Calibrating MPG on OBC E36

[HarryH]

Morning,
I have looked on the net ,but cant find anything specific regarding MPG reseting on the E36

It seems to be stuck at the 20mpg mark,and doesn't change
when i hit the reset button, it moves about a bit, but soon settles down to roughly the same thing

any tips?

[Shropshiremike]

HarryH said:

Morning,
I have looked on the net ,but cant find anything specific regarding MPG reseting on the E36

It seems to be stuck at the 20mpg mark,and doesn't change
when i hit the reset button, it moves about a bit, but soon settles down to roughly the same thing

any tips?

What does your own calculations of tank re-brimming indicate in comparison? i.e. if you fill the tank, see the mileage and then see how many miles you have done when you next brim the tank, what do you work it out as? You need to do that I'd suggest for at least 3 tankfuls to get an idea of how much the computer mpg differs from actual mpg ( if at all ) before you start entering correction factors into the OBC

[HarryH]

will do
i think i get about 250-300 mpg per tank
What bugs me more though, is that when i am trundling along a dual carriageway, i see no movement in the obc figures


thanks for the reply

[Shropshiremike]

HarryH said:

will do
i think i get about 250-300 mpg per tank
What bugs me more though, is that when i am trundling along a dual carriageway, i see no movement in the obc figures


thanks for the reply

Harry, do you reset the OBC every time you fill up? Otherwise I suspect it's calculating your mpg since the dawn of your car and you won't see any small variations as there isn't an 'instant' mpg feature. You should have 2 mpg calculators. I use one for the current tankful and the other for a longer term average. If you get the current one on the OBC screen and reset it when you have filled the tank you will get an idea of what the OBC calculates you are getting

[HarryH]

sometimes i reset, sometimes i dont
i reset it a few days back,when i filled it up, and it started at 80mpg!!!,then gradually went down and down, it went down to 17mpg, now its creeped up to 21mpg, and i suspect its going to stop where it normally does,at about 22 ish

I think i am getting what i should from the tank,given what car it is (250miles per tank), but on a long straight, i dont see the 30+mpg others talk about

[Ti22]

You can recalibrate the MPG function if it's off..

calculate the mpg, then divide the figure you got by the one the OBC got then multiply by 1000... enter this number in OBC function 20 as this link explains..

it's a bit fiddly, but over time you can get it spot on!

http://www.bimmerinfo.com/E36_OBC_tricks.htm

James

p.s. the instrument tests are good fun too!