Fuel Control: Notes
The basic function of fuel control system is to control fuel delivery to engine. Fuel is delivered to engine by individual port fuel injectors mounted in intake manifold near each cylinder's intake valve.
The main control sensors are Oxygen (O2) Sensors, located in both right and left exhaust manifolds. The O2 sensor provides PCM with ratio to oxygen in exhaust stream to atmospheric oxygen. The PCM modifies Air/Fuel ratio by changing injector signal sent to each individual injector. By constantly measuring exhaust stream oxygen level and adjusting injector pulse width, air/fuel ratio is kept very close to 14.7:1. This is most efficient mixture to minimize exhaust emission. A 14.7:1 ratio allows Catalytic Converter to operate most efficiently. The constant tailoring of air/fuel ratio based upon oxygen sensor feedback is referred to as "Closed Loop" operation. See Fig 1 .