Difference between MPFI and CRDI

The major difference between the MPFI and CRDI systems is that the MPFI is used in petrol/gasoline engines while the CRDI system is used in diesel engines to control the supply of fuel.

Difference between MPFI and CRDI


The multi-point fuel injection is the type of indirect fuel injection system used in gasoline engines. It consists of the fuel injectors fitted before the intake valve of each cylinder. The fuel to the fuel injectors is supplied by the common rail which is pressurized by the fuel pump.

The opening of the nozzle is controlled by the ECU. The ECU takes input from different sensors about engine RPM, flowrate and temperature of the air, etc. to control the opening of the injectors.


Common rail direct injection is the fuel injection system used in diesel engines. The fuel injectors in the CRDI system inject the fuel directly into each engine cylinder. All the fuel injectors are connected to the common rail for the fuel supply.

The higher pressure inside of the common rail is maintained by the two fuel pumps:  A high-pressure pump, and a low-pressure pump. In CRDI the opening of the fuel injectors is controlled by the ECU unit. The ECU unit takes the input from the throttle sensor, pressure, and temperature sensor, oxygen sensor, etc. to control the opening of the injector.

Difference between MPFI and CRDI system:

1MPFI stands for multi-point fuel injection.CRDI stands for common rail direct injection system.
2It is used in petrol or gasoline engines.It is used in diesel engines.
3Fuel is injected into the runner of the intake manifold before the intake valve.Fuel is directly injected into the combustion chamber.
4The system uses a single fuel injection pump.The system uses two fuel injection pumps: Low pressure and high pressure.
5The system operates at a lower pressure than the CRDI system.The fuel pressure is higher than the MPFI system.
6The cost of the MPFI system is comparatively lower.The CRDI is expensive.
7It has a comparatively lower maintenance costThe maintenance cost is comparatively higher as it operates at higher pressure.

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Pratik is a Graduated Mechanical engineer. He enjoys sharing the engineering knowledge learned by him with people.

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