1 - body; 2 - throttle valve; 3 - idle bypass channel; 4 - idle air adjustment screw
The "Motronic" system uses a potentiometric sensor, the signal from which is used to determine the engine operating mode.
The throttle body consists of the body itself, the throttle valve, the idle bypass channel and the idle air intake adjustment screw. The amount of air entering the engine is determined by the degree of opening of the throttle valve, electrically connected to the accelerator pedal. In idle mode, the air required to form the hot mixture enters the engine intake channel through the gaps between the edges of the throttle valve and the body, as well as through the bypass channel. The amount of air passing through the bypass channel and, consequently, the engine crankshaft speed in idle mode is adjusted by the screw at the manufacturer.
With the throttle valve closed (idle mode) or fully open position (full load) — the corresponding signals are generated for the ECU-KSUD, which, based on them, stops the supply of injector control pulses or issues a command to enrich the mixture. In the intermediate position, partial load commands are generated.