Self-adaptation of mixture formation function - GF07.61-P-3030F

ENGINE 104.941 /942 /943 /944 /945 /991 /992 /994 /995 

ENGINE 111.921 /942 /943 /944 /945 /946 /947 /951 /952 /955 /956 /957 /958 /960 /961 /970 /973 /974 /975 /982 /983 

ENGINE 112.910 /911 /912 /913 /914 /916 /917 /920 /921 /922 /923 /940 /941 /942 /943 /944 /946 /947 /949 /953 /954 /955 /973 /975 

ENGINE 113.940 /941 /942 /943 /948 /960 /961 /963 /965 /966 /967 /968 /969 

ENGINE 119.980 /981 /982 /985 

ENGINE 120.982/ 983 

ENGINE 137.970 

On vehicles with controlled catalytic converter the lambda control determines the injection time to such a degree of exactness that the fuel-air ratio λ=1 under all operating conditions.

If faults occur, the ME control unit 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 (d).

The following faults make a mixture adaptation necessary:

• Unmetered air
• Wear or carbon deposits on fuel injectors
• Transition resistance in the air flow meter
• Incorrect injection pressure (e.g. through plugged fuel filter or harmful diaphragm pressure regulator)
• Harmful purge control valve with high enrichment from the activated charcoal canister
• Wear to the engine (e.g. leaky valves)

If the mixture composition constantly drifts out of the middle control range (e.g. 0 ± 10 %), the ME control unit under certain operating conditions shifts the lambda performance map sufficiently far until a lambda control factor of approx. 0 % (g) is again achieved.

Self-adaptation ensures that the mixture composition in the open-loop mode (e.g. warming-up phase) is neither too rich nor too lean. This also prevents the lambda control moving up to the control stop at high altitudes.

Example:

As the result of a leaner fuel/air mixture the readout of the lambda control factor alters to 18 % (e). Under certain operating conditions the lambda performance map is shifted (arrow) by the ME control unit. This shifting of the lambda performance map is the self-adaptation of the mixture formation to the existing fuel-air mixture. After this self-adaptation the lambda control factor is again in the middle control range (g).

This self-adaptation of the mixture formation can be carried out in the following operating states:

• Idle speed
• Lower part load
• Upper partial load.

The following actual values can be read out using STAR DIAGNOSIS:

• Lambda performance map shift active
• Direction of the shift (tendency rich or lean)
• Size of the shift

Presentation of the self- adjustment values using HHT or STAR DIAGNOSIS in idle 

The representation in ms means that the value displayed is added to, or subtracted from, the air mass inducted by the engine in order to determine the injection time.

The maximum correction value is ±1 ms.

Example:

Calculated injection time (performance map): 3.0 ms

Displayed correction value: +0.3 ms

For determining the injection time (quantity of fuel injected) the ME control unit makes use of a mathematical value of 3.3 ms (3.0 ms+0.3 ms).

Presentation of the self- adjustment values using HHT or STAR DIAGNOSIS for lower and upper partial load 

The representation of the factor means that the indicated value for determining the injection time is multiplied by the air mass suctioned by the engine.

The correction factor lies between 0.68 and 1.32.

Example:

Measured air mass throughput: 150 kg/hour

Displayed correction value: 1.10 ms

A mathematical value of the air mass of 165 kg/h is used by the engine control unit in order to determine the injection time (quantity of fuel injected).

Flexible Fuel Vehicle (FFV) for engine 112 with code 929 

The ethanol factor has a multiplying effect on the fuel injection amount of 1.0 to 1.43 and leads to extended self-adjustment of the mixture formation.

	Motor electronics control unit, location/task/design/function	except for engine 104 HFM, 111 HFM, 111 EVO	GF07.61-P-5000F
		Engine 111 EVO	GF07.61-P-5000GS
	HFM-SFI control unit, location/task/design/function	Engine 104 HFM, 111 HFM	GF07.51-P-4103D
	O2 sensors, location/task/design/function		GF07.04-P-4103F
	Lambda control function	ME-SFI	GF07.61-P-4022F
		HFM-SFI	GF07.51-P-3011D