Fuel Injection System - Multi-Point: Description: Notes

The Multi-Port Fuel Injection system is standard on all turbocharged Pontiac and Oldsmobile 1.8L 4-cylinder engine. It is also used on Oldsmobile and Buick 3.8L V6 non-turbo engines. Buick 3.8L V6 turbocharged engines are equipped with the Sequential Fuel Injection system. Both systems share many common components and operating principles except for the following:

The Multi-Port Injection system uses Bosch injectors located at each intake port. Injectors are activated simultaneously, once each crankshaft revolution, on signal from the Electronic Control Module (ECM). The Sequential Injection system differs in that fuel is timed and injected sequentially into the cylinders. Each cylinder receives 1 injection per combustion cycle (every 2 revolutions) just prior to intake valve opening.

Both systems maintain constant fuel pressure to the injectors. Therefore, air/fuel ratio is adjusted by varying injector pulse width ("ON" time). The ECM processes information from various sensors to compute the pulse width. There are 2 major sub-systems; the fuel system and the electronic control system.