Understanding AFR: What is AFR?
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What is AFR?
01.10
| 00:00 | Air fuel ratio or AFR is the way we as tuners most often refer to the fuel mixture the engine is running at. |
| 00:08 | As it’s name implies, AFR describes the ratio of air to fuel. |
| 00:13 | This is one of the primary indicators we are watching and adjusting when we tune an engine. |
| 00:18 | Since the airflow through the engine is a function of engine capacity, RPM, and volumetric efficiency, with the exception of aspects like continuously variable cam control, we can’t influence the airflow from the laptop key board. |
| 00:33 | We can however adjust the fuel delivery and this is how we can adjust the mixture the engine is running at. |
| 00:40 | One important aspect to understand here is that when we talk about AFR, what we are interested in is air mass, not volume. |
| 00:49 | This is because air fuel ratio describes the ratio between molecules of oxygen and molecules of fuel. |
| 00:56 | Mass can be effected by both temperature and pressure. |
| 01:00 | This is why it is critical for the ECU be able to accurately measure or calculate the mass of air entering the engine. |
