Onboard Computer inaccurate MPG

[dangermouse]

Hi all,

I believe there is a way to access hidden menus in the OBC to correct inaccurate reading on the average MPG. Unfortunately all the results I have got from Google give a link that is broken. Does anybody know how to do this please?
My Z4 is lying to me to the tune of 4 or 5 MPG although the mileometer, fuel gauge, miles to empty and speedo are all accurate as far as I can test them
I could ignore it, but then I can't 'cos once I get a bee in my bonnet..........

 

[hard top]

Sorry, I have not got an OBC in my 96 Z3 and the chap that could probably tell you is away for a week.
There might be someone else on here though that might know?

 

[t-tony]

Same here, only mines 2000 2.0 Auto without OBC. So sorry no help but at least we're taking notice.

Tony.

 

[roadvoyager1]

This article is for a 1997 E36 OBC but may give some information that is of use. Seems it has more functions than I have on my 1999 Z3.

http://www.bmwe36blog.com/bmw-on-board-computer-obd-secrets.html

Let us know how you get on.

 

[dangermouse]

Thanks, will do

 

[GazHyde]

My 2003 3.0 Auto had the most accurate OBC on any car I have owned. Was always within 1-2 mpg of what I worked out manually.

 

[dangermouse]

Funny enough this is the first BMW I've had with an inaccurate reading. I suspect it might be due to a change from the original wheels

 

[t-tony]

If the rolling circumference of the new wheels and tyres is the same as the original set it shouldnt make a difference. You can find what the car originally had by looking at a thread by GazHyde on this subject.

Tony.

 

[dangermouse]

This article is for a 1997 E36 OBC but may give some information that is of use. Seems it has more functions than I have on my 1999 Z3.

http://www.bmwe36blog.com/bmw-on-board-computer-obd-secrets.html

Let us know how you get on.

Hi Tony, unfortunately my OBC isn't the same as the E36 and doesn't have the buttons described in the article. Hopefully the info about the different codes will be useful if someone can tell me how to get into them on the Z4