Posts Tagged: positive fuel trim causes

Fuel Trim: What the numbers mean

Fuel Trim Explained: What the numbers mean and how to use the data to diagnose your engine Quick Summary: Fuel trim in an OBD-II vehicle is the engine computer’s ongoing adjustment of fuel injector duration to keep the air-fuel mixture as close as possible to the ideal 14.7:1 ratio. Using feedback from the oxygen sensors, the ECM monitors whether the engine is running rich (too much fuel) or lean (too much air) and instantly alters short-term fuel trim (STFT) to correct the mixture. In contrast, long-term fuel trim (LTFT) stores … Read More