Hey guys, my first post here, but I've been lurking for awhile.
I just noticed that the ProScan 5.3 software has added a fuel economy feature. Not sure how they ended up calculating MPG, but I'll have to see how accurate it is. I just ordered an ELM327 module so I'll be able to test this out in a week or so. Will report back.
Okay, so I got my ELM327 shipped from Hong Kong earlier this week. It cost just over $30 from eBay.
I installed the USB drivers and software on an old P3 laptop. The program runs fine at that speed and there was no problem communicating with the OBDII port.
I quickly flipped through all the functions in the program - lots of interesting stuff like O2 sensor readings, fuel trim, etc. But I was only really interested in the fuel economy function - and in that, I was sorely disappointed. Everything worked except for this feature! The page would log the distance traveled, but the fuel usage stays at zero and the MPG is infinite.
So I did a bit more research and found out that my car (98 Corolla) doesn't have an MAF sensor. I'm assuming the program is basing fuel usage from that sensor data. I plugged it in to a friend's Ford Escape and Protege5, and both of them showed instantaneous fuel economy.
My question now is whether anyone is using a Scangauge with an 8th gen Corolla (specifically 1998)? I think the ProScan software can probably be updated to work with my car, but I'm not holding my breath for anything soon. There seems to be quite a number of complaints on the support section of their website.
So is it a total waste of money? I don't think so. The ability to read and clear the CEL will probably come in useful sometime. Also, other stats like the short and long term fuel trim can be telling of potential problems.
Maf should be able to be calculated at least reasonably closely from iat, map and rpm, so doing an MPG gauge for your car shouldn't be impossible.
Another possibility is calculating a BSFC map from data you have collected with your ELM327. Using fuel flow (air), rpm, map, speed and open loop signals it should be possible to figure out the instantaneous horsepower at each moment (proportional to acceleration) and thus the instantaneous BSFC.
I'm waiting for my own ELM327 and I'll know more when it arrives.