An air-fuel ratio (AFR) is a measurement of the mass of air to the mass of fuel in an internal combustion engine. It is an important factor in determining the engine’s performance, fuel economy, and emissions. The ideal AFR for most gasoline engines is 14.7:1, which means that there are 14.7 grams of air for every gram of fuel.
There are a number of ways to check the AFR of an engine. One common method is to use an oxygen sensor, which measures the amount of oxygen in the exhaust gas. Another method is to use a wideband air-fuel ratio sensor, which measures the AFR directly.