Fuel trims in Lean Cruise

I had been seeing ltft showing up during lc and I wasn't sure if they were actually affecting the mixture or if the computer was just ignoring the fuel trims. Tonight I logged a stretch of road and attached are the logs. I filtered both logs and compared the bens of each log with each other. Let me know what you guys think. Its less than a 5% difference but to me it seems like there is a correlation.

in each log i started ate the startpoint and drove, then turned around and came back to the starting position.

Attachment 12445

Attachment 12446

LTFT should still show in the log, but since you are not in Closed loop for lean cruise the fuelling would not be affected by O2 sensor feedback.
I do not have Efilive on this computer, but will take the logs home to have a look.

Hi Greg,

Great idea for an experiment. As many already know, there are no STFT while in LC (logs will show 0) - the PCM runs in OL directly from the VE table. But your question - do the preexisting LTFT stored in the PCM memory impact (in anyway) on the final fueling while in LC - is not something I have ever looked into.

When the difference in the results are less than 5% from a road course test - it is difficult to infer causality. Someone with a chassis dyno and an inquisitive mind could probably settle this question.


Regards,
Taz

My observations is the LC uses it own tables and LTFT has no impact on it .

My Wide Band O2 sensor also shows no LTFT effect during Lean Cruise.