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

GF07.61-P-4022KE ME-SFI Lambda Control, Function
- up to model year 08

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 sensor upstream of TWC reacts to the oxygen share in the exhaust and transmits a corresponding voltage signal to the 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 an O2 sensor 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 sensor upstream of TWC
^ Engine idling or partial-load range
^ Deceleration fuel shutoff not active.

Component Identification:

Example:
Assuming a leaner fuel-air mixture is produced. This has the consequences that the O sensor voltage drops and the 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 control unit.