Low fuel indicator and accuracy of distance remaining indication
07-26-11, 06:38 PM
#16
Lexus Champion
Good suggestion, but after my experience on the phone with Lexus today, I would take that 22.2-gallon capacity with a grain of salt. Maybe they publish a capacity that is deliberately lower than actual for the "safety and convenience" of the customer. Besides, is that published capacity "up the pipe" to near overflow from the filler tube, or "first shut-off" of the nozzle? (And how deep is the nozzle inserted for that first shut off?) I know that when I fill, after first shut-off of the nozzle, I continue to add a fair bit of fuel, although I haven't kept track of exactly how much that ends up being.
When I'm finished doing my little procedure, I'll know what I want to know about our car with more than adequate precision -- information that even Lexus dealers and "specialists" either don't know or are unwilling to reveal.
When I'm finished doing my little procedure, I'll know what I want to know about our car with more than adequate precision -- information that even Lexus dealers and "specialists" either don't know or are unwilling to reveal.
I certainly wouldn't risk running my tank dry in an effort to find a more definitive answer. You fuel pump is submerged in the bottom of the tank are uses the fuel as a coolant. If you burn your pump up, it will be a very expensive test.
As an engineer, I suggest this answer just isn't worth the effort and possible risk to obtain. There's a better solution in my opinion. Fill up before your tank is "very low". What will you do with the answer after you get it? You still have to factor in the road conditions before you have an "accurate" answer. Just my opinion.
07-27-11, 12:57 AM
#18
I drive mostly HWY miles and run the needle like 1/8 inch below the bottom mark too often. Seems ya can get 50-60 miles equlas like 2 1/2 gallons from the red light or when the distance gauge goes to needs fuel.
07-27-11, 06:04 PM
#20
Light
07-27-11, 06:50 PM
#21
Why bother? The manual states that the warning light will come on when "the fuel level in the tank becomes very low." That is intended as a courtesy just in case you have forgotten to check your gage and didn't realize how low you tank was. Nothing more, nothing less.
I certainly wouldn't risk running my tank dry in an effort to find a more definitive answer. You fuel pump is submerged in the bottom of the tank are uses the fuel as a coolant. If you burn your pump up, it will be a very expensive test.
As an engineer, I suggest this answer just isn't worth the effort and possible risk to obtain. There's a better solution in my opinion. Fill up before your tank is "very low". What will you do with the answer after you get it? You still have to factor in the road conditions before you have an "accurate" answer. Just my opinion.
I certainly wouldn't risk running my tank dry in an effort to find a more definitive answer. You fuel pump is submerged in the bottom of the tank are uses the fuel as a coolant. If you burn your pump up, it will be a very expensive test.
As an engineer, I suggest this answer just isn't worth the effort and possible risk to obtain. There's a better solution in my opinion. Fill up before your tank is "very low". What will you do with the answer after you get it? You still have to factor in the road conditions before you have an "accurate" answer. Just my opinion.
10-02-11, 04:49 PM
#22
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Today, finally, my wife and I determined how much fuel it takes to turn OFF the low-fuel indicator from a bone-dry fuel tank -- 10.95 litres (10 litres + 950 ml), plus or minus 50 ml. This equals 2.89 US gallons (10.95 litres divided by 3.785 per US gallon).
The low-fuel indicator turned on the other day, so today I loaded the fuel can and custom-graduated 2-litre bottle bottle into the trunk and my wife and I went out for a ride into the countryside with the intention of running out of fuel. At the beginning of the trip the approximate distance remaining as calculated by the car was 48 miles. (This was not the distance remaining when the light first came on, which was considerably more, although, unfortunately, I cannot remember exactly what.) I reset the trip meter to zero.
To make a short story even shorter, at some point the "distance remaining" indication changed to "low fuel", so it wasn't possible to see the distrance remaining data any longer.
When the car ran out of gas, we had driven 56 miles. So, as far as our particular car is concerned, the distance remaining data is conservative, at least until the display changed to "low fuel". Too bad it doesn't hang in there until the bitter end, because maybe it gets more accurate the close you get to bone dry.
Someone else reported earlier in this thread that the fuel-gauge needle goes below the E mark well before running out of gas. As you can see on the photo below, this is indeed correct. Note on the photo (taken by my wife as we were moving down the road) that the photo was taken when the trip total at that point was only 21 miles. From this point on, the needle moved down only just a little bit, then stopped moving. Again, the car didn't conk out until the trip meter reached 56 miles, so there was still at least 30 miles travelling distance (on pretty level road) after the needle was both buried and became motionless.
I know much more about the fuel situation in our 2005 LS430 than I used to. I hope this information may be of some use for other owners.
(As you can also see, our car is going to have 20,000 miles on it pretty soon. High mileage, eh?)
The low-fuel indicator turned on the other day, so today I loaded the fuel can and custom-graduated 2-litre bottle bottle into the trunk and my wife and I went out for a ride into the countryside with the intention of running out of fuel. At the beginning of the trip the approximate distance remaining as calculated by the car was 48 miles. (This was not the distance remaining when the light first came on, which was considerably more, although, unfortunately, I cannot remember exactly what.) I reset the trip meter to zero.
To make a short story even shorter, at some point the "distance remaining" indication changed to "low fuel", so it wasn't possible to see the distrance remaining data any longer.
When the car ran out of gas, we had driven 56 miles. So, as far as our particular car is concerned, the distance remaining data is conservative, at least until the display changed to "low fuel". Too bad it doesn't hang in there until the bitter end, because maybe it gets more accurate the close you get to bone dry.
Someone else reported earlier in this thread that the fuel-gauge needle goes below the E mark well before running out of gas. As you can see on the photo below, this is indeed correct. Note on the photo (taken by my wife as we were moving down the road) that the photo was taken when the trip total at that point was only 21 miles. From this point on, the needle moved down only just a little bit, then stopped moving. Again, the car didn't conk out until the trip meter reached 56 miles, so there was still at least 30 miles travelling distance (on pretty level road) after the needle was both buried and became motionless.
I know much more about the fuel situation in our 2005 LS430 than I used to. I hope this information may be of some use for other owners.
(As you can also see, our car is going to have 20,000 miles on it pretty soon. High mileage, eh?)
11-08-11, 12:37 PM
#24
Very Low Fuel
My low fuel indicator came on and then my distance to empty stated I had around 40 miles to go. After about 10 more miles of driving, the distance to empty disappeared and it stated Low Fuel (like the post above). I drove another 10miles before filling up. It took just over 21 gallons of fuel before the fuel nossel shut off. I pushed this full up longer than I should've.
11-21-11, 03:19 PM
#25
I have well over 50 miles left when the light comes on
It is 24 miles each way from my work. I know that if the light comes on I can make 1 more round trip.
Today the light came about 3 miles after I left my home. The readout was saying 56 miles left at that time. With the readout at about 40-43 miles left it switched to read low fuel. When i got back to the station near my home I refilled and it took 21.4 gallons so .8 gallons was left.
I put 547 miles on that tank at an average of 25.6 mpg on the readout for that tank and that also calculates to 25.6 mpg. 360 miles of that tank was interstate usually at about 80 mph.
i'm surprised that the tank mpg readout is that accurrate. The miles left readout is slightly conservative, at least on my car.
I also know that I can drive that 48 mile roundtrip in my LS400 with the light on. i've done it many times.
I haven't run out of gas yet and don't push it in any car that I am not very familiar with.
Today the light came about 3 miles after I left my home. The readout was saying 56 miles left at that time. With the readout at about 40-43 miles left it switched to read low fuel. When i got back to the station near my home I refilled and it took 21.4 gallons so .8 gallons was left.
I put 547 miles on that tank at an average of 25.6 mpg on the readout for that tank and that also calculates to 25.6 mpg. 360 miles of that tank was interstate usually at about 80 mph.
i'm surprised that the tank mpg readout is that accurrate. The miles left readout is slightly conservative, at least on my car.
I also know that I can drive that 48 mile roundtrip in my LS400 with the light on. i've done it many times.
I haven't run out of gas yet and don't push it in any car that I am not very familiar with.
11-21-11, 09:45 PM
#26
Jac, That is the bottom line to this crazy thread. Yet there are those out there who insist they know more than Lexus and run their tanks low sucking up all the stuff into their car's fuel system that I would never want to.
Last edited by DNC; 11-21-11 at 10:34 PM.
11-22-11, 05:14 AM
#27
I wasn't recommending that others do this. I was just saying that the readouts are accurate and you don't have to freak out when the low fuel light comes on. In my particular case there are only 2 gas stations along my trip and I would not want to get gas from either one of them.
I usually get gas within 5-10 miles of when the light comes on. If I have a quarter of a tank of junk floating around then I'll be looking for another gas station. I am an engineer and know better than to suck it dry.
I usually get gas within 5-10 miles of when the light comes on. If I have a quarter of a tank of junk floating around then I'll be looking for another gas station. I am an engineer and know better than to suck it dry.
11-22-11, 12:04 PM
#28
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From my personal experience with Lexus in this matter, I am absolutely certain that I know more about how much fuel is left in our unit's tank when that low-fuel light comes on than Lexus does (or, if it does, it is information that Lexus does not allow its representatives to release to its customers).
Therefore, those owners who want information about this issue should read my last post above, and those who think that knowledge is a dangerous thing should just follow the advice of an automobile manufacturer.
11-22-11, 03:02 PM
#29
Tony, let me get this straight, you think this light is going to tell you exactly how much fuel your car has left and give you that information consistently? And you are going to get the same mileage out of that remaining fuel each time? You are putting too much confidence in that little warning light and your one test. It's just that, a light, not a gauge.
Again, I would not run my car that low on fuel nor would I put that kind of trust in the little light. If the fuel light is on it's past time to fill up,,,just my opinion and you have a right to your opinion.
Again, I would not run my car that low on fuel nor would I put that kind of trust in the little light. If the fuel light is on it's past time to fill up,,,just my opinion and you have a right to your opinion.
11-22-11, 03:49 PM
#30
Driver School Candidate
Anyone that runs out of gas on a 22 gallon tank deserves to push their car.
Just kidding, but I do agree that this experiment isn't worth it and results may vary. The trip meter is fairly inaccurate - after fills I have had it range from 297 remaining miles and as high as 414 remaining miles. I've also had the gas light on, parked the car, got back in, and the light wasn't on anymore. I don't even know if filling up the car is an accurate way to measure things as I've filled up 22 gallons at a gas station before, which means I ran it empty (shady gas station pump?). I would just say you have 2-3 gallons left by the time the light comes on. I get really worried when remaining miles is no longer numerical.
And running out of gas is no joke. I've run out of gas in my convertible M3 during a date once. Very embarrassing.
Just kidding, but I do agree that this experiment isn't worth it and results may vary. The trip meter is fairly inaccurate - after fills I have had it range from 297 remaining miles and as high as 414 remaining miles. I've also had the gas light on, parked the car, got back in, and the light wasn't on anymore. I don't even know if filling up the car is an accurate way to measure things as I've filled up 22 gallons at a gas station before, which means I ran it empty (shady gas station pump?). I would just say you have 2-3 gallons left by the time the light comes on. I get really worried when remaining miles is no longer numerical.
And running out of gas is no joke. I've run out of gas in my convertible M3 during a date once. Very embarrassing.