LTFT’s stuck-what does this mean?

[Stkid93]

What does it mean if your long term fuel trims are stuck at a specific number but your short term fuel trims are not. (Just had a part installed and tying to see if it caused the problem)

currently my LTFT is stuck at 9.38 and will only slightly move down to 8.6 at wot. But will not move other than that no matter throttle placement or rpm range. Before the install it would fluctuate between 6-9% depending on how much throttle and Rpm range. When I at idle the reading would be 1 number and it would change based on throttle input.

what does this mean?

 

[Dialcaliper]

It basically means your ECU is doing exactly what it’s supposed to and has adapted to any changes you’ve made to the car.

Short term trims will always jump around to adjust for little things that cause AFR too change from intended (temperature, humidity, the latest tank of gas, etc), but long term trims only adjust when short term trims stay in one direction consistently - the short term adjusts for rapid changes while the long term is supposed to reflects the adjustment for how your engine is configured in comparison to the factory’s test engine (or the map your tuner gave you)

That’s the theory anyway.