Fuel System Monitoring

Fuel System Monitoring

The fuel injection system has a function which compensates for changes in the lambda (lambda) control which occur slowly over its service life. It is called lambda adaptation and its purpose is to keep the integrator signal within its limits of control (see figure below).

The integrator signal controls the fuel injection time, in a new car the integrator signal oscillates about 1 (equivalent lambda=1).







The amount of lambda integrator offset is calculated when the set lambda is equal to 1 and the canister close valve is closed.

The fuel adaptation will compensate the fuel amount so that the lambda integrator will remain in the middle (lambda=1.0).

The lambda control adaptation is divided into two adaptation areas: The additive adaptation at idle conditions (ora) and the multiplicative adaptation area at loaded engine (frau).

The correction of the fuel amount = calculated fuel amount * frai + ora. The speed of the fuel adaptation is depending on the lambda integrator offset (big offset is equal to high adaptation speed). The amount of the lambda integrator offset is also used in calculation of the physical urgency. The purge functionality is also calculating a physical urgency (dependant of charcoal canister load). This means that the fuel adaptation will get more time for adaptation if there is an offset and/ or low charcoal canister load.