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How much reserve fuel left after computer reads 0

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by RobMorris, Mar 27, 2013.

  1. RobMorris

    RobMorris Member

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    Chaps

    Im trying to figure out my MPG.
    After brimming I managed 550 miles to 0 miles remaining on the computer.
    There must be a reserve - anyone know how many litres it is?

    Cheers
     
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  3. Legacy87

    Legacy87 Member

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    Not sure on Litres but a fair bit, In my short experience with the B6's in the past 2 months ive had a 1.9 TDI and a 2.5 TDI Quattro and both of them have had horrid electrics and stupidly erratic computers/fuel needles.
     
  4. Az

    Az Hard slammed!

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    I drive around for about 3 days on 0! But, I wouldn't advise this to anyone else, I can because I know that I too have that irratic fuel needle which can show 70 miles on the range one minute, then drop to 30 miles, then 10, then 0, all in the space of 1 minute and about 1 mile! It's been like it since I first bought the car back in July 2010 so I've just leant to live with it. I spoke to Russell Automotive (Audi VW specialists) about it and they said it could be one of two things, either the gauge / dis needs recalibrating via VCDS which is the cheapest of the two by far, think they quoted me about £60-£70 for that, or it's a knackered fuel gauge sender unit. They're are 2 fuel gauge senders in the tank, 1 either side of the tank as it has the hump in the middle to clear the proshaft/diff, that they quoted me around £200+ for.
     
  5. Audi Doodah

    Audi Doodah Active Member

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    The best way to calculate mpg is to keep your fuel receipt and note your mileage on it when you fill up. That way, after a couple of fill ups, you have a record of the amount of fuel used and mileage traveled.

    Then to calculate mpg:

    Multiply the amount of fuel you put in in litres by 0.22 (this gives you fuel amount in UK gallons).
    Now divide your mileage traveled by fuel used (in gallons) and there's you mpg.

    It's the best way as DIS is notoriously inaccurate
     
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  6. stu_m

    stu_m Well-Known Member
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    this is all good and well but he is asking how much fuel is left in the tank when your DIS reads zero!

    to answer the question its anyone's guess I have had it reading zero a couple of times and fill up with about 60 - 65 litres and thats as much as I can squeeze in before it overflows!
     
  7. Audi Doodah

    Audi Doodah Active Member

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    But his opening line is "I'm trying to figure out my mpg" :yes:

    In my case, when I fill up when in the red, I get 65 litres in my 70 litre tank. Dis normally says 30-40 miles to go which would account for the 5 litres left in there so 0 to go would be any empty tank.
     
  8. AndyMac

    AndyMac Moderator
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    Zero on the range means you have less than 5 miles left, I've found this to be pretty damn accurate, but as said it is irrelevant when calculating mpg. Fill it up, do 200-300 miles then fill it up again to see how much fuel you used doing that mileage - it's not exactly complicated!
     
  9. stu_m

    stu_m Well-Known Member
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    hmmmmm so it does got me there lol
     
  10. PetrolDave

    PetrolDave Well-Known Member

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    I've been in a friends B7 RS4 while he drove 25 miles with the DIS showing the range as zero...
     
  11. AndyMac

    AndyMac Moderator
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    He's obviously an idiot
     
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  12. Legacy87

    Legacy87 Member

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    I wouldn't say so, The instruments on the B6 are about as much use as a chocolate teapot, they are completely useless as far as i can see, theres no clear instructions on how to re-calibrate them, on my 2.5 TDI Quattro I can put £20 Diesel in, DIS reads either 110 Miles, 150 Miles or 135 Miles. I actually get about 60 before it says "0" then i can openly drive for 2-3 days (30-40 mile?).

    It 100% definitely does more than 5 Miles, to my parents and back is an 18 mile trip and i do it daily, My car hit zero yesterday and has done the round trip twice since, just filled up tonight on the way home because i didnt want to risk running out. Now after adding £20 fuel its on 135 Miles.
     
  13. Audi Doodah

    Audi Doodah Active Member

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    I sense a lot of anger towards B6 instrument clusters, Legacy87!?!? :gun2:
     
  14. Az

    Az Hard slammed!

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    Lol, sounds about right. Gotta love em tho! :)
     
  15. Legacy87

    Legacy87 Member

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    Haha no i just thought "He's obviously an Idiot" was abit harsh considering the well known issues with the DIS.
    Some people have the luxury of a working fuel needle... i do not.... in either of my TDI B6's!!!
     
  16. Audi Doodah

    Audi Doodah Active Member

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    Ha, maybe envy then!? :lmfao:

    Why not just have one of those green "reserve" tanks in the boot with 5 litres of diesel in it? When your car konks out, apply reserve tank, drive to nearest garage!
     
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  17. crazy88

    crazy88 Loving the anonymity

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    Or just figure out how much you generally do on a full tank and whenever you approach that figure just fill up.

    On a side note, I don't actually find my gauges to be bad at all.
     
  18. deano1978

    deano1978 different gear

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    Fuel gauge is a pain,up,down,its just inconsistant!
    For the record. In the middle of a journey,my dis read 0 mile, im 40 milez from home.
    Made it anyway :O phew.
    I filled up to brim,think i got 69 litres.
    Now that was close.
    I know its not good running that near to empty. No choice in that instance.
     
  19. RobMorris

    RobMorris Member

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    Thanks all for imput. There is definitely a reserve after 0.
    More than 5 miles I think 99% will agree.
    Shame no one knows the actual answer.
     
  20. quattrojames

    quattrojames Moderator
    Staff Member Moderator Audi Avant Owner Group Audi A6

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    Nor me, my fuel gauge is pretty consistent.

    I generally run the DTE to 20-30 miles and rarely get more than 60l into a 66l (off the top of my head?) tank. I've run it doen to zero before but I don't usually see much point in doing so.

    That seems a little dramatic! after 5 years on this forum I've never read a statement like that before, granted the DTE gauges vary a bit but that's about it.

    How many cars come with instructions on how to recalibrate the fuel gauge/mpg reading?!

    In the DIY guides sticky is this, which will tell you exactly how to do it:

    http://www.audi-sport.net/vb/audi-s...adjusting-mpg-dis-shouldnt-effect-fuling.html
     
  21. stu_m

    stu_m Well-Known Member
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    As above I have never had a problem with my gauges they work really well and are consistent

    Also my DIS is accurate to .2 mpg yes thats point 2!! I have adjusted it with VCDS and every time I fill up I put all the details in to an app to record MPG and my DIS is always .2 out

    the miles to empty can fluctuate but it depends on how you are driving and it will always drop first thing in a morning with a cold engine
     
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  23. PetrolDave

    PetrolDave Well-Known Member

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    +1

    Drive the car like you stole it, then drive it like a Granny and watch the miles left INCREASE for quite a long time.

    It estimates the miles left by calculating the mpg over the last 20 miles or so and using that to work out how many miles left you have. Since it uses a short term mpg figure it's not going to be either accurate or consistent over a ahole tank of fuel - unless you always drive the same way and average the same mpg. Which means that the miles left after it shows 0 isn't an exact figure, it will vary between car, driver and recent driving style.
     
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  24. Andie0

    Andie0 Member

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    When my 1.8t shows 0 miles it means it ran out last night 2 mintues from shell garage... Pissseddd now my dis isnt calculating remaining mileage do i need to reset this using vag com?
     
  25. AndyMac

    AndyMac Moderator
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    I meant he's a bit dumb to deliberately let a high performance car drag all the shyte at the bottom of his fuel tank through the fuel system! Nothing to do with the accuracy of the DIS.
     
  26. VagCabby

    VagCabby Active Member

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    I have no issues with my fuel gauge or my dis, usually when I fill up and have covered 20 miles the reading on my dis is pretty dam accurate to the actual mileage I get out of the tank. Today I filled up, 10 miles showing on the dis, brimmed the tank and got 67 litres into it.
     
  27. AndyMac

    AndyMac Moderator
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    Same here. As long as its not showing a 20 mile range and running out of fuel what's the problem?
     
  28. PetrolDave

    PetrolDave Well-Known Member

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    +1

    I hate letting my fuel gauge go below 1/4 tank - only done it once in 35+ years of car ownership.
     
  29. 666markyboy

    666markyboy Well-Known Member

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    I too find my miles to empty to be extremely acurate.... to the point where cruising on a motorway you can see it recalculate as you go up and down gradients at the same speed... and as for dropping in the morning ... dont forget when you were last driving the car it was hot and was being fueled for a hot engine... when you turn it on in the morning the engine is cold so has to be fueled accordingly, a bit like pulling the choke out on an old car ( showing my age there )
     
  30. JimC64

    JimC64 Active Member

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    Does no one here use Fuelly at all?
    Just a thought as an add on.............something I've been doing for a little while now......extremely accurate too

    Fuelly | Share and Compare Your MPG

    After a recent long journey my DIS showed 39mpg, when I filled up with the trip showing zero miles I could only get around 67.4 litres in after brimming the tank?
    Inputting the info to my fuelly account registered as something like 39.6mpg so pretty much bang on

    My A6 has had 750 miles from one tank, I worked out around 9.87 litres left in the tank at an mpg of 48.4 or similar I calculated I could achieve around another 105 miles, giving a total of 855 miles!

    After refuelling the DIS told me if I drove the same route i nthe same manner I could expect 915 miles till empty......not bad.

    Having checked more than a few times I estimate the reserve to be around 10 litres, pretty much inline with what most of us think I guess?
    However, if you've been hareing around and are getting approx 32mpg your range will be differet than if you are achieving 48mpg obviously.

    Hope that makes sense?

    Check out Fuelly.............its a pretty good tool for keeping track of your mileage, expenditure and what your car is costing to run on fuel.

    All good really....
     
  31. benjie

    benjie Well-Known Member

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    When the dis shows 0, along with the needle, it's not empty. It's on R. As in Reserve I assume? Sorry if I'm pointing out the obvious. I got down to 5miles left last week - first time ever. Put 64L in and (along with the Nectar points) that was enough excitement for me. I'm just not hard core enough.


    I find my DIS to be accurate to 1-2mpg based on calculations I make once every 6months or so (when I'm bored).

    I too like the way the car turns itself into a mini-refinery when you're cruising along... If the miles till empty is going up then surely that's the only answer?!
     
  32. GeoffDunk

    GeoffDunk Well-Known Member

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    One of the fists things I do when I get a new motor is test this limit. I did this with my 1.9 TDI passat and proved I could get 50 miles after it went to 0, so I knew if I drove it like miss daisy I could manage to get home when there was no fuel avaialbe.

    The S4 will do 22 miles after 0, again, I know where I stnd on that one too.
     
  33. JimC64

    JimC64 Active Member

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    See some of the results I've managed to achieve below....

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    For the life of me I can't remember where, but in one of them after fuelling with the DIS showing ZERO miles I found I still had around 9.1 litres left and at the mpg I was getting I could get another 100+ miles potentially not that I'd like to experiment....lol
     
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  34. AlexGSi2000

    AlexGSi2000 Well-Known Member
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    To be honest, I usually put fuel in when the guage tells me to do so.
    Never tried running the risk of running out - whats the point? - Plus I would need to bleed the system if it ran out.

    I have found the fuel guage / trip computer adjusts to your driving style from the previous few minutes.
    I have driven quite harsh on country roads to find the needle drop - then jump on an A road and sit at 65mph the gauge rises again slightly.
     

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