Closed loop control of automobile engines

Closed loop control of the fuel-air ratio of automotive engines has become widespread in production vehicles. Its purpose is to maintain a sufficiently high accuracy for simultaneous reduction and oxidation of the exhaust emissions in spite of fluctuations in environmental conditions, manufacturing tolerances, and time degradation of the components. Spark advance is also being controlled using accelerometer feedback in some production vehicles to allow a more efficient setting while virtually eliminating detonation even with fluctuations in fuel octane, inlet air temperature and humidity. The benefits of using feedback in these situations have been found to be high enough to warrant their extra cost.