OBC Range display

[William]

Can anyone advise how this works? Mine is showing 209 miles when the fuel guage is showing the red light. Me thinks something is not right

[Cloggy Saint]

Have you calibrated the remaining fuel in tank? If not you need to press the 1000 (or is it 100?) and 1 buttons simultaneously to find out how much fuel is in the tank. When you fill up turn the screw behind the cap at the bottom left of the obc unit until it reads whatever your tank capacity is. The range should be more or less accurate then. Hope this helps.

[gcorky]

1000 and 1 buttons for fuel remaining

[William]

thanks guys I haven't done any calibrating so Im sure this will solve it. datouring, I can't picture a cap in the bottom left of the OBC (or screw) can you elaborate at all, before I go out and check it out.

thanks

[Cloggy Saint]

It's a kind of bung with a very small hole in the centre, in the bottom left corner of the unit. stick a needle in the hole and wiggle and the bung will come out.

[William]

thanks datourer, found it and got it out. I have just filled up and put 54l in to fill it to the brim. I drove home about 1.5 miles and have just done the check. When I hold 1000 and 1 it says 55.5l. I thought my tank held 65?? (its a 325i) So I turned the screw and at one extent it read 54.5, and the other extent 55.5, should I only be able to get one turn on the screw? I'm a bit lost

thanks for being patient

[Cloggy Saint]

err, not too much of an expert on this. Do you have the correct coding plug?

[William]

god knows, it says +360 which is about right at the moment, but im fairly sure that after another 100 miles or so it will still be saying well over 300. What are you doing when you turn that little screw? Does pressing 1000 and 1 tell you how much fuel is in the tank, or how much fuel the tank will take?

[gcorky]

55 for 4 potters and 62 for 6ers

[Cloggy Saint]

Pressing 1000 and 1 tells you how much fuel is in the tank. My obc tells me i can do + 550 km on a full tank which can't be done. It does get more realistic as the tank empties but i've never tested it's true accuracy. The remaining fuel feature does seem pretty accurate & usually ties in with what the fuel gauge reads.

[gcorky]

so if you put say 60 litres in press 1000 and 1 together ,should tell you 60l ,if this is the case assuming you have correct code plug(search theres a table on here somewhere)range will be correct

[Cloggy Saint]

That's the theory, although i don't know if the range is calculated by how the car is being driven at the time or a pre-set mpg figure. Does it take into account a poorly set up/worn engine?

[Jackle]

I think there is a limit as to how much the fuel level gauge in the tank can read the level, once you get over a certain point it just says the tank is full. Thats what the + sign in front of the range readout means.
I found the best way to calibrate the OBC tank readout was to put say 10 litres in and then adjust the screw until it looked about right (ie gone up by 10 litres), and just do this a few times tweaking it until it accurately showed what you'd put in the tank at each fill-up.
When the tank is full right up it will always show 55.5l because it can't measure more than that in the tank...

[William]

Jackle, if I understand you right this is what you mean:

You have 30l in the tank as stated by the OBC (1 + 1000)

You add 10l of fuel as stated by the petrol pump

You then query the OBC again and adjust screw until it says 40l.

Am I correct or have I missed the point somewhere??

THanks

[Jackle]

Yeah something like that, then next time you put a tenner in, do it with a different starting amount in the tank and adjust the screw again. Once you've done that a few times you should find that you don't need to adjust the screw and it should be fairly accurate. It worked for me anyway