Engine Control Module: Description and Operation

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

Component Identification:

The mixture composition is controlled within the narrowest possible limits around lambda= 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 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.

Component Identification:

Example:
produced. This has the consequences that the O sensor voltage drops and the ME control 2 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 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.