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

GF07.61-P-4022MOR ME-SFI Lambda Control, Function
- refinement package
- as of model year 09


Function requirements for lambda regulation, general points
^ Circuit 87M ON (engine control ON)
^ Engine running
^ Coolant temperature >52 °C
^ Operating temperature reached in LH and RH O2 sensors upstream of catalytic converter (G3/3, G3/4)
^ Engine idling or partial-load range
^ Deceleration fuel shutoff not active.

Lambda regulation, general points
The mixture composition is controlled within the narrowest limits around lambda= 1 in order to achieve high conversion of the exhaust gases (exhaust gas conversion) in the catalytic converters. For this purpose, the ME-SFI [ME] control unit (N3/10) reads the following sensors:
- Coolant temperature sensor ()B11/4
- Charge air temperature sensor (B17/8) and pressure sensor downstream of throttle valve actuator (B28/7), engine load
- LH and RH O2 sensors upstream of catalytic converter, oxygen sensor signals

Lambda regulation function sequence
The O2 sensors upstream of the catalytic converter react to the oxygen content in the exhaust and send the corresponding voltage signals to the ME-SFI [ME] control unit. This then regulates the mixture composition by adjusting the injection time of the fuel injection valves (Y62) so that lambda=1 is reached. 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.

Component Identification:

Example:
Assuming a leaner fuel-air mixture is produced. As a result, the oxygen sensor voltage drops and the ME-SFI [ME] control unit compensates for the leaner mixture by enriching it accordingly (extending the injection time).
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-SFI [ME] control unit.