Alright, I'll admit it, I am not the most knowledgeable person about cars and car mechanics, but I have noticed something that bothers me about my 2002 MCS. First of all, when I fill up the gas tank, my OBC reads that I have 406 miles to go on that tank of gas. However, I am barely getting 300 miles on one tank. Anyone know of a possible explanation. I do have the stumble and it was suggested that maybe my 17" wheels were throwing the computer off. Also, for example, if I am on the interstate and I clear the average speed gauge on the OBC it will read about 70 MPH even though I am going a steady 75 MPH on the giant center mounted speedometer. Shouldn't these two match up if the OBC was cleared and the needle has not moved? Well, some of you are probably saying, "Man this guy's an idiot, he has no idea of what he is talking about". But I would like just a tad of input on this issue, even if it is a reference to a previous thread. Sorry for the long post and Thanks so much!

 

Um, I'm not sure about the 1st issue, but the 2nd I think I could help with. I believe you need to reset the computer. Once in the average speed mode, hold the computer button until the reading goes blank. Then it will give up to date read outs. I you don't reset it from when you were going 75mph, the computer takes into account all speeds from when you started the car. Everything from starts and stops to the lower speeds you were going until you got on the freeway.

 

This was covered in a recent thread
Hope this helps.
and an older thread OBC
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Waiting to motor since 01/05/03

 

Thanks for the help, but that is exactly what I am doing when I reset the computer going 75. sorry, I didn't explain that very well.

 

the OBC's "miles to empty" is just a computer estimate. As you drive, you'll see that the closer you get to the end of the tank, the more accurate it will be (usually). It best used as just a rough guide, and not precise instrument. However, the average speed thing is more accurate than the big analog speedo. This is because BMW offsets the speedometer to error on the high side, usually pretty high, as in 8%ish. I've also heard that the MINI big speedo is 5mph high regardless of speed, but in any case you know it reads on the high side. The digital readout is pretty accurate because it's less filtered info from the wheel-speed sensors, not padded like the analog speedo.

whew, I hope that makes a shred of sense, back to bed I go

 

THanks everyone so much. I hope you get a good nights rest ryephile. I know that I will sleep easier knowing this about my MINI. Just kiddin'!!

 

Another thing to understand about the speedo is that it reads roughly 5mph faster than actual speed. This starts to happen around the time you hit 50mph. From what I understand, BMWs are pretty guilty of this.

 

Take a run for about 50kms down the freeway and the range to empty will increase dramatically. Get stuck in more city driving and it will go down on the same tank of fuel...