1. ## calculating MPG from OBD-II readins

Hi,

In a seperate thread (started in 2006 so I started a new one as the other is probably ignored by now: http://www.mp3car.com/engine-managem...from-obd2.html) I read the following:

MPG = (14.7 * 6.17 * 454 * VSS * 0.621371) / (3600 * MAF / 100)
MPG = 710.7 * VSS / MAF

What I now wonder is: is this calculation for MPG for the average VSS and MAF in an hour?
E.g. if I have the average MAF value for 12.8 seconds and average VSS in that interval as well, should I then use:

MPG = (14.7 * 6.17 * 454 * VSS * 0.621371) / (12.8 * MAF / 100)

2. This is "instant" mpg. It's not an average over 12.8s (or however fast your reading). It's a snapshot in time.

3. Originally Posted by tripzero
This is "instant" mpg. It's not an average over 12.8s (or however fast your reading). It's a snapshot in time.
Ah! Ok. That 3600 (in 3600 * maf etc.) got me confused.
Thanks

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