In MPFI system, each cylinder of the engine has one injector which means multiple injector for each engine. Each of these Injectors are controlled by a small micro-processor, which controls each Injector about how much petrol and at what time it needs to inject near the cylinder so that only the required amount of petrol goes into the cylinder at the right moment.
MPFI systems can be of the following types
- sequential, in which injection is timed to coincide with each cylinder's intake stroke;
- batched, in which fuel is injected to the cylinders in groups, without precise synchronization to any particular cylinder's intake stroke; or
- simultaneous, in which fuel is injected at the same time to all the cylinders. The intake is only slightly wet, and typical fuel pressure runs between 40-60 psi.