7.1 Basic / Load Sections 7 ADDITIONAL ITEMS: BEYOND BASIC FUEL AND IGNITION CONTROL
• MAF sensor range - sets the range to match your MAF sensor. Set this before loading a MAF calibration
curve. On gasoline, 650g/s ~800hp; 1300g/s ~1600hp; 1950g/s ~2400hp and 2600g/s ~3200hp. Use the
lowest range suitable for better low-end precision.
• MAT correction table - this curve allows adjustment of flow values from the loaded calibration curve.
• Use old-style calibration curve - select this if you want to use MAF in the “old way” as per 1.1.x and earlier.
In this case, the calibration curve is not the actual flow curve, but a trim curve applied to the calibration curve
loaded in the Tools menu. See section 7.1.11 for details.
7.1.12.1 More about frequency based MAFs Some GM MAF sensors are known to give a frequency output
rather than an analogue voltage. This has the potential advantage of not being susceptible to any ground differ-
ences. Due to the way that the frequency is measured, the reading becomes more coarse at higher frequencies.
At 10kHz the measurement has 1% accuracy, 15kHz is 1.5%. For better repeatability, it is suggested to get a larger
MAF and recalibrate in preference to running above 10kHz.
Be sure to set the minimum and maximum frequencies before altering the flow curve. Pre-defined calibration
curves are available for GM LT1, LS1, LSx MAFs. When using the 650g/s file (~800hp) set the min/max frequencies
to 1000Hz and 11500Hz. When using the 1300g/s file (~1600hp) set the min/max frequencies to 1000Hz and
14125Hz. For larger flowing MAFs, a custom calibration will be required.
7.1.13 MAF flow curve
This will bring up the MAF calibration curve, showing airflow as grams per second as a function of voltage or
frequency. Ideally, you should start with the curve that matches your actual sensor. Some examples are provided
in the software package that may be loaded with File > Load Dialog Settings.
(This one curve replaces the Calibration and Correction Curve that were used in previous firmware releases.)
7.1.13.1 MAF Load As shown above, the primary fuel load is MAF because fuel required is directly related to
mass air flow. However, ignition, AFR, and other load based tables are not directly related in the same way. While
it would be possible to use MAF volts as the Y-axis on other tables, it would mean that only a very narrow band of
the table was used, and tuning would suffer. So instead of that, the code calculates a synthesized load value called
AMP EFI MS3Pro manual version 1.202, firmware 1.5.0, 4/21/2017 Page 147
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