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I've been browsing the Focus FI forums for more info/ideas on boosting my Zetec. Instead of running larger MAF units, they are just using a Diablo MAFia. It's runs about $160 so it seems like it would be a nice alternative. It's got me wondering tho...

I always tought that once you maxed out your stock MAF, that was it. It only put out 0-5volts. Does the MAF actually put out more than 5volts when pushed farther than it's stock limits? ..and the MAFia is just scaling that voltage range to 0-5volts? A range that the PCM can understand.

How do you calibrate that to something like the SCT ProRace software? Is it just a guessing game as to what transfer function that you are running?


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I knew it. I found this data on the mafturburner website...

The default setting for the DIP switch is SW1 ââ?¬â?? SW4 ON. This will scale a MAF sensor output of 0-7Vdc to the full input range of the PCMââ?¬â?¢s A/D input of 0-5Vdc. This setting will only be used under the most extreme circumstances. If the unit is installed with the DIP switches in the default configuration and tuning changes are not made the car will be dangerously lean and may not run at all. As a general rule, do the LEAST amount of scaling possible for your application. Remember that the more you scale the MAF curve down, the more resolution you give up in the low-flow portion of the curve and that this may affect driveability.

It scales pretty severely also. Check out their settings...

Code:

Vin to Vout - Scalar Value - HP ('03 Cobra with stock 90mm MAF)
5V to 5V 1.0000000 545
5.5V to 5V 0.7635203 714
6V to 5V 0.5941677 918
6.5V to 5V 0.4714800 1156
7V to 5V 0.3804597 1433



This could all be done quite easily with an op-amp. Hmmmm...

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To continue thinking out loud, here's a chart but with the MAF.ia values and some that I've calculated...

Code:

Vin to Vout Adjustment Equivalent PR Equivalent Boost
5.0 V to 5V None 1.0 None
5.5V to 5V 24% or mult by 0.76 1.316 4.64psi
6.0V to 5V 41% or mult by 0.59 1.695 10.22psi
6.5V to 5V 53% or mult by 0.47 2.128 16.58psi
7.0V to 5V 62% or mult by 0.38 2.632 23.98psi
7.5V to 5V 70% or mult by 0.30 3.333 34.30psi



Sure as heck is enough headroom for any turbo setup. The only limiting factor would be the diameter of the MAF itself.

By using an op-amp you could have any multiplier that you want. Not the coarse 5 settings that the Mafia gives you. You could dial it in to the exact HP that you are making giving you the best resolution.

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So I'm guessing you have to use one of their special MAFs in order to get the 7 volt output scale, then you are rescaling it with electronics to fit back into the factory 0-5v scale?

Either way it sounds dumb as hell when you can just tune in any good factory maf from a lightning/cobra with a $325 xcal2.

ONLY in the case of a high performance 1000hp vehicle where they may not make a maf big enough to be capable of that kind of airflow would I think it would be worth attempting this, but then maybe I'd just go with an aftermarket management system using speed density or something.


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Originally posted by warmonger:
then maybe I'd just go with an aftermarket management system using speed density or something.





Ding ding ding.....AEM for example.


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Originally posted by warmonger:
So I'm guessing you have to use one of their special MAFs in order to get the 7 volt output scale, then you are rescaling it with electronics to fit back into the factory 0-5v scale?




Nope, no special MAF required. The stock MAF can put out over 5 volts. It's just that the PCM can't understand anything over 5 volts. The MAFia or Mafextender just scales the voltage down to the 0-5 volt range that the PCM can understand.

$150 for something that can make your stock MAF the size that you need and not waste resolution. Sounds pretty good to me.

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Originally posted by ButtonPuncher:
Originally posted by warmonger:
So I'm guessing you have to use one of their special MAFs in order to get the 7 volt output scale, then you are rescaling it with electronics to fit back into the factory 0-5v scale?




Nope, no special MAF required. The stock MAF can put out over 5 volts. It's just that the PCM can't understand anything over 5 volts. The MAFia or Mafextender just scales the voltage down to the 0-5 volt range that the PCM can understand.

$150 for something that can make your stock MAF the size that you need and not waste resolution. Sounds pretty good to me.

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WTF is going on!? You are attempting hacked tunning on an ATX/zetec!?!?


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Nope. I've just found an alternative to ditching the stock MAF and upgrading to a (more expensive and less accurate) Lightning or Mustang MAF.

I also have the SCT PRP and xcal2. I'm not hacking anything.

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Less accurate? Whatchyoutalkinbout Willis? If you have the the PRP there is zero reason to squeeze your stock maf to size. Not to mention if you are going to be increasing the CFM's to the point where the voltage is maxed you would benefit from the larger diameter maf.


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Originally posted by ButtonPuncher:
Nope. I've just found an alternative to ditching the stock MAF and upgrading to a (more expensive and less accurate) Lightning or Mustang MAF.

I also have the SCT PRP and xcal2. I'm not hacking anything.

BP




The lightning and mustang MAF's are no less accurate. Not sure where you got that idea from.


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