PaulS_ Posted June 18 Posted June 18 Hi all, I'm getting a refuel light at just under 200km. I'm presuming that this is not normal behaviour...? It's a fairly new import, and wanted to run the fuel down to check the refuelling light point.
Rojie Posted June 18 Posted June 18 37 minutes ago, PaulS_ said: Hi all, I'm getting a refuel light at just under 200km. I'm presuming that this is not normal behaviour...? It's a fairly new import, and wanted to run the fuel down to check the refuelling light point. Grim ! On a full tank ? 65 litres, or so. Have you had a speedo chip fitted to convert to mph from kph ?
BigNev Posted June 18 Posted June 18 Hi everyone! Hope you are all well! Well, lets hope something here is screwy, or you're getting an absolutely dire 9mpg. Was the fuel tank actually full? Is that range remaining? Have you had it sat idling for hours? My calcs - 65 litres divide 4.54 = 14.32 gallons, 196km = 122 miles 122 divide 14.32 equals more than awful, almost unobtainable, 8.52 mpg. Surely it cannot be!!!!
Rojie Posted June 19 Posted June 19 Can you change your location please ? Maybe we can muster some local help.
PaulS_ Posted June 19 Author Posted June 19 (edited) 8 hours ago, Rojie said: Can you change your location please ? Maybe we can muster some local help. Thanks @Rojie. Location updated. I think that I'll get in touch with the seller as clearly something is wrong with the electronics. As per your point @BigNev, that seems to be the most likely outcome. If it empties at 200km and with a full tank it's at around 600km, then thankfully it's averaging at 18mpg (ie 400km / 60L). Edited June 19 by PaulS_
Rojie Posted June 19 Posted June 19 1 hour ago, PaulS_ said: Thanks @Rojie. Location updated. I think that I'll get in touch with the seller as clearly something is wrong with the electronics. As per your point @BigNev, that seems to be the most likely outcome. If it empties at 200km and with a full tank it's at around 600km, then thankfully it's averaging at 18mpg (ie 400km / 60L). If this vehicle is a recent purchase from a business, you certainly should return to the seller for further 'discussions' If bought from a business you will have protection under Consumer Lawand should have a warranty of some sort.
BigNev Posted June 19 Posted June 19 (edited) I'm a bit confused now, well a lot actually. "Empties at 200km" - if you filled up and then after 200km you've run out, as the fuel light comes on, what are 600 and 400 km to do with it? Edit - Just come back to this, and have I got it now - that display of 196km is "range left"? So the 600km is when you've filled it? If so, scrap all these thoughts and start again. Fill it back up, see how many litres it takes, over how many miles or km it's done, then calculate it. Simple facts on what it's done. The computer range is definitely NOT a good way to work it out, it's very much a computer "guesstimate" Edited June 19 by BigNev
Rojie Posted June 20 Posted June 20 Computer guesstimates are based on previous use and driving style. Change either and it will throw the calculation out. To clarify what Neville (I think) means. Fill to brim, Note mileage, Run, the further the better, but you do not need to run the tank way down, Fill to brim, Note mileage. Calculate. Distance driven divided by fuel used (amount that was used to refill). Use your normal driving style and normal routes and normal loading. If you can, reset the fuel history before you start the test. 1
PaulS_ Posted June 20 Author Posted June 20 17 hours ago, BigNev said: I'm a bit confused now, well a lot actually. "Empties at 200km" - if you filled up and then after 200km you've run out, as the fuel light comes on, what are 600 and 400 km to do with it? Edit - Just come back to this, and have I got it now - that display of 196km is "range left"? So the 600km is when you've filled it? If so, scrap all these thoughts and start again. Fill it back up, see how many litres it takes, over how many miles or km it's done, then calculate it. Simple facts on what it's done. The computer range is definitely NOT a good way to work it out, it's very much a computer "guesstimate" Thanks Nev and yes, a classic Internet misunderstanding! Sorry for the confusion. You're right, (a) I was trying to say that the refuel light comes on when the calculated range on the dash is at around 200km, and (b) it's absolutely a computer guesstimate. 1
PaulS_ Posted June 20 Author Posted June 20 (edited) 3 hours ago, Rojie said: Computer guesstimates are based on previous use and driving style. Change either and it will throw the calculation out. To clarify what Neville (I think) means. Fill to brim, Note mileage, Run, the further the better, but you do not need to run the tank way down, Fill to brim, Note mileage. Calculate. Distance driven divided by fuel used (amount that was used to refill). Use your normal driving style and normal routes and normal loading. If you can, reset the fuel history before you start the test. You know, I never knew that. I always assumed that the range calculator in any car was simply related to what's in the tank, rather than anything related to current, historical driving styles etc. So, the refuel light coming on at 200km might be related to the driving style and conditions that the previous owner had (one wonders what that might have even been). Thanks @Rojie Edited June 20 by PaulS_
smurf Posted June 20 Posted June 20 I doubt the ECU learns your driving style, but it will do a forward looking calculation based upon the fuel consumption of the last "X" number of miles and the fuel left in the tank. That is how the range left number can go up as well as down on a journey, especially when the tank is nearer to full or empty as a small change in consumption can calculate out to large change in range at the extremes. 2
Rojie Posted June 20 Posted June 20 2 minutes ago, smurf said: I doubt the ECU learns your driving style, but it will do a forward looking calculation based upon the fuel consumption of the last "X" number of miles and the fuel left in the tank. That is how the range left number can go up as well as down on a journey, especially when the tank is nearer to full or empty as a small change in consumption can calculate out to large change in range at the extremes. I agree, the ECU does not' 'learn' your driving style per se; but it does calculate the average fuel consumption, and that is largely affected by historic driving style (i.e. speed, terrain, distance and load). Accordingly, it is that historic average that is used to calculate an estimate of the remaining distance that could be covered. The ECU cannot possibly 'know' future driving style' and has no other variable to use in the calculation. If those variables above change significantly, so will the accuracy (if one is needed) of the prediction. As the 'history of driving', my term, is the main basis for the prediction; resetting the trip, thereby deleting the history, and starting a new history, will discount previous data and base a new calculation on the new data it will acquire over the next few miles. I have a vehicle with two trips (as many do), and by resetting one periodically, the difference between single journey data and, say monthly or quarterly data can be compared. It is surprising what the difference is. I agree the remaining distance can increase, If resetting the trip it can only increase, initially. I use to get much amusement from increasing the remaining distance on a previous 5.3l V12 machine ! Smiles per mile until I arrived at the petrol station. 1 1
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