GF07.61-P-4022AMG ME-SFI Lambda Control, Function

GF07.61-P-4022AMG ME-SFI Lambda Control, Function







The mixture composition is controlled within the narrowest possible limits around (Lambda)= 1 in order to achieve a high conversion of exhaust gases (exhaust gas conversion) in 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 (Lambda) =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 (Lambda) 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.














Example:
Assuming a leaner fuel-air mixture is produced. This has the following consequence, that the O sensor voltage drops and the ME-SFI [ME] 2 control unit compensates for this lean drift through a matching enrichment.

This makes it possible to achieve a fuel-air mixture of approximately (Lambda)=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.