M. Red WS6

Has anyone ever had an issue with their fuel trims going lean during the summer with a tune developed during the winter? I tuned my car during the winter and was averaging -2 to +2 on LTFT but now they are mostly lean ranging form +3 to +7. Could the transition of gasoline (winter to summer) have anything to do with this to impact my fuel trims now?

YellowToy/A

iTrader: (1)

Cold air is has more mass. That is why the are fuel trims. Hot humid air has alot less mass than col dry air.

Billf6531

If that's the case (and I know that your description of air mass IS correct), why are his trims adding fuel instead of removing fuel? What sensor component or PCM table is lying to the PCM?

M. Red WS6

I agree with your response Yellow Toy/A but as Billf6531 said I would have expected the fuel trims to be a bit more negative. By the way I have already added some fuel to the fuel trims adjusting the VE in the 800 - 2800 RPM,
30 - 65 kPa range, but I did not notice that much of a change. The only thing that I have done differently is disconnect the MAF which was connected during the winter tuning that I was doing. But I doubt that is the issue given that the MAF was dissabled at the begining of the tuning. Anyone else have any input? I am at a loss i will reconnect the MAF and keep logging and report back if anything changes.