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Idle speed control

Idle speed control


Idling speed with the Motronic 4.1 is controlled by means of a two-winding idle air control valve with the aid of PWM signals from the control module.

Automatic idling control is adaptive, that is to say it adapts continuously to the changes which take place throughout the life of the engine. Such changes might be wear in the engine, dirt or leakage in the intake manifold or throttle body, etc.

The control module is programmed to maintain idling speed at a constant 900 ± 50 rpm when the engine is at normal operating temperature and the throttle position sensor indicates that the throttle butterfly is in the idling position.

Engine speed compensation occurs on engagement of the A/C, if a gear other than P or N is selected on cars with automatic transmission, when the control module activates the secondary air injection system, and when the radiator fan cuts in.