DP7657 Posted May 12, 2011 Share Posted May 12, 2011 This morning my fuel gauge dropped to the red section with the amber light to indicate 49 miles DTE. At lunch, after 5 miles of driving, it made its way back up to half way through the final quarter, reading 70 miles DTE. Are they all this inaccurate or do I have a magic 350Z which produces its own super unleaded? (I hope it's the latter...) Quote Link to comment Share on other sites More sharing options...
coldel Posted May 12, 2011 Share Posted May 12, 2011 Mine is up and down as well, the electronic measure is just as cranky. I can drive for about 50 miles and the electronic reading doesnt change, or goes up! The needle is a bit mroe reliable although at around the quarter tank mark it goes up and down at random... Quote Link to comment Share on other sites More sharing options...
Husky Posted May 12, 2011 Share Posted May 12, 2011 the distance to empty is a calculation based on how much fuel you have and the MPG you are doing. So, gallons left * mpg = DTE If you hit the ---- you probably still have 50 miles left. The most i ever got out the ---- was 62 miles. I was however then stuck on the side of the A46 waiting for a fuel can. The price for curiosity eh PS: when it runs out of fuel it does just that, run out, completely, with no coughs or splutters Quote Link to comment Share on other sites More sharing options...
Blacky Posted May 12, 2011 Share Posted May 12, 2011 Mines to bloody accurate, all it ever does is goe down Quote Link to comment Share on other sites More sharing options...
coldel Posted May 12, 2011 Share Posted May 12, 2011 I presume it just cuts out at zero as the tank is pressurised? You literally go down to zero and its gone, rather than it sloshing around down there..! Not sure how my physical measurement goes up and down though! Quote Link to comment Share on other sites More sharing options...
Lincolnbaggie Posted May 12, 2011 Share Posted May 12, 2011 Mine's that inaccurate I bought a scangauge to use the trip function. Reads empty and DTE shows --- when I've still got at least a quarter of a tank left. If I only trusted the fuel gauge I'd be filling up after 250 miles, when I can easily get 350-400 out of a tankful. If you boot the car it drops like a stone, and climbs back slowly if you go steady. Quote Link to comment Share on other sites More sharing options...
Wasso Posted May 12, 2011 Share Posted May 12, 2011 Mines to bloody accurate, all it ever does is goe down And to make it go back up is the price of a small mortgage!! I try not to look at the fuel pump when filling up, it's shocking now how fast the £'s go as you're litres are just slowly ticking over! The horrible part of filling up is you put £60 in and it only just goes above half way. I get so angry leave the petrol station and put my foot down in anger, then kick myself because I've just used quarter of a tank!! But the smile whilst hitting that loud pleasure is worth every penny - which is why we all keep filling up! Quote Link to comment Share on other sites More sharing options...
glrnet Posted May 12, 2011 Share Posted May 12, 2011 +1 Mine's that inaccurate I bought a scangauge to use the trip function. Reads empty and DTE shows --- when I've still got at least a quarter of a tank left. If I only trusted the fuel gauge I'd be filling up after 250 miles, when I can easily get 350-400 out of a tankful. If you boot the car it drops like a stone, and climbs back slowly if you go steady. Quote Link to comment Share on other sites More sharing options...
Rob_Quads Posted May 12, 2011 Share Posted May 12, 2011 Mines very inaccurate. Just last week the red light went on...35 miles to go.....3 days later after driving to work...46 miles to go and the guage had been going up and down each day. I really really really hate the fact that the fuel guage is electronic. I really wish that the readout was a how much is left in my tank, not how far can I go. IMO fueld guages should be linear petrol volume gauges and leave the rest to the digital guages Quote Link to comment Share on other sites More sharing options...
chrisgunton Posted May 12, 2011 Share Posted May 12, 2011 Interesting - my OBDII reader (Rev on the iPhone) doesn't report fuel level. How is the ScanGauge picking up on it? Do you have a newer Zed? Mines a 2004. Quote Link to comment Share on other sites More sharing options...
Keyser Posted May 12, 2011 Share Posted May 12, 2011 Mine hangs around full for quite a while then drops like a stone to quater mark hangs there for the next 80 odd miles then plummets the rest of the way down in the space of 5 miles and little flashing lights tell me I need to check the overdraft again. Quote Link to comment Share on other sites More sharing options...
MadMac Posted May 12, 2011 Share Posted May 12, 2011 Fuel Guage = Accurate generally. TripComputer = Not Accurate The computer is just trying to make an educated guess, but it doesn't actually know exactly how much fuel you have in there. My AA man friend is always complaining about rescuing people who watch the trip computer and not the actual fuel gauge. Quote Link to comment Share on other sites More sharing options...
DP7657 Posted May 12, 2011 Author Share Posted May 12, 2011 They're both as bad as each other if you ask me! The petrol station's not all bad with the Zed I suppose, get a lot of looks there these days Quote Link to comment Share on other sites More sharing options...
Rob_Quads Posted May 12, 2011 Share Posted May 12, 2011 Fuel Guage = Accurate generally.TripComputer = Not Accurate The computer is just trying to make an educated guess, but it doesn't actually know exactly how much fuel you have in there. . They both work off the same measurement tho. The Fuel gauge is also trying to guess. How else can you explain the gauge regularly going back up as i drive more economical. Quote Link to comment Share on other sites More sharing options...
bronzee Posted May 13, 2011 Share Posted May 13, 2011 The gauge on mine is accurate. But when I was having major issues with harmonics in the car years back, the vibration damaged the fuel pump and the gauge would jump and down very erratically, even when the tank was completely full or half. Action, new fuel pump, and no more issues. Probably something completely different for you guys though. Quote Link to comment Share on other sites More sharing options...
MadMac Posted May 13, 2011 Share Posted May 13, 2011 Fuel Guage = Accurate generally.TripComputer = Not Accurate The computer is just trying to make an educated guess, but it doesn't actually know exactly how much fuel you have in there. . They both work off the same measurement tho. The Fuel gauge is also trying to guess. How else can you explain the gauge regularly going back up as i drive more economical. Each car is different, and to be honest, I don't know about the Z guages to understand it, but, the major contributing factor it the shape of the tank. Every car fuel tank is irregularly shaped because, let's face it, trying to fit a perfectly simetrical fuel tank in a car is never going to happen. But they are usually bigger at the top than they are at the bottom, so if you put fuel in you will find in most cars, the first half a tank on the gauge goes down slowly, then you get your last half empty much faster. But the gauge isn't usually designed to take that into account. Then you also add in, if your driving like a loony, just like when swirl a drink round a glass, most of the fuel is sloshing around the tank, but the reader can't compensate for that so it thinks you have less. (this was usually pretty obvious in old cars, my old escort, the fuel gauge would drop to empty when I went round a corner quickly!) When you drive normally, the fuel isn't sloshing about so you get a more accurate reading. After all the sensor in the tank is usually just a float on the end of a rod. It's kinda like to sticking your hand in a bucket of water, you know how much water it can hold, an your friend is taking a cup of water out every few seconds, so you know that too, but you have to guess how much is actually in there, it's even harder when it's sloshing about or a funny shaped bucket. I've typed this on my iPhone on a train, please excuse the spelling and grammatical errors. Quote Link to comment Share on other sites More sharing options...
Lincolnbaggie Posted May 13, 2011 Share Posted May 13, 2011 Interesting - my OBDII reader (Rev on the iPhone) doesn't report fuel level. How is the ScanGauge picking up on it? Do you have a newer Zed? Mines a 2004. No, mine's an 04 as well. The scangauge has quite a good trip computer built into it - you set the fuel tank size and then press a couple of buttons every time you fill up and it calculates over a few fill-ups what the inaccuracy of the car's computer is and adjusts automatically. It reckons the car computer is about 30% incorrect. I have the DTE reading on the scangauge as one of the parameters on show and I know how much I have left (either in miles to go, or litres left). Much better than the car display (which I have on mph anyway as I can't read the speedo easily when driving). Only thing that annoys me is the car display still flashes "DTE - 40 miles" when I've got over 200 miles left and you can't turn the thing off permanently. Quote Link to comment Share on other sites More sharing options...
Wez21 Posted May 13, 2011 Share Posted May 13, 2011 Hi, the fuel pointer is moved by a resistance input from the fuel sender, which should not go up and down as much as it does, even with the fuel slopping about. The eeprom data in the combi-meter is written to update the gauge at regular intervals or when the car is started. One theory I have is that the eeprom data is not entirely correct for the fuel circuit, it seems as if it is using part of the calculation from the dte to try and level out the fuel pointer, but with the error it is making it go up slightly!!! In Japan where our cars where made they did not have the stricted of tolerances to this, coupled with the fact our combi-meters use cross coil motors, newer cars now use stepper motors which are easier to control!! 1 good thing though is it appears they have set the flashing dashes warning to com eon when you have 11 litres left in the tank. Nissans made in the UK have the dashes come on at 4.5 litres left!!! I hope this was helpful! Quote Link to comment Share on other sites More sharing options...
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