Car Articles

The modern car engine has come a long way from industrial engineer Gottlieb Daimler’s first car engine created in 1889. A century of innovations has transformed Daimler’s humble 4-step combustion engine into the highly efficient, powerful, and complex engines. The application of electronics has only complicated matters further. The common man is left groping in the dark trying to understand car engine jargon such as ECU, DOHC, SOHC, OHV, EFI, MPFI, and CRDi to name a few. Car engine terminologies have expanded to such boundaries that entire books can be dedicated to understanding and researching each. The purpose of this article is to provide an overview of one of the most fascinating car engine technologies ever invented - MPFI (Multi-Point Fuel Injection).

Before attempting to understand MPFI, it is necessary to have a basic idea about fuel injection in general. Simply put, fuel injection is the process of systematically injecting fuel (petrol or diesel) into the car engine in order for it to burn and produce energy to move the car forward. As simple as it sounds, the role of fuel injection is important when it comes to the performance and efficiency of an engine. Inspite of this, fuel injection wasn’t really a great deal during the car engine’s early years as the focus then was on reducing its large size to something more portable. The need for more efficient fuel injection systems was felt while car manufacturers competed to create better engines. The need was even felt strongly as public awareness of the scarcity of fossil fuels spread and their prices simultaneously soared. The MPFI was born out of these needs.

In an MPFI or Multi-point Fuel Injection system, fuel is injected into all cylinders of an engine either in sequence (one after the other) or simultaneously. The injection pattern is controlled by an onboard computer called the Engine Control Unit (ECU). Three different injection patters are possible on modern engines. The first is ‘Sequential Injection’ in which fuel is directly injected into individual cylinders of the engine in sequence. The injection into each cylinder is done when the piston inside that cylinder is in downward motion at the time and thus sucking air into the cylinder. This action is similar to the operation of a syringe when the plunger is pulled out. This phase of the engine is called the suction stroke and all fuel injection happens during this cycle of the engine. The second fuel injection pattern under MPFI is ‘Simultaneous Injection’. Here, fuel is injected into all cylinders of the engine together. The biggest advantage of simultaneous injection is speed. It erases the need of each cylinder to wait for the other cylinders to be injected in sequence until its turn arrives. ‘Group Injection’ is the third pattern of fuel injection and this is similar to sequential injection in a way. The cylinders of the engine are split into groups of 2 or 3 instead of being considered individually and each group is injected in sequence much like in sequential injection. These three ways of fuel injection deliver high engine performance and balanced power output.