Michail

Hi

I'm looking at building a Megasquirt and I figure I want to use a MAF with it.

It seems then that I would need to know the flow/voltage curve for the MAF I am using.

I do however not see any references whatsoever at retail sites as to whether such data is supplied with the MAF? And searching on Bosch's site I find nothing either, I only find tables saying what MAF goes with which car - which is of no use to me.

So: how the heck do I obtain the technical specifications on a MAF?

If I order for example from Summit:
http://store.summitracing.com/partde...t=SUM-29006B-C
http://store.summitracing.com/partde...MS-M-12579-L54
Do they come with a chart showing the output voltage at different flow?

How do people really DO when they choose a MAF for an injection system?

Thanks for any help

tequilaboy

The MAF calibration curves are typically obtained from the ecm's bin file. In Ford tuning circles, this is commonly called the MAF transfer function.

Here's an example of the MAF calibration tables from my 88 corvette original ABTR bin:

Mass Air Flow Table #1

Volts gm/Sec
0.00 8.4
0.18 3.2
0.37 4.5
0.55 6.2
0.73 8.4
0.91 10.9
1.10 14.0
1.28 17.7
1.46 22.3


Mass Air Flow Table #2

Volts gm/Sec
1.46 22.3
1.55 25.0
1.65 27.6
1.74 30.6
1.83 33.8
1.92 37.1
2.01 40.7
2.10 44.5
2.19 47.7


Mass Air Flow Table #3

Volts gm/Sec
2.19 47.7
2.29 51.3
2.38 55.2
2.47 59.1
2.56 63.3
2.65 67.9
2.74 72.4
2.83 77.3
2.93 82.1


Mass Air Flow Table #4

Volts gm/Sec
2.93 82.1
3.02 87.4
3.11 92.6
3.20 98.4
3.29 104.2
3.38 110.5
3.47 116.8
3.57 124.7
3.66 134.2


Mass Air Flow Table #5

Volts gm/Sec
3.66 134
3.75 142
3.84 150
3.93 158
4.02 167
4.11 177
4.21 185
4.30 195
4.39 206


Mass Air Flow Table #6

Volts gm/Sec
4.39 207
4.43 213
4.48 219
4.53 226
4.57 233
4.62 240
4.66 248
4.71 255
4.75 255
4.80 255
4.85 255
4.89 255
4.94 255
4.98 255
5.03 255
5.07 255
5.12 255

I'm now using a Pmas HPX sensor which is an aftermarket Ford slot-style sensor which is installed in a unique housing, so I had to develop my own transfer function from scratch, basically by trial and error. Pmas has a calibration tool for this sensor that helps to generate the transfer function for various housing diameters or cross-sectional areas, but it was way off in my case.

Michail

Heh, that's cool.

Thing is, I have no .bin file to read since I am building an EFI for a carbureted engine, and none of the MAFs I find at etailers advertise any kind of calibration tool, method, or even tell if the thing comes with a paper with a curve on it. Most just write "Fits an Audi A8" or similar.

And if I have to guess the values by trial and error then it has no advantage over speed density configurations.