C 350 (204.056) V6-3.5L (272.961) (2008)
Engine Control Module: Description and Operation
GF07.10-P-1029CY Self-Adjustment of Mixture Formation, Function
GF07.10-P-1029CY Self-adjustment Of Mixture Formation, Function
- up to model year 08
Component Identification
For regulated catalytic converters the lambda control determines the injection time so exactly that a certain fuel-air ratio (lambda) is maintained under all
operating conditions.
The following faults can occur:
^
Unmetered air
^
Wear or coking of the injection valves (Y62)
^
Damaged pressure sensor (B28)
^
Transition resistance in the hot film mass air flow sensor (B2/5)
^
Defective purge control valve (Y58/1)
^
Harmful fuel pressure regulator
^
Wear to the engine (e.g. valve leakage)
If a fault occurs, the ME-SFI [ME] control unit (N3/10) automatically makes a correction in the mixture formation. Here the lambda performance map is
shifted within certain limits in such a way that the lambda control is not at the upper or lower regulator stop.
If the mixture composition constantly drifts out of the middle control range (e.g. 0±10%), the ME-SFI [ME] control unit shifts the lambda map under
certain operating conditions sufficiently far until a lambda control factor of approx. 0% (g) is again achieved.
Self-adjustment ensures that the mixture composition in the control mode (e.g. warming-up phase) is neither too rich nor too lean. This also prevents the
lambda control from moving up to the control limit at high altitudes.
Example:
As the result of a lean fuel/air mixture the readout of the lambda control factor changes to 18% (e). Under certain operating conditions the lambda
performance map is shifted (arrow) by the ME-SFI [ME] control unit.
This shifting of the lambda map is the self-adaptation of the mixture formation to the existing fuel-air mixture.
After this self-adjustment the lambda control factor is again in the central control range (g).
Self-adjustment of the mixture formation can be carried out in the following operating states:
^
Idle speed
^
Lower part load
^
Upper part load