Fuel Consomption from OBD-II values

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Chris - 05 Oct 2006 17:12 GMT

Is there any way (formula) to calculate the fuel consumption (e.g.
L/100 KM or Gal/Mil) from values read from OBD-II interface?

I think next values could be taken into consideration to compute the
fuel consumption, but I don't know how exactly to interpret the result
of them:

Short Term Fuel Trim
Long Term Fuel Trim
Mass Air Flow
Fuel Pressure
Accelerator Pedal Position
Throttle Position
RPM

Chris

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Carguy - 05 Oct 2006 20:13 GMT

> Is there any way (formula) to calculate the fuel consumption?

I don't think it's possible, there are some programs that act like a
trim computer (showing instant MPG data, average fuel consumption,
etc.) but the actual fuel consumption will be different from what the
computer may show.
I just do this a simple way:
1. Note the reading of the fuel gauge when it's at easy to see exact
position (e.g exactly an 1/4 tank mark).
2. Reset the trip odometer to zero
3. Fill up the gas tank (it's easier if you fill up with even number of
gallons or liters, e.g 30 liters.
4. Drive and once the fuel gauge will show the position you noted when
you zeroed the odometer - check how many miles you drove.
So suppose you filled 30 liters and drove 250KM before the gauage shows
the same reading.
So you got 100x30/250=12L/100km

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TeGGeR® - 05 Oct 2006 22:32 GMT

"Chris" <criro1999@gmail.com> wrote in news:1160064779.892720.143910
@i3g2000cwc.googlegroups.com:

> Is there any way (formula) to calculate the fuel consumption (e.g.
> L/100 KM or Gal/Mil) from values read from OBD-II interface?
[quoted text clipped - 10 lines]
> Throttle Position
> RPM

I seem to recall seeing a laptop-based OBD-II diag system that was capable
of the sort of number-crunching you need to do. I don't seem to have
recorded the maker, though.

Laptop solutions are software-based, with an adapter cable that conects the
OBD-II DLC port and a USB port on your laptop.

Signature

TeGGeR®

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/

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BennyB - 06 Oct 2006 21:50 GMT

Here is a software for OBDII to do what you are talking about.
http://obdiitools.gdatabase.com/

I just do the old fashon way. When I pump gas I reset my milage or
write down the current milage and pump the tank full. That way next
time I pump I record that amount and divid it into the milage recorded
and get an average MPG.

Regards,

BennyB

> "Chris" <criro1999@gmail.com> wrote in news:1160064779.892720.143910
> @i3g2000cwc.googlegroups.com:
[quoted text clipped - 26 lines]
> The Unofficial Honda/Acura FAQ
> www.tegger.com/hondafaq/

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Gordon McGrew - 08 Oct 2006 15:34 GMT

>"Chris" <criro1999@gmail.com> wrote in news:1160064779.892720.143910
>@i3g2000cwc.googlegroups.com:
[quoted text clipped - 20 lines]
>Laptop solutions are software-based, with an adapter cable that conects the
>OBD-II DLC port and a USB port on your laptop.

Or you can buy one of these:

http://www.scangauge.com/

I bought the older and much clunkier first generation model. It works
very well and does all of above and more. ON caveat: fuel
consumption and related values (like miles to empty) are accurate only
to within 10% and perhaps more. Good for determining how speed
affects your fuel consumption but it doesn't replace actual fuel
consumption measurements made at the pump and I wouldn't use it to
decide whether I could make it to the next station.

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TeGGeR® - 09 Oct 2006 01:02 GMT

>>Laptop solutions are software-based, with an adapter cable that
>>conects the OBD-II DLC port and a USB port on your laptop.
>
> Or you can buy one of these:
>
> http://www.scangauge.com/

I like these people already! Check out the photo on the home page.
129 mph! 5174rpm! Somebody's having some cheeky fun here!

Signature

TeGGeR®

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/

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