Contour Enthusiasts Group Archives Forums Modifications Forced Induction Diablo MAFia - How does it work?

Originally posted by ButtonPuncher:

---

OK guys hear me out...

The stock MAF puts out more than 5 volts when driven over it's stock flow. 7 volts definitely isn't out of range. Heck, if you regulated it, there's no reason that you couldn't push 9 volts. It is fed battery voltage. Don't believe me? My Fluke doesn't lie...



I'm saying that the Lightning/Cobra/Mustang MAF can be less accurate because you can't size it to your application. It is fixed. With the MAFia you can effectively vary the size of your MAF to fit your power level. That way you aren't wasting any resolution.

The stock Zetec MAF is just under 2.5" I.D.. Theoretically it should flow way more air than I will ever need. (And more power than most of you guys will need.) To quote...

Originally posted by DrFrankenbarge:

---

So if we go to the limit with 450 hp worth of air you're looking at around a 2.25" OD tube at 450 f/s (Mach .4). So to give yourself a little breathing room 2.5 should easily flow fine for 450hp.

Now say we are using this kit on a decent 2.5L and say we're making about 275 at the crank. For a velocity of 450 f/s you're looking at about a 1.75" OD tube (say 16 gauge wall).

---

This isn't snakeoil guys. It's a valid product. There isn't any voodoo going on. All that it is doing is scaling a voltage down. Pretty simple and very effective.

BP

---

Yeah, except that 12v battery voltage is for the sensor heater elements... NOT the sensing circuitry.
The maf works by heating one element and then sensing the change in temperature of the air passing over the second element...or something like that. It requires a heater a second element that has a changing resistance based on this heat change. This is also why the maf is a 3-wire or 4-wire sensor (depending if common or separate grounds) rather than just a 2-wire sensor.
Combined with all the electronics a 5v reference source is passed through the circuit and the varying resistance causes a voltage drop that the pcm compares with its stored data. The maf is calibrated and that calibration data plugged into the pcm. This is why there are so many different maf part numbers.

Ford makes enough mafs for their different cars that one is bound to have a measuring range that is suitable for what you expect to see on your engine. All the plugs are standardized for a given year or series of years. Just plug in, change the transfer function and away you go.

BTW, your aren't improving the resolution by changing the voltage if the pcm is still looking for the same voltage ranges. It will just approximate the closest value.
If your maf worked on a 0-5v scale but your intermediate circuitry allowed you to sense a voltage change down to the hundreths's column that reflected a change in airflow, THEN your resolution is improved. You have just possibly changed the range by changing the operating voltage range; and THAT would mean that your equipment isn't that precise and so therefore you needed a larger voltage range.