Throttle Position Sensor: Description and Operation

THROTTLE VALVE POTENTIOMETER
The throttle valve position is detected by a potentiometer located on the throttle valve shaft (arrow). The zero (idle) position of the potentiometer is detected adaptively by the DME control unit.

Adaptive control means that the control unit always identifies the smallest throttle valve opening angle as the idling position. If the throttle valve moves further open, after passing through approx. 1 the idling functions (cruise control, idling ignition timing 10° before TDC, cylinder filling control) are switched off by the control unit. Once the throttle valve's angle of opening reaches approx. 66°, the full load functions (full-load enrichment and ignition retard, fade-out of lambda control) are activated by the control unit.

In addition, when the vehicle is accelerated rapidly, i.e. when the throttle valve opens rapidly, the air conditioner compressor cuts out.