•  The fuel consumption at idle is mainly determined by the idle speed and efficiency. It is advantageous to have as low an idle speed as possible, as idling is of considerable importance when driving in dense traffic (for minimising fuel consumption). However, the idle speed that"s selected must be sufficient to ensure that, under any condition (e.g. when the air conditioning is switched on, or the vehicle electrical system is heavily loaded), it will not drop so low that the engine starts to run roughly or stalls.

•  To regulate the idle speed, the injected fuel quantity is varied by the idle speed controller until the measured actual engine speed is the same as the specified target engine speed.

•  The set engine speed value and the control characteristic are influenced by the engine coolant temperature.

•  Other variables are: