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Originally Posted by MFGJR
My understanding re: OBD II is that the manufacturers are required to make cetain data, in a prescribed format, available through that port. (Remember, its primarily an emissions diagnostic tool.) Some manufacturers push additional information through it, beyond the Federally-mandated data, but its a free-for-all as to what additional data and how it's formatted, and it varies from manufacturer to manufacturer as they use it for proprietary purposes..
From my research when i was planning to get a TraqMate, the Porsche guys can source RPM data from their OBD II ports, but E46 M3 owbers can't get a reliable signal there--it works at idle but is inaccurate once revs increase. So, the conventional wisdom for M3s and TraqMates is that you must use TM's ECU Bridge, feeding it via the ECU's analog coil output signal. So, when James Clay and jamie Millhiser at BimmerWorld said OBD II was unreliable for BMWs and to use the CAN option, it made sense.
All the data that Solo logs is continuously passed by the ECU over the CAN bus, as coded packets of information. AiM decoded BMW's signal into a bunch of useable information. I don't think anyone esle has done that yet for data logging purposes.
I'd suggest calling Jamie at BimmerWorld to discuss the options, though, as I'm pretty much out of my league already.
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Sounds like you did your homework, tapping into the ECU doesn't seem too bad and from my brief look into the AIM solo DL you can get more data via the CAN bus then you do via OBDII port. This fits with what you touch on in your last post.
Keep this thread active, even if its just a conversation b/n the two of us!! HAHA
Is this your first experience with data acquisition or have you had experience with other products on the market?