GF07.61-P-4022F ME-SFI Lambda Control, Function
GF07.61-P-4022F ME-SFI Lambda Control, Function
- 104.941/991/994 as of /96
- 104.995
- with CODE (494) USA version
- with CODE (807) Model year 1997
- with CODE (808) Model year 1998
- with CODE (498) as of Model Year 97 Japan version
- 111.973
- 111.975 as of 1.8.96
- 111.974
- with CODE (494) USA version
- with CODE (807) Model year 1997
- with CODE (808) Model year 1998
- 112.912/916/920/940/941/942/947/949/954/955/970/972
- 112.946 up to Model Year 08
- 113.940/941/942/943/948/960/961/965/966/967/968/969
- 119.980/981/982/985
- 120.982/983
- 137.970
The mixture composition is maintained within the narrowest possible limits around Lambda=1 in order to achieve a high conversion of the exhaust gases in the catalytic converter.
The O2 sensor reacts to the oxygen concentration in the exhaust and transmits the corresponding voltage signal to the ME-SFI control unit for fuel injection, which thereupon alters the mixture composition in such a way as to produce a mixture composition of Lambda=1 in all operating states when the lambda closed-loop control is active. This procedure is constantly repeated (control loop), with the cycle rate depending on engine load and speed. The ME-SFI control unit alters the mixture composition with a time delay in order to prevent any risk of jerking.
The lambda closed-loop control is operational in the following operating conditions (closed-loop control):
- Coolant temperature > 52 degrees C
- O2 sensors have reached operating temperature
- Idle speed/partial load
- Deceleration fuel shutoff inactive.
Example:
Assuming a leaner air/fuel mixture is produced.
The consequence of this is that the O2 sensor voltage tends to move in the direction of 0.1 V and the ME-SFI control unit compensates for this lean drift by enriching the mixture accordingly.
This makes it possible to achieve an air/fuel composition of approximately Lambda=1. The readout of the lambda control factor on the HHT 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.
(USA) Engine 112.946 with code 929 Flexible Fuel Vehicle (FFV)
After each fueling the Ethanol portion is determined by means of the O2 sensor voltage upstream TWC in the fuel tank. If for example Ethanol was refueled, the mixture is at first too lean (oxygen sensor voltage jumps back to 0 Volt). The lambda control reacts if the mixture to be enriched until after fueling Lambda=1 is achieved again.