Digital stabilization of idle speed of the KE-Motronic system (Audi 100 C4)

The KE-Motronic control units have a digital idle stabilization, or DLS for short. This means that the transmitted signal is processed digitally. The electronic part of the DLS compares the width of the ignition pulse at idle with the nominal value and corrects deviations by changing the ignition timing.

When a powerful current consumer is switched on or the automatic transmission range is switched on, the engine speed decreases or the engine stalls altogether. In this case, the ignition pulse sequence drops below the value set in the DLS, the unit shifts the ignition timing in the advance direction by means of shorter ignition pulses. When the speed increases, the DLS is switched off.

Memorizing faults

Malfunctions in ignition or injection control that can damage the engine are recognized by the Motronic system itself. These malfunctions are stored by the control unit while the ignition is on. It is necessary to clarify what kind of malfunction we are talking about.