This is my basic write up, and no I am not linking to sources yet in this version.
?Wideband? Air to Fuel Ratio Controllers,
and Their Uses in Modern Car Tuning
An internal combustion engine creates its power from burning a mixture of oxygen and fuel (the type of fuel may vary depending on the design of the engine). The relationship between the oxygen ?air? and fuel inside the ignition chamber of the motor greatly changes fuel economy, power, exhaust gas production, and efficiency of burn. The two most common ways of supplying fuel are carburetors or fuel injection. Both the carburetor and fuel injector were designed for the same basic goals; to mix just the right amount of fuel with the air pulled into the engine so that the combustion of said air and fuel burns properly. If there is not enough fuel mixed with the air, the engine "runs lean" and either will not run or potentially damages the engine. If there is too much fuel mixed with the air, the engine "runs rich" and either will not run (it floods), runs very smoky, runs poorly (bogs down, stalls easily), or at the very least wastes fuel. Both the carburetor and fuel injection system are in charge of this air to fuel ratio and its operation. This project discusses the usage of a ?wideband? air to fuel ratio controller and taking the signals from the air to fuel (A/F) ratio and creating more power and efficiency from the engine.
The last car in the United States to feature a carburetor was the Subaru Justy in 1989, but to keep up with ever increasing United States clean air laws, every manufacturer switched to a fuel injection system by 1990. The fuel injection system that will serve as a basis for this project is this project, along with being the most common, is known as multi-port fuel injection other wise known as sequential fuel injection. These systems have a fuel injector for each cylinder, usually located so that they spray right at the intake valve. These systems provide more accurate fuel metering and quicker response. The car used as an example for this project is a 1996 Mazda Miata, which has 1.8 liter (1839 cc) fuel injected four cylinder motor which will be further referred to as the ?BP? as this is the model name given to it by Mazda.
The Oxygen Sensor
The ?perfect? mix of gasoline and oxygen in the BP, and most modern engines, is 17:1. Too much fuel and the combustion runs too ?rich? which results in wasted fuel and increased amounts of hydrocarbons, otherwise known as the greenhouse gasses. Too much oxygen and the motor will run ?lean? which creates larger amounts of nitrogen-oxide pollutants and could lead to sever engine damage. It is safer for the motor to run more rich than lean in most cases. Either a rich or lean condition will result in poor engine performance.
The oxygen sensor is located in the exhaust pipe and meters the gasses as they escape from the engine. The patent for a modern oxygen sensor describes the process in which the sensor monitors the gasses as:
An oxygen concentration detecting device has a solid electrolyte made of a partially stabilized zirconia on one face of which is formed a measuring electrode exposed to a gas to be measured and on the other face of which a standard electrode exposed to a standard gas. An oxygen concentration detecting device provided with a protecting layer covers the measuring electrode formed on the oxygen concentration detecting device on the face exposed to the gas to be measured, the protecting layer being made of a partially stabilized sintered material of a partially stabilized zirconia material having a specific surface area of not less than 3 m2 /g and not more than 6.4 m2 /g to which a divalent or trivalent metal oxide, such as yttria, is added.
The sensor takes this information and proves a 0v to 5v current which is intercepted by the Electronic Control Unit (ECU) which acts as the controlling force for all the events required in the operation of the automobile.