ME-SFI starting, function - GF07.61-P-2003AMG

ENGINE 156.980 in MODEL 164, 251 up to Model Year 8 

ENGINE 156.982 in MODEL 209 

ENGINE 156.983 in MODEL 211, 219 

ENGINE 156.984 in MODEL 216, 221 up to Model Year 8 

Fig 1: Identifying ME-SFI Starting CAN Communication Diagram

Courtesy of MERCEDES-BENZ USA

Functions when starting: 

• Engine control voltage supply
• Fuel supply
• Start quantity control (injection system)
• Ignition system
• Starter control
• Engine speed signal
• Synchronization of fuel injection and firing order

Enrichment of fuel in engine oil 

For a cold start, fuel condensing on the still cold cylinder liner can enrich the fuel in the engine oil. Once the engine oil becomes hot, the fuel evaporates the fuel again and this is led again via the crankcase ventilation system to the engine for combustion. The mixture deviation (a rich mixture) in neutral can be up to 30% and is corrected by the lambda control. Mixture adaptation saves this correction as a long-term effect. This means that a subsequent start could fail if the start mixture is too lean, although no exhalation of fuel takes place. To prevent this, the ME-SFI [ME] control unit constantly calculates the fuel quantity in the engine oil. To do this, the number of starts, the start temperature and the subsequent operating duration are evaluated.