"A throttle position sensor (TPS) is connected to the shaft of the throttle plate to provide the ECU with information on whether the throttle is in the idle position, wide-open throttle (WOT) position, or somewhere in between these extremes" - Wikipedia

TPS essentially tells the ecu what is the relative position of the butterfly valve. If the ecu is connected to a computer using appropriate software one can see that the TPS setting has a value ranging from 0-100. 0 being a fully closed butterfly valve and 100 being fully open one (also known as WOT).

This is combined with other parameters using various sensors i.e
air temperature sensor
intake manifold air pressure (MAP) sensor
coolant temperature sensor
camshaft position sensor (which tells the ecu what the intake and exhaust valves are doing)
crankshaft position sensor (which tells the ecu what the position of the piston is)
lambda sensor (measuring air:fuel ratio indirectly by analysing exhaust oxygen content)
fuel pressure sensor
knock sensor
engine speed (rpm)
idle air control valve (IACV)

NOTE: NOT ALL ENGINES UTILISE ALL THESE PARAMETERS SO DON'T PANIC IF YOUR MODERN BIKE DOESN'T HAVE ALL THE SENSORS (especially knock sensor and fuel pressure)

This then enables the ecu to tell the injector(s) as to how much fuel to supply to the engine and at what point in the combustion cycle and also tells the ignition unit at what point and for what durationto to give the spark (usually at TDC or top dead centre) to give optimum combustion. The end result is optimum power (read that as "kitna power hai") and fuel efficiency (read that as mileage or what gives us the "kitna deti hai").

This also explains why modern engines with ecu's are more efficient compared to older engines.


A simple schematic: Inputs from the various sensors (red rectangles) go to the ecu which in turn controls A (fuel injection) and B (spark).

Clemson Vehicular Electronics Laboratory: Engine Control