Depends on how far off your MAF is, most likely, with a base adjustment the car will be fairly driveable. If so, you can use LTFT's. I don't know if this is a simple, use STFT or LTFT question, but I thought I might as well include the how to info.
Take your stock inner intake tube diameter, assuming you have a 5.0 Coyote Mustang, it has a stock inner intake tube diameter of 86mm (inner radius of 43mm)
The surface area of the inside of the intake tube can be calculated using pir^2 : (pi)(43^2) =
5808.8
Take the inner tube diameter of the new intake, assuming you have a JLT Intake, has a inner tube diameter of 107mm(inner radius of 53.5mm)
The surface area of the inside of the intake tube can be calculated using pir^2 : (pi)(53.5^2) =
8992.02
8992.02 /5808.8 = 1.548
Multiply the entire MAF Airflow vs. Period table by 1.548 and flash this tune to the car. Doing this with my V6 Mustang right away got the MAF Curve within 3% in most driving conditions, but the car was 12% rich at idle, so there was still work to do.There is no need to disable any form of adaptive learning in the tune when using LTFT's, which is nice. STFT's switch quick and LTFT's consistently build fueling correction. Also if I don't datalog the car, the computer does it for me by remembering the LTFT during different driving conditions, the next time I datalog the car, the learned LTFT data is there.
The next thing to do after that base correction is made, is to setup a histogram to log MAF Period.
2.25 Scanner may or may not support all of the parameters needed to tune the MAF, here is how I did it in 2.24
1. Define a custom PID for MAF Period
Attachment 54111
2. Setup the table display to include the following parameters at a minimum:
LTFTB1(SAE),LTFTB2(SAE),MAF Hz and the user defined PID you created for MAF Period.
3. Setup a histogram to relate LTFT's to MAF Period.
General & Plot
Attachment 54112
Row & Col Axis
The data in the labels box is simply copied from the period axis inside the MAF Airflow vs. Period Table in your tune. You have to use commas in between values in the labels box!
Attachment 54113
4. Go on a drive, let the car learn and generate LTFT data in as many different driving conditions as possible. As it records, it will populate your histogram table. You can now use this data to tune your MAF.
Attachment 54114