Tuning maf without disabling anything. What could go wrong?

I have been driving my car a lot. And slowly I have been making adjustments to the MAF airflow frequency in baby steps in accordance to the LTFT's. I am noticing that it is actually making a difference. Initially it was at +18%. I changed the whole airflow table to a stock table and that brought the LTFT's to -12% Then from there, I slowly made changes to the whole table by reducing the table by small percentages. (multiplication) Got it down to -3% and even -1% to .8% in some areas. My goal was to keep it on the negative side from 0% to -3% and it looks like I am succeeding. (Part throttle tuning) I want it zero to negative so that fuel is not added to PE on WOT.

I know that the way its supposed to be done is t disable the fuel trim control and the SD interference. But I decided to try making small changes and at the same time learn the basics of HP Tuners. And it seems to be working. It does take longer doing it this way but since I drive the car a lot, I can see the changes over time and can tune at my convenience. Car runs great.

My question is what is the downside to this method?

E38 ECU with LS3/L99 hybrid engine in a Chevy Nova. Wideband is installed and I will soon integrate it into the logging software for future tuning as I continue to learn.

Are you using any filters to weed out the transient data?

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Originally Posted by PGA2B

Are you using any filters to weed out the transient data?

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^^ This! If you filter out some unwanted stuff (DFCO/CFCO/deceleration, EVAP states, etc.), you can get CL trims on a MAF lined up in short order. I suggest filtering on fuel trim cells, intake valve temp, coolant temp, and throttle rate of change for starters. Get rid of the fuel trims cells that you don't want (15 and 7 usually on an LS3), only look at data when the IVT's get over some minimum (e.g. 305) and/or coolant temp is above some minimum, and use the forward-looking slope function for 2 or 3 seconds with throttle position to make sure you are at a steady state. That will get good data for you.

Don't know your mods, but look out for COT if you have it enabled. It can throw off your fueling and make you chase your tail.

No filters at all. I don't have cats or evap stuff. It has vvt.

I understand that the "proper" method is to disable a few things. But my question is if doing it the way I have been doing it is ok and would not mess anything up with drivability in the long run.? So far its running pretty good and technically I could just leave it the way I have it and keep doing small adjustments over time. But I want to know the consequences if there are any.

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Originally Posted by RobZL1

I suggest filtering on fuel trim cells....l.

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Originally Posted by PGA2B

Are you using any filters to weed out the transient data?

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any info, links to how to filter these items?
would be great to only log above 20 mph and filter out small acc pedal movements.. ?

There are several ways to create filters. Here is a google search to get you started. Read up and create filters for what you want to filter out.

https://www.google.com/search?q=hptu...hrome&ie=UTF-8