Fuel Adaptation

Fuel Adaptation





General
To compensate for e.g. normal manufacturing tolerances, ageing, etc., continuous deviations from lambda 1.00 are adapted. Fuel adaptation is divided into two sub-functions - multiplicative (partial load) and additive (idling). Together, these adaptations make lambda control work with a correction factor of around 1.00.

Multiplicative fuel adaptation





If lambda control is continuously correcting a deviation in the fuel system, it will be adapted. Adaptation takes place regularly while driving.

The fuel quantity is always multiplied by a multiplicative adaptation factor of 1.00 when the control module is new or has had its power disconnected. Multiplicative adaptation takes place under conditions of partial load. Purging is stopped during adaptation because other factors that can affect the fuel must not be active.

The entire lambda control deviation from 1.00 is transferred to the multiplicative adaptation factor. This makes it possible for the correct fuel quantity to be injected even when lambda control is not active, such as during a cold start.

After engine start, a multiplicative adaptation must always occur before an additive adaptation.

Conditions for multiplicative adaptation:
^ Coolant temperature over +60 degrees C.
^ Charge air temperature equal to or below +60 degrees C.
^ Load and engine speed within limits.

Additive fuel adaptation





If lambda control is continuously correcting a deviation in the fuel system, it will be adapted. Adaptation takes place regularly at idling speed. The additive adaptation, which is a 0.000 ms injection duration when the control module is new or has had its power disconnected, is always added to the fuel quantity. The additive adaptation takes place at idling speed. Purging is stopped during adaptation because other factors that can affect the fuel must not be active.

The fuel quantity is added or subtracted until the lambda control value fluctuates around 1.00 (0%). Additive adaptation is required because air leaks at idling speed will lead to a greater fault that must not be adapted multiplicatively as the fuel quantity would then be far too great when the load was increased.

Conditions for additive adaptation:
^ Coolant temperature over +60 degrees C.
^ Charge air temperature equal to or below +60 degrees C.
^ Load and engine speed within limits.