Reply With Quoteif you have the link to the instructions on how to "unlock" the OBC...the formula for gas consumption is given in the TEST for gas consumption. You can search the archives here for the instructions...or go to Bruno's web site.
3 Grand Master
::.. How is the avg MPG L/100K calculated in the OBC?
Thanks to ArtemLepilov's post, I remember what I wanted to ask for some time...
How is the fuel economy calculated in the OBC? How many data points does it store, or perhaps what type of formula is used to calculate a continually running average?
Major Contributor
if you have the link to the instructions on how to "unlock" the OBC...the formula for gas consumption is given in the TEST for gas consumption. You can search the archives here for the instructions...or go to Bruno's web site.
Last edited by Qsilver7; 10-19-2005 at 05:58 PM.
Q
95 525iT / 97 740iL
3 Grand Master
On demand consumption is test 2 I believe... or test 8. One's speed, one is economy... so are you saying the formula is in the OBC display or on a site on how to access the 'unlocked' OBC?Originally Posted by Qsilver7
Major Contributor
here it is...if you go down to the bottom of the page...(#2) there is a footnote on how to calibrate the avg fuel consumption...from the instructions given on how to recalibrate, you can extrapolate how the OBC formulates the average: http://home.iae.nl/users/bts/obc.htm
Q
95 525iT / 97 740iL
3 Grand Master
Okay I'll bite. Huh? The wheels go round, the horn goes honk.
Major Contributor
In basic terms...it's calculating the mileage and gallons of gas being consumed.
From the web site:
*2
The average fuel consumption value can be calibrated from the OBC. Function 20 is used for this.
* Fill the fuel tank to the maximum.
* Reset the day trip counter.
* Run the fuel tank nearly empty and fill the fuel tank again to the maximum.
This will give you the fuel consumption.
New Correction Value = Old Correction Value * OBC Fuel consumption (in MPG or l/100Km) / Actual Fuel Consumption (in MPG or l/100Km)
Q
95 525iT / 97 740iL
3 Grand Master
Right right... so my question, updated is...
There are two OBC counters. I reset ONE of the two at every fill. How is the 'older' one being contantly calculated (and different of course) from the newer reset value?
Does this question make sense to anyone other than me, or am I delusional? Sorry for heckling if it seems so.
Big, Big Time Poster
Miles per gallon is calculated by summing the total miles and dividing by the total gallons consumed since the last reset. I believe that in order to keep Consum1 separate from Consum2, the values are simply stored in separate registers.
There are probably some constraints to prevent displaying a constantly changing average. My OBC won't change the reading until the change is greater then .3 MPG. If it hasn't changed for some period of time, then it will display smaller changes.
Paul Shovestul
Last edited by Bellicose Right Winger; 10-19-2005 at 07:45 PM.
.....Got to keep the loonies on the paath.
2 Grand Master
The older one is being calculated by the fuel consumed to get the miles you've travelled since you last reset it.
Ralph Mendoza Jr. - Long Beach, CA
2 Grand Master
Mine jumps or declines in values of .1 or .2
Ralph Mendoza Jr. - Long Beach, CA
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