ME-SFI lambda control, function - GF07.61-P-4022AMG
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
The mixture composition is controlled within the narrowest possible limits around λ = 1 in order to achieve a high conversion of exhaust gases (exhaust gas conversion) in catalytic converters.
The O 2 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 O 2 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 O 2 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 following consequence, that the O2 sensor voltage drops and the ME-SFI [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 reading of the lambda control factor with the STAR DIAGNOSIS moves towards +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-SFI [ME] control unit.
| Component description for fuel injection valves | Y62y1-Y62y8 | GF07.03-P-6010AMG | |
| Component description for the coolant temperature sensor | B11/4 | GF07.04-P-6040AMG | |
| Component description for O 2 sensors | G3/3, G3/4 | O2 sensors upstream of TWC | GF07.04-P-6100AMG |
| G3/5, G3/6 | O2 sensors downstream of TWC | GF07.04-P-6100AMH | |
| Component description for the crankshaft Hall sensor | B70 | GF07.04-P-6220AMG | |
| Component description for the hot film mass air flow sensor | B2/6, B2/7 | GF07.07-P-6000AMG | |
| Component description for the ME-SFI [ME] control unit | N3/10 | GF07.61-P-6000AMG | |
| Component description for the accelerator pedal sensor | B37 | GF30.20-P-2010AMG | |
| Component description for the three-way catalytic converter | 157, 158 | GF49.10-P-2010AMG |