GF07.61-P-4022F | ME-SFI lambda control, function | 9.1.09 |
ENGINES 104.941 /943 /944 /991 /994 as of /96
ENGINES 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 1997 Japan version
ENGINES 111.921 /942 as of 1.9.98,
111.943,
111.944 as of 1.8.96, 111.946 as of 1.6.98, 111.947 /952 /956 /957 /958 /973, 111.975 as of 1.8.96, 111.982 /983
ENGINES 111.951 /955 up to model year 2008/AEJ 07
ENGINES 111.945
in model 208. as of 1.6.98,
202.020 /080 as of 1.9.98
ENGINES 111.974
with CODE (494) USA version
with CODE (807) model year 1997
with CODE (808) model year 1998
ENGINES 112.910 /911 /912 /913 /914 /916 /917 /920 /921 /922 /923 /940 /941 /942 /943 /944 /947 /949 /953 /954 /955 /970 /972 /975
ENGINES 112.946 /973 up to model year 2008/AEJ 07
ENGINES 113.940 /941 /942 /943 /948 /960 /961 /965 /966 /967 /968 /969
ENGINES 113.963 up to model year 2008/AEJ 07
ENGINES 119.980 /981 /982 /985
ENGINES 120.982/ 983
ENGINES 137.970
P07.61-0396-06
Shown on engine 119
158 Three-way catalytic converter
B2/5 Hot film mass air flow sensor
B11/4 Coolant temperature sensor
B37 Accelerator pedal sensor
G3/3 Left O2 sensor upstream of catalytic converter
G3/4 Right O2 sensor upstream of catalytic converter
N3/10 ME-SFI [ME] control unit
Y62 Fuel injection valves
The mixture composition is maintained within the narrowest possible limits around λ = 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 [ME] control unit for fuel injection, which thereupon alters the mixture composition in such a way as to produce a mixture composition of λ = 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 [ME] 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° C
- O2 sensors have reached operating temperature
- Idle speed/partial load
- Deceleration fuel shutoff inactive.
ME-SFI [ME] control unit: fuel,
air mixture "ENRICH"
P49.10-0306-01
Injection time extended
Air/fuel mixture
mixture
Oxygen concentration in exhaust
Small
ME-SFI [ME] control unit: air/
fuel mixture
"ENLEAN"
O2 sensor voltage,
voltage jump
at λ = 1
O2 sensor voltage rises
Oxygen concentration in exhaust
high
Air/fuel mixture
"LEAN"
Injection time reduced
O2 sensor voltage drops
O2 sensor voltage,
voltage jump
at λ = 1
A Exhaust conversion rate
B Control range around
λ = 1 (catalytic converter window)
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 [ME] control unit compensates for this lean drift by enriching the mixture accordingly.
This makes it possible to achieve an air/fuel composition of approximately λ = 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-SFI [ME] control unit.
- 25% 0 + 25%
Lambda control factor (HHT/STAR DIAGNOSIS)
Reaction of ME-SFI [ME] control unit
O2 sensor voltage
Air/fuel mixture
"RICH" tendency "LEAN"
approx. 0.9 V tendency approx. 0.1 V
"ENLEAN" tendency "ENRICH"
Engine 112.946 with code 929 Flexible Fuel Vehicle (FFV)
After each fueling the Ethanol portion is determined by means of the O2sensor voltage upstream catalytic converter 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 fuelingλ =1 is achieved again.
ME-SFI [ME] control unit, location/task/design/function | Other than engine 111 EVO | ||
Engine 111 EVO | |||
O2 sensors, location/task/design/function | |||
O2 sensor heater, function | |||
Coolant temperature sensor, location/task/design/function | Engine 119, 120 | ||
Engines 104, 111 | |||
Engine 112, 113, 137 | |||
Self-adjustment of mixture formation, function | |||
Hot film mass air flow sensor, location/task/design/function | Engine 119, 120 (round connector) | ||
Engines 104, 112, 113, 137 Engine 111 (except engine 111 EVO) | |||
Engine 111 EVO | |||
Pedal value sensor, location/task/design/function | |||
Fuel injection valve, location/task/design/function | |||
ME-SFI two-sensor control, function | Engine 104, 111, 112, 113, 119, 120, 137 with EURO3/4 (code 925/926 or as standard) and | ||
Three-way catalytic converter, location/task/design/function | |||
ME-SFI Flexible Fuel Vehicle (FFV), function | Code 929 Flexible Fuel Vehicle (FFV), engine 112.946 |
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