The MPI on an automobile stands for multi-port injection. The fuel injection system replaces the carburetors on the combustion engine. The systems where developed to meet the federal emission requirements, as well as the corporate fuel economy requirements. MPI is a newer type of fuel injection system than the original single-port fuel injectors.
Fuel Injection
Fuel Injection Combustion engines work the same way they did when carburetors were being used. A vacuum pulls air and fuel into the engine to control the speed of the engine. Instead of the carburetor controlling the amount of air and fuel being sucked into the engine, the fuel injection system sprays the fuel and air into the engine. Carburetors were good components, but fuel injectors provide the engine with a more accurate amount of fuel when required. Originally the fuel injectors were single port systems that spray fuel into all the cylinders, but a multi-port injector has become common.
Multi-port Injector
The MPI and the multi-port fuel injector (MFI) component is the same thing, just different terms. What the MPI does is spray fuel into each cylinder as it is needed. The amount of fuel required by each cylinder is determined by how much air the cylinder is attempting to suck in. Each intake valve gets a specific amount of fuel sprayed into it from a multi-port injector system.
Sensors
Most people know that automobiles have computer systems installed in today’s modern vehicle. Part of that computer system uses sensors to determine how much air each cylinder is sucking into the engine. The sensor informs the computer what amount of air the cylinder is sucking in. The computer makes a calculation, then tells the multi-port injectors how much fuel must be sprayed into that intake valve.
Efficiency
Since the exact amount of fuel requred is sprayed into the intake valve, no wasted fuel is being burned by the engine. As the multi-port injectors become more efficient and exact, the automobile’s fuel economy will increase. Fuel economy is not the only thing that takes advantage of a multi-port injector, the car’s emission is lowered because wasted fuel is not being sent through the exhaust system.