MAP sensor on MAF engine

23. When a MAP sensor is used on a MAF engine what is the primary purpose of the MAP ?
24. What is the mathematical formula called to measure incoming air flow on a MAP engine?

I think on a speed density engine it's grams per second

A map sensor on a maf engine is also used to determine barometric pressure.

I believe the term you are looking for in question 24 is speed density

Possibly used as part of a backup strategy during MAF failure?

Nissan Technician

23 - Primary purpose can vary. Some common stuff would be spark timing, BARO, speed density management (backup), airflow modeling.

24 - Take a look at the ideal gas law. That is foundational, but there is a lot more. For example, Chrysler spent a lot of money enhancing their calculation which is why they were able to skip using a MAF even with VVT systems etc.