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

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


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.

Oxygen sensors on the left and right upstream of the TWC (G3/3, G3/4) react to the oxygen portion in exhaust gas and send appropriate voltage signals to the ME-SFI [ME] control unit (N3/10). 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) than an oxygen sensor upstream of TWC.

The function of the lambda control (closed-loop operation) is dependent upon:
^ Coolant temperature >-10 °C
^ Blocking time after starting expired
^ Operating temperature of the oxygen sensors upstream of catalytic converter
^ 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 following consequence, that the The oxygen sensor voltage drops and the ME-SFI [ME] control unit compensates for this lean drift by making a matching enrichment. This makes it possible to achieve a fuel-air mixture of approximately lambda= 1.
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 enrichment of the mixture on the part of the ME-SFI [ME] control unit.