The MAF measures airflow into the engine, so that the LH knows how much fuel to inject. It's a voltage signal to the LH, and there is a limited range-- if the airflow gets high enough then the MAF signal just hits the stop and can't go any higher. So airflow increases, but the LH doesn't know that and doesn't increase the fuel proportionally. That causes the mixture to go lean, which is bad.

There is enough range in the standard MAF for about 450 crank hp (figure 380 at the rear wheels) before it hits max. That's not a precise number, because air density depends on altitude, temperature, etc. But generally a "stage-1" kit running around 6 psi boost will be fine with the standard MAF. Add an intercooler or more boost and you need to expand the MAF's measurement range.

That's where (ta-dah!) SuperMAF comes in. The MAF signal is compressed at the higher flow rates so that the measurement capacity is greatly increased. This requires different programming in the LH, because the measurement scale is different, but that's all built into Sharktuner. So a regular MAF and SuperMAF are physically the same, but cannot be interchanged without reprogramming the LH with Sharktuner-- or getting a set of chips or PEM's (flash memory chips) that were set up for SuperMAF.

I hope this helps.

 

Awesome. That is a fantastically simple explanation for a simple guy like me! I understand perfectly now. Looks like I need a superMAF because the SC will be stage II.

Now the question that begs to be asked is that I have two good MAFs (two engines - long story) and it would be a shame to rip one apart to make a superMAF. I guess I should contact Louie and exchange a regular MAF for a superMAF. Should be a simple transaction.

Love your responses Jim. Things are much clearer after your explanations which are in clear simple terms because... (wait for it, because i very rarely get to use this line,) Damn it Jim! I'm a cabinetmaker not a magician

 

The exchange price for stock MAF to SMAF depends on both electrical and physical condition of the donor unit. Best case for the upgrade is 150 USD, worst case $450. Louie would be able to advise when he tests and inspects the donor MAF.

 

I had a MAF fault (#21 Mass Air Meter) last weekend and had many of the same questions. Thanks for the great explanation Jim.

 

It is a bit like buying a used light bulb....we all know it will eventually burn out and the newest original 928 mass air is now nearly 20 years old. And it is a fact that they degrade over time and heat cycles (the element glows red hot to burn off contamination after each run).
So "known good" is going to mean the car runs.....not necessarily well or will pass any emissions tests....just runs !

 

I have rebuilds in stock for $295 plus a $350 core charge - hard to get people to send back cores and even harder to find used ones to use as cores.