Start Quantity Control, Basic Function - GF07.08-D-1052A

Engine 274 

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 do this, the combustion engine control unit calculates the required injection duration of the fuel injectors for 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 by 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.