Confused by Fuel Trims

I've been trying to adjust my fuel tables (Fuel Mass vs Inj PW and Inj PW vs Fuel Mass) by means of data-logging while driving around (not using a dyno)

I will do start ups, easy driving, more aggressive driving in stages to dial in my fuel tables....

Just when I think I have my fuel tables dialed in based on the data-logging and the applicable adjustments to the fuel tables, I will go for one last drive to verify all the changes are still showing good LT and ST fuel trims and then all of a sudden ALL of the logged data will show that every cell in the fueling tables is way to lean or rich (30%) and I will have to start over again.

Each time I adjust the fuel tables I reset the adaptives, but there will be that odd time where the data log shows required fuel adjustments of 30% in every cell of the table.

What am I not seeing? It's like there is a hidden LTFT that just decides to reset itself to zero and screw everything up.

any help would be appreciated.

2012 Challenger, 392 based 426 with 2.9 Whipple, 6.2 cam, 80# injectors

Do you have a datalog and corresponding tune of the issue?
Are you logging other parameters that could effect the fueling such as ECT, IAT, MAT, PE etc?

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Originally Posted by HaasExp

Do you have a datalog and corresponding tune of the issue?
Are you logging other parameters that could effect the fueling such as ECT, IAT, MAT, PE etc?

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unfortunately no. I will make an effort to save the log with a name I can identify.

and just to clarify..... it's not like i'm making adjustments then driving the car two days later and this occurs.... I'm logging, I pull into a parking lot, make the revisions, upload them to the car, drive some more within minutes of making the changes and boom.... 30% correction required....

better people to answer than I, but log IAT and make sure it's not getting heat soaked while setting in parking lot between tuning runs...

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Originally Posted by rich s

unfortunately no. I will make an effort to save the log with a name I can identify.

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Please also post the tune file.

Try an extra key on, key off, wait 10secs then fire it up after completing flashing the update.
I have had this same thing happen at times...its like something messes up during flash procedure...strange but an extra key cycle usually sorts it.
Worth a try.