Found a real good article explaining fuel trims. Watched a lot of videos and read a lot. This article seems a little easier to comprehend.
Fuel trim: How it works and how to make it work for you
When diagnosing a check-engine light or drivability issue, you can learn a lot by looking at fuel trim data on a scan tool. Fuel trim can be affected by just about anything between the air filter and the muffler, including sensors, injectors, ignition, EGR, the engine’s mechanical condition and...
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