ME-SFI lambda control, function - GF07.61-P-4022M
ENGINE 275.950 in MODEL 215, 220
ENGINE 275.951 in MODEL 230 up to Model Year 8
ENGINE 275.953 in MODEL 216, 221 up to Model Year 8
ENGINE 275.954 in MODEL 230 up to Model Year 8
ENGINE 275.980 in MODEL 215, 220
ENGINE 275.981 in MODEL 230 up to Model Year 8
ENGINE 275.982 in MODEL 216, 221 up to Model Year 8
ENGINE 285.950 in MODEL 240
ENGINE 285.980 in MODEL 240
The mixture composition is controlled within the narrowest possible limits around λ = 1 in order to achieve a high conversion of the exhaust gases (exhaust gas conversion) in the catalytic converters.
The O2 sensors upstream of TWC react to the oxygen share in the exhaust and transmits a corresponding voltage signal to the ME-SFI [ME] control unit. Consequently, the mixture composition is modified by control of the injection quantity, so that λ=1 is obtained. This process is repeated constantly (control loop).
The ME-SFI [ME] control unit alters the mixture composition with a time delay in order to prevent any risk of jerking.
Control of the air/fuel ratio is much faster by using a wideband oxygen sensor (continuous signal of λ 0.7 to 4.0) as O2 sensors upstream of TWC.
The function of the lambda control (closed-loop operation) is dependent upon:
- Coolant temperature at start (dependent on the particular operating condition)
- Operating temperature of the O2 sensors upstream of TWC
- Engine idling or partial-load range
- Deceleration fuel shutoff not active.
Exhaust gas conversion in the three way catalytic converter
Example:
Assuming a leaner fuel-air mixture is produced. This has the consequences that the O2 sensor voltage drops and the ME control unit compensates for this lean drift through a matching enrichment.
This makes it possible to achieve a fuel-air mixture of approximately λ = 1.
The readout of the lambda control factor with the DAS alters in the direction +25%.
The more the lambda control factor moves in the direction +25%, the leaner is the fuel-air mixture and the greater is the enrichment of the mixture on the part of the ME control unit.
| ME-SFI [ME] control unit, location/task/design/function | GF07.61-P-5000M | ||
| O2 sensors, location/task/design/function | GF07.04-P-4103M | ||
| Coolant temperature sensor, location/task/design/function | GF07.04-P-5026M | ||
| Pressure sensor downstream of throttle valve actuator, location/task/function | GF07.04-P-5049M | ||
| Accelerator pedal sensor, location/task/design/function | GF30.20-P-4010M | ||
| Fuel injection valve, location/task/design/function | GF07.03-P-5004M | ||
| Three-way catalytic converter, location/task/design/function | GF49.10-P-3002M | ||
| Charge air temperature sensor, location/task/function | GF07.04-P-5038M |