment:

In order to facilitate the engine starting procedure, an additional quantity of fuel is injected during the starting procedure. To this end, the combustion engine control unit calculates the required injection duration of the fuel injectors for the starting mixture enrichment. The higher the coolant temperature, the shorter the injection duration calculated by the combustion engine control unit. In order to compensate for the reduced start quantity for a lower battery voltage, the combustion engine control unit extends the injection duration.

Post-start enrichment:

In order to ensure that the engine continues to run perfectly, the fuel condensing in the cold cylinder barrels is compensated for by the post-start enrichment. To do this, the combustion engine control unit calculates the injection duration of the fuel injectors and extends it.

Warm-up enrichment:

The quantity of fuel condensed in the still cold cylinder barrels is compensated for by the warm-up enrichment. The injection duration of the fuel injectors is extended through the combustion engine control unit.

To provide additional heating of the combustion chambers, exhaust gas recirculation is activated during the warm-up phase.

 The lambda control monitors the injection duration as soon as this is enabled.

	Function schematics
	Function schematic for start quantity control	Engine 256 in model 223	PE07.70-P-2500-97E
		Engine 176, 177 in model 223	PE07.70-P-2500-97F
		Engine 279 in model 223	PE07.70-P-2500-97H
	Function schematic for start quantity control	Engine 260 in model 118, 177, 247 Engine 264 in model 167	PE07.70-P-2500A
		Engine 282 in model 118, 177, 247	PE07.70-P-2500B
		Engine 176, 177 in model 167	PE07.70-P-2500C
		Engine 139 in model 118, 177	PE07.70-P-2500D
	Control units
	Combustion engine control unit, basic function	Engine 139, 176, 177, 254, 256, 260, 264, 279, 282	GF07.08-P-9890A
	Components
	Fuel injectors, basic function	Engine 139, 176, 177, 254, 256, 260, 264, 279, 282	GF07.03-P-2000A