Its really a big deal to do this,, like I said, it's taking a potentiometer reading and converting it in to a thermister reading..
AFMs measure air intake flow basically (and this is a very basic statement) but basically on a 1-100 type scale (i'm sure the actual numbers are very different..) A thermister measures temperature, and depending on the car and whichever other inputs there are, it reads the amount of airflow depending on temperature..
Now, in order to accomplish this, one must make a program (more specifically a series of algorithms) that will tell the computer "IF",,, "THEN".... I'm sure they have the programming done, or i would hope they do,, but working out the bugs on this type of system i would imagine could take years.. There was another m42 member that was looking in to this at one point and I believe he must have given up on it.. There's no real gains,,, maybe better throttle response, but that's about it.......
All in all, I really wouldn't expect this project to be done anytime soon.. they certainly shouldn't have taken pre-orders yet.. Good luck to all who have ordered it!! I hope you preordered for reasons that you've done research on, and not just because it's "cool", so someone TOLD you you'd get a shit ton of horsepower and torque... I think if you haven't done your homework, you're gonna be seriously dissappointed with the results... that's my .02 anyway......
While the differences between the sensors are great, the conversion is not all that difficult. If you have access to a flow-bench, accurate temperature meter, and a digital multimeter, you can get all the data you need to deal with the 2. Don't forget the all-important ideal gas law either.
I built my own MAF converter from scratch using a PIC microcontroller, a DAC and some other basic passive components to filter the signal. So far, I have about 10 months and 6000 miles on it, with no "hiccups." They took a different route, reprogramming the ECU. That is a LOT more work, but also necesary if you want to claim power gains. I will say it again...converting toa MAF will not give the M42 ANY more power. What their kit was was a MAF, combined with a performance chip. You would see the same dyno gains with JUST a Conforti chip.
MAF's DO improve throttle response and idle behavior. They also eliminate some odd transient effects saving marginal amounts of gas upon acceleration. I feel that these things were worth the trouble, but I am also a big nerd that loves this stuff. If I had to guess about the "driveability" issues thay were mentioning, I would venture to guess that they involve intake resonance. With the M42 having no intake overlap, and the MAF being extremely fast and sensitive, each intake pulse can be resolved. Between 2500-3000RPM, the intake system resonates badly, and without some digital and analog compensation, you get fuel cut. See the link below for why that is. For those in the know, it has to do with aliasing issues and the Motronic sampling below the required Nyquist frequency of the air flow/measurement system.
http://bmw.e30tuner.com/articles_mafcon.phpFor a rough primer on sampling signals and whatnot, check this out:
http://www.e30tuner.com/projects/aliasing.pdfJust got an e-mail from Miller. The M42 MAF Project has come to an end.
Miller Performance Ltd.
2001 Abbotsford Way
Abbotsford, BC
V2S 6Y5
Release May 29, 2007:
Dear Valued Customers,
Due to unforeseen complications with the M42 Mass air flow (MAF) conversion, Miller
Performance is deeply sorry to announce that M42 MAF Development will come to an
end. It is no longer profitable to pursue this MAF system. Unlike Miller Performance’s
other MAF system, the M42 will not be able to use the components that are normally
used in the generation of these systems. As well, the Air Flow Meter (AFM) is very
different from any other AFM Miller Performance has studied. The complications that
have risen from the M42 System make it impossible at this point in time to release a
product that holds to Miller Performance’s high standards. There were drivability issues
that surfaced over time as the ECU adapted. With over $6000 invested into the
development, Miller Performance has stated that it is too costly to continue. It will
however, in the future, reopen the research as there is a solution. But, because this
solution will take more time to develop, we can no longer keep our pre-release customers
waiting. We will be issuing FULL refunds to all who pre-purchased their M42 MAF
system.
Again, Miller Performance apologizes for any disappointment and we hope you
understand.
Miller Performance Staff – Public Relations
CC: Daniel J. Miller – President
CC: R. Brody Saari – Vice President
The AFM is not different than other ones. The voltage-flow curve is different than a non-M42 sensor, but so were the M20B27 and M20B25 ones. They all operated in the same manner. The M42 sounds like it is the only 4-cylinder they have really dealt with as far as a MAF conversion. As such, it has its own set of dynamic air flow issues. Doing this conversion with only a reprogrammed ECU chip would be a real pain without modifying any circuitry. I suppose they could have added some filters onto the sensor body, but I never saw any on there. Most M42'ers already have chips anyway, so this would have done nothing for power, which is what 99% of people want. Thus, they are quite right in saying it is unprofitable. That's why I kinda called off a production version of my unit.
