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Home >> Mercedes Benz >> 2007 >> CL550 >> Repair and Diagnosis >> Engine Performance >> Tune-Up >> Mixture Formation -- Cl550 -- 216 Chassis >> Basic Knowledge >> ME-SFI warming-up control, function - GF07.61-P-3022V

ME-SFI warming-up control, function - GF07.61-P-3022V

ENGINE 273.961 in MODEL 216, 221 up to Model Year 8 

Shown on ENGINE 272 

Fig 1: Warming-Up Control Function Diagram
G07634029Courtesy of MERCEDES-BENZ USA
Fig 2: Enrichment Rate And Time Graph
G07634030Courtesy of MERCEDES-BENZ USA

After start and post-start enrichment the fuel-air mixture is further enriched by the warming-up control as part of the fuel-air mixture precipitates on the parts of the engine which are still cold.

An additional quantity of fuel is added to the engine by the ME-SFI [ME] control unit in line with the performance map.

As soon as it is enabled, the Lambda control monitors the enrichment rate.

At close to idle operation, the enrichment rate is mainly dependent on the coolant temperature at start. At partial load, the air mass is decisive.

The camshaft position determines the exhaust gas recirculation rate via the duration of the valve overlap. As the hot exhaust gases warm up the combustion chamber, the fuel vaporization changes and the enrichment rate must be tuned to match it.

The coolant is controlled by the three-disk thermostat in such a way that it is warmed as quickly as possible.

During warm-up, the ignition angles are determined from a particular performance characteristic.

The warming-up enrichment is dependent on:

Component description for the ME-SFI [ME] control unit   GF07.61-P-6000V 
Component description for the coolant temperature sensor   GF07.04-P-6040V 
Component description for the camshaft Hall sensor   GF07.04-P-6020V 
Component description for the crankshaft Hall sensor   GF07.04-P-6220V 
Component description for the hot film MAF sensor   GF07.07-P-6000V 
Component description for the accelerator pedal sensor   GF30.20-P-2010V
Component description for the throttle valve actuator   GF30.20-P-2020V
Component description for an O2 sensor Component description for O2 sensors upstream of TWC GF07.04-P-6100V
O2 sensors downstream of TWC GF07.04-P-6100VA
Component description for the camshaft solenoid   GF05.20-P-2100V
Component description for the fuel injection valves   GF07.03-P-6010V 
Component description for the valve three-disk thermostat   GF20.10-P-3160V