Fuel System Monitoring (HFM-System)

Fuel System Monitoring (HFM-System)

Mixture adaptation
In the ECU the injection time is calculated from: 1) an HFM based basic load signal, 2) an additive correction of the mixture adaption, 3) a multiplicative correction from the lambda controller, and 4) a multiplicative correction of the mixture adaptation. All correction factors are calculated at any time during engine operation.

The mixture adaptation has 3 adaptation ranges. The learning integrators are thus activated in different speed and load ranges. The deviation of the Lambda controller from it's neutral value (1.0), is learned in one of the integrators at idle, at medium load / speed, and at very high load / speed.

The diagnosis of the fuel delivery system conducts a check of the output values of the above mixture adaption. If one integrator exceeds its error threshold, the MIL is illuminated. This functionality is split into two parts: empty fuel tank detection and the threshold evaluation function.