What is TPFC?
The term TPFC stands for Transient Power Fuel Control system. This system uses a constant choke carburettor. The most prominent feature of this type of carburettor is that it increases the engine speed without any jerks. In this system, the throttle valve creates vacuum which opens a slide. It eventually controls the air-fuel ratio through a tapered jet.
Most bikes use ‘Constant Velocity’ carburettor. This type of carburettor maintains constant velocity at the Venturi. This produces optimum air-fuel ratio. However, this type of carburettor has a slight lag / delay when the rider opens the throttle suddenly.
How TPFC Works?
This is where Transient Power Fuel Control system comes into play. It's nozzle mechanism sprays petrol when the rider opens the throttle suddenly; thereby instantly revving the engine. This increases the throttle response and engine feels livelier. However, this increases the emission levels. Hence, TPFC was consequently discontinued as the fuel injection technology later replaced the carburettor.
If the rider opens the throttle without needing it activates the Transient Power Fuel Control system and will accidentally waste some fuel. Typically in TPFC, an accelerator pump injects more fuel to compensate for the lean air-fuel mixture which it generates when rider applies sudden throttle. The pilot circuit in combination with the needle and needle jet normally has enough rich setting so that, it does not need extra enriching from an accelerator pump.
Advantages of TPFC:
Basically, the Transient Power Fuel Control system is a technology which offers dual character to a small engine. It does so by increasing the air-fuel ratio as and when the throttle requires. This ultimately results in higher engine power / performance.
Additionally, the special feature of the TPFC (Transient Power Fuel Control System) is that it handles sudden acceleration with ease. Furthermore, Hero also provides an air filter element which injects fresh air into the exhaust to meet emission norms. It makes this bike ‘eco-friendly’. According to Hero Motocorp, it helps to keep the environment pollution free. Hero Motocorp employs Transient Power Fuel Control System in its Hero CBZ model.