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