The levels of carbon dioxide exhaust emissions are highest when the air/fuel ratio is lean.

Question

Quizplus · Accepted Answer

The levels of carbon dioxide (CO2) emissions are highest when the air/fuel ratio is rich, not lean, because a rich mixture means more fuel is being burned relative to air, leading to higher CO2 production. Lean mixtures burn less fuel and more air, resulting in lower CO2 emissions but potentially higher nitrogen oxides (NOx) emissions.

The Levels of Carbon Dioxide Exhaust Emissions Are Highest When