Fuel injection system refers to the system which is used to admit fuel into the engine of a vehicle. Fuel injection is achieved by fuel injectors, which open on receiving a signal from ECU and spray the pressurized fuel into the engine. Following are the different types of fuel injection systems –
Single-point or throttle body injection (TBI) – The first ever type of fuel injection system, it replaces the carburetor fuel-injector nozzles in the throttle body. There might be with one or two nozzles. This type of ignition system is now obsolete.
Multi-port or multi-point fuel injection (MPFI)- Such systems are used in case of more than one cylinder. Each cylinder has an individual injector nozzle, thus increasing the efficiency of engines. Types –
(a) Sequential – Injection is timed to coincide with intake stroke of each cylinder.
(b) Batched – Fuel is injected to the cylinders without precise synchronization to any particular cylinder’s intake stroke
(c) Simultaneous – Fuel is injected simultaneously to all the cylinders.
Direct injection – fuel is fuel is sprayed with the help of a nozzle into the combustion chamber (no air – fuel mixing before intake valve.
(a) Common Rail Direct Ignition (CRDi) – Fuel in the “rail” is under a set high pressure. Thus it gets atomized, leading to proper mixing with air, thus increasing efficiency of the engine. This system is mostly used in diesel engines
(b) Gasoline Direct Injection (GDI) or Petrol Direct Injection or Direct Petrol Injection or Spark Ignited Direct Injection(SIDI) uses the same technology for petrol engines. The air – fuel mixture is directly injected into the combustion chamber of each cylinder.