Gen 2 coyote MAF tuning question

[K44]

Lets say I put a MAF housing and tube that flows 20% more air. I then adjust my period table, do I also need to change the voltage table by the same amount as the period table.

IE add 20% to period only or 20% to both?

Thanks

[MRRPMBRP]

It's one or the other, not both.
Most likely digital, (period) what year?

[Bill88stang]

Period only, you can use the vcm scanner to log stft and ltft and the scanner will populate the data in the maf coloum and then you cast literally copy and paste the % diff. It will allow you to dial it in fast that way.

[K44]

Thats what I thought. Thanks.

Is ikt normal to have the MAF LT + ST trims change daily or every time I drive the car.

I can start the car and the trims will show pulling avg 5%, drive somewhere shut off the car do whatever I'm doing, return, start the car, drive home and the trims are now 0 to 2% avg adding fuel.

Rinse and repeat. Anyway I've been pulling my hair out over this.

Is this normal or do I have some mechanical problem

[Plimmer]

It’s normal for them to be up one day and down another. I’m lazy so as long as they are 8% or less I stop messing with it. Some say 5% but sometimes a 2% becomes 8% with changes in temp or new fuel in tank.

Best might be to use race gas with a constant blend so each fill up doesn’t add a new variable.

[K44]

Never thought about fuel blends. Thanks. I'll quit worrying about it.

[Bill88stang]

I zeroed out the maf temp table so it doesn’t mess with my trims depending on temp, but it’s just my preference.

[murfie]

LTFT can move +/- 5-6%(more?) as it cumulates and learns, LTFT attempts to keep STFT with in 1-2%. This is totally normal. LTFT is slow so if it is able to keep STFT around 1-2% the MAF curve is accurate.
It can also lead to LTFT+STFT being misleading if you are not paying attention to both separately. LTFT+STFT is to be used mainly when a change has the transfer really far off. When you are close disabling LTFT, to get STFT close manually, then reenabling LTFT is all you need to do. Then you can forget about it day to day.
The other way to do it is able only LTFT corrections a few times to get it close. Then apply enough correction to get STFT bouncing around 0% and thats it.
If done properly you never have to manually smooth the MAF transfer, the numbers just work out and it comes out looking like a proper smooth curve.

[K44]

Thanks Mark, that really gave me the light bulb moment. I now understand what the computer is doing with the data.

[K44]

One more question, Do i need to turn off anything other than the LTFT?

[murfie]

Cylair filter can be disabled. It modifies the actual air mass value, but usually takes a good amount of time before it does. Not really something you will see if you are taking a few minute log, flashing, repeating dailing in the transfer. If you are taking 30+min logs disable it.

Then some times people like to disable DFCO and any fuel rims relating to transient conditions (air charge delay compensation) just to not have to filter the data.