Oxygen Sensor System

OXYGEN SENSOR SYSTEM





An oxygen sensor system with 3-way catalytic converter was added to some models as early as 1979 in order to more effectively meet emission regulations.

The 3 way catalytic converter, which is capable of removing CO, HC, and NOx from the exhaust, can only work as long as the air/fuel ratio is kept within a precise range.

Fuel systems of the past, both carburetors and fuel injection, were incapable of maintaining a precise air/fuel ratio. For example, the air/fuel ratio of a simple carburetor can vary as much as 20%. Fuel injection systems offer better mixture control. Coupled with an oxygen sensor system, the air/fuel ratio in a fuel injected system can be controlled within a tolerance of .02%.

Basically, the oxygen sensor system works like this - a sensor located in the exhaust system senses the oxygen content of the exhaust gases. The amount of oxygen in the exhaust varies according to the air fuel ratio. The oxygen sensor produces a small amount of voltage that varies depending on the amount of oxygen in the exhaust, and this voltage signal is sent to an electronic control unit.

The electronic control unit works together with a frequency valve which will vary the amount of fuel delivered to the engine.

With the oxygen sensor system, the air/fuel ratio can be kept within the precise range required for efficient operation of the 3 way catalyst.