When the micro-controller circuit is switched on, the
voltage signal from the Throttle Position Sensor
(TPS) goes into the controller depending upon the
amount of flow of air through the throttle valve. The
micro-controller receives the signal from the TPS and
processes on the received data and produces a
pulsating 12 V signal which goes to the fuel injector
which is connected to a small plate type sensor and
control mechanism of needle valve. Depending upon
the flow of air through the throttle valve, the amount
of fuel injected by the fuel injector is controlled by
the control signal applied by the micro-controller.At
the idling, the frequency of signal is set high in
micro-controller and when the engine is accelerated
by opening of throttle valve, depending upon the
different load conditions, the frequency of a pulsating
12 V signal decreases and simultaneously the
quantity of fuel injected increases with increase in the
amount of sucked air during suction stroke by more
opening of needle valve of fuel injector. Thus, the
air-fuel mixture is kept constant throughout the
working of engine on particular operating conditions