Fuel Delivery and Air Induction: Description and Operation

System Schematic:

The MPI engine management system is a fully electronic ignition control and multi-point sequential fuel injection system. The system is similar to the Bosch LH-jetronic system and combines fuel injection and ignition control functions into a single electronic control unit (ECU). The ECU monitors various engine sensors and uses this information, compared with information stored in its memory, to precisely control the fuel and ignition systems for lower exhaust emissions, better fuel economy and better engine performance, under all operating conditions. Fuel is supplied to the injectors under high pressure. Fuel pressure is regulated by a vacuum operated pressure regulator. Injectors are operated electrically by the electronic control unit. Injection quantity is metered by varying the length of time (duration) that the injectors are energized, depending on signals from a hot wire air mass sensor in the intake system, along with other sensors.

The primary fuel and intake system components are covered here. For information about the computer, controlled devices and information sensors, refer to COMPUTERIZED ENGINE CONTROLS.