Alright - so here is the current status:
We have 4 options:
I) Nothing: We don't do anything and rely on BMW and Bosch to keep re-building the old MAFs. It's somewhat costly but the cars will drive.
Cost: 0€ + parts prices from BMW
II) Digital Conversion: It's the thing I've talked about. Conversion electronics + modern MAFs (we can guarantee 4k hours of operation (capacitor) up to 140°C).
Cost per side (x2):
250€: Electronics per piece. The main cost is soldering time (somebody needs to do that manually)
?€: 3D printed Connector (but probalby very low once a model is made)
~300€: Modern MAF (off the shelf)
=> About 1100€ for a car
III) Analogue conversion
If the conversion characteristic does not need to be very accurate, we can just shift output voltage using cheap analogue electronics.
I can only recommend that if the characteristics are only shifted. I need to check.
Analogue circuit: ~100€ (only few parts so very low soldering time)
Connector: ~?€
Modern MAF: ~300€
==> About 800€ for a car
IV) Full digital and programmable
This is the most fun and not more expensive than option II) because most parts are off the shelf. Via bluetooth you can observe the measured values, temperature in the engine bay and so forth. You could programm different characteristics on the fly...
BUT!: Temperature resistance is only guaranteed up to 80°C.I don't think this works in the engine compartment - I assume that we easily reach temperatures of 90°C on a hot day in a traffic jam.Still, I haven't really measured it. I might upload the video of all of that stuff and post a link..
What do you think? I, personally, would still recomment option I) or II). I have a guy that can 3D print it, but he needs a model.
Also I prefer II) over III) because the overall price does not really differ and we can fully program it.