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I want to know how can i obtain the values of Fuel Consumption, Fuel Economy and other fuel related information from basic OBD-II parameters like Vehicle Speed, RPM, TPS etc. I have noticed that not many vehicles support Fuel related PIDs so i want to obtain these values from available parameter values.

EDIT: I referred this paper . Formula given here is quite simple but is not universal for all cars.

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OBD2 PID list You can see Wikipedia: But not all cars show fuel consuption. –  user5182 Jun 4 '14 at 7:38
I answered this question… –  Juann Strauss Jun 4 '14 at 8:45
Yes and no. Barometric pressure is measured by a MAF sensor, whereas manifold pressure is measured by a MAP sensor. They measure the same thing though. You'll have to interrogate both PID's and use the one that actually gives back data. Cars usually only have one of the two. Pro Tip: MAP sensors are slightly less accurate but will allow you to keep driving if a vacuum line bursts or you spring an intake leak. MAF sensors are more accurate but will leave you stranded if you lose vacuum or intake pressure. –  Juann Strauss Jun 4 '14 at 9:26
@JuannStrauss ... I have to disagree with your above statements. The MAF and MAP do not measure the same thing. The MAF measures the amount of air flowing through the intake tract. The MAP measures the difference between the ambient and intake air pressures. Every modern fuel injected engine I've seen has had a MAP sensor, while a lot have both sensors. I've not seen nor heard of a modern electronic fuel injected engine not having a MAP sensor. Both sensors are used to utilize a more complex fuel map to get better economy and performance. –  Paulster2 Jun 4 '14 at 10:52
Well, Rockauto sells one for the 2000 540 BMW ... Since you didn't specify year, I had to guess right in the middle. If it's because of the dual TB, I can see that. BMW is one of only a handful which run their V-engines that way. Does not negate my point though. –  Paulster2 Jun 6 '14 at 11:20

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