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  • Cruise Whore
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  • Member For: 19y 9m 10d
  • Gender: Male
  • Location: Melbourne

Been a little while since I got back from Adelaide and average fuel economy is still showing as 10.9 l / 100 km.  I reckon the way fuel consumption is calculated is the cause for my high readings earlier and my lower than expected readings right now.  It would be good to know how its actually calculated if anyone in the know knows ...

  • Manual mode ________________________ All day, erryday
  • Donating Members
  • Member For: 17y 5m 21d
  • Gender: Male
  • Location: Probably above atmospheric pressure

I have wondered about the length of time it keeps readings for when calculating the average.  If you never reset it does it have the ability to calculate everything from day dot?  Or does it only keep results for say 100 hours?  More likely it keeps a truncated average at X distance and changes it as you go I guess.

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  • less WHY; more WOT
  • Site Developer
  • Member For: 17y 1m 5d
  • Gender: Male
  • Location: Melbourne

edit: it would just average the latest two readings at each calculation time, I would imagine, to save potential calculation time problems. Now that I think about it, they'd probably go to a max stored array calculation (probably int8 or int16 sized, depending on architecture) and just use a stack style mechanism to push the oldest record out and replace the latest record in the array and just average across that.

 

The FG polls the information much faster than the BA, though, so the numbers might be different so that it's not calculating too many numbers too often.

Edited by k31th
  • WOT?
  • Moderating Team
  • Member For: 12y 2m 20d
  • Gender: Male
  • Location: Frankston, 3199

https://www.google.com.au/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=how+do+car+computers+calculate+mpg&*

 

Pen, paper and odometer vs pump (or an app) over a long term will be the only one really worth worrying about or trusting.

 

Especially if your cars modded

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  • less WHY; more WOT
  • Site Developer
  • Member For: 17y 1m 5d
  • Gender: Male
  • Location: Melbourne

should just merge this thread into the fuel consumption thread, eh? :stirthepot:

  • Bronze Donating Members
  • Member For: 11y 1m 18d

It depends on what the tuner did. Usually with a high flow cat they dont work efficently & the second sensor will pick this up, log a code & turn the CEL on.Being a stock cat the sensor may have been left operating. I suppose the easiest way to check is crawl under the car & dissconect the plug then take it for adrive & see if the light comes on. Oxygen sensors are not really meant to last the life of the vehicl, at tech they said to veiw them as a long term spark plug

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