Definition of Lambda Air-Fuel Ratio

Written by amy rodriguez
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Definition of Lambda Air-Fuel Ratio
Air and fuel ratios are imperative for proper engine functioning. (The modern car at petrol filling station image by terex from

A car's engine is dependent on proper air-to-fuel ratios for peak combustion rates within the engine's interior. A value of measurement that is helpful to technicians for adjustment processes is the lambda air fuel ratio.


A lambda air-to-fuel ratio is another way of expressing the value of the air and fuel mixture inside an engine's combustion chamber. Instead of a comparison of numbers, such as 12-to-1, the lambda value is more accurate, as stated in a decimal value, like 1.051.


This lambda value is derived from a lambda meter placed in the exhaust gas of a vehicle. As the gas passes across it, the quantities of carbon monoxide, carbon dioxide and oxygen are calculated and displayed for the technician. This results in a precise adjustment of the air and fuel mixture.


A lambda value that is equal to 1 is a correct air and fuel mixture for complete combustion. If the lambda value is higher than 1, then more air than fuel is present. In contrast, when the lambda value is lower than 1, the mixture has too much fuel.

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