ME-SFI lambda control, function - GF07.61-P-4022M
ENGINE 275.950 in MODEL 215, 220
ENGINE 275.951 in MODEL 230
ENGINE 275.953 in MODEL 216, 221
ENGINE 275.954 in MODEL 230
ENGINE 275.980 in MODEL 215, 220
ENGINE 275.981 in MODEL 230
ENGINE 275.982 in MODEL 216, 221
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 |