distance / miles to get fuel problem with gauge?
- Thread starter killaj131
- Start date
I just got the oil changed in October, and I use the car starter right now cause of winter but I dont think that should affect the mile odometer when I fill it up, and I usually full it up when it gets to about 60 mile and when I get done filling it up it says I put 9 gallons in.
This. If you sit in your car with the car running and watch the MPG indicator, you will see it go down as you burn fuel and get 0 MPG. And the winter gas blend sold this time of year means even less MPG. What you are seeing is normal.
Swordsmith
242hp/252 ft-lbs BNR EFI
The "miles to empty" calculation is done by looking at your overall mpg, and how full the car thinks its tank is. If you get 40 mpg and have 10 gallons left, then 400 miles to empty. But if you get 22 mpg ordinarily, then that same 10 gallon tank will read 220 miles to empty.
I say "the car thinks" because it's become increasingly clear to me that the computer doesn't have a sensor that tells it how much liquid is actually in the tank, nor does it seem to have one that monitors the flow through the pump. It's using some other information to make its guesses, which means that running significant amounts of ethanol really screws up its estimates, since the energy density is wildly different from what it expects.
If you're using Ultragauge there are ways to program those parameters, so you can get more accurate numbers... but it doesn't use those sensors either (probably because as far as I can tell, they just don't exist). Torque, you could probably install sensors and program it to read those PIDs and do the actual math.
It will never be more than an estimate though, because you might end up driving up a mountain in a headwind at 85, cutting your mpg to a fraction of what it normally is... and not get anywhere close to your DTE.
I say "the car thinks" because it's become increasingly clear to me that the computer doesn't have a sensor that tells it how much liquid is actually in the tank, nor does it seem to have one that monitors the flow through the pump. It's using some other information to make its guesses, which means that running significant amounts of ethanol really screws up its estimates, since the energy density is wildly different from what it expects.
If you're using Ultragauge there are ways to program those parameters, so you can get more accurate numbers... but it doesn't use those sensors either (probably because as far as I can tell, they just don't exist). Torque, you could probably install sensors and program it to read those PIDs and do the actual math.
It will never be more than an estimate though, because you might end up driving up a mountain in a headwind at 85, cutting your mpg to a fraction of what it normally is... and not get anywhere close to your DTE.
There's a gnome named MPGnome that lives in your tank and reports how much is left to the ecu!
rdss
Junior Member
If it didn't know how much fluid was in the tank the fuel gauge in your dash wouldn't work and if it didn't know how much fuel it was adding for combustion your car wouldn't run. The only thing I agree with is the Ethanol content, without the sensor a standard sonic assumes the gas is pretty much the same all the time with little fuel type "learning".
mitdr774
also a dinner prick
GM is not known for very accurate fuel level gauges. Really when you think about it a float attached to a variable resistor in a somewhat wide and short tank of liquid probably will not be all that accurate.
My miles to empty will vary with driving conditions. If I sit and idle it will go up for a short time, but as soon as I start driving again it will drop a decent amount. Drive in the city for and it will be low, hit the highway and the number will go up. It all depends on how you are driving and if you let the car idle/warm up.
My miles to empty will vary with driving conditions. If I sit and idle it will go up for a short time, but as soon as I start driving again it will drop a decent amount. Drive in the city for and it will be low, hit the highway and the number will go up. It all depends on how you are driving and if you let the car idle/warm up.
Swordsmith
242hp/252 ft-lbs BNR EFI
It sorta kinda knows how much fuel is left. I've seen the fuel gauge go UP instead of down, and I don't mean just flashing up for a couple seconds, I mean it was at one bar, then ten minutes later it was at 2 bars and stayed that way for 10 minutes or more before dropping back to 1 bar.
I have an alcohol sensor installed, it doesn't help the DTE figure anything out, I can assure you.
joe truck driver
New member
2 cents
try this if you like. find someplace you can go around a curve or just turn enough to cause considerable body roll in the car( this would mean a safe place) and watch your fuel gauge. when turning left it goes down and when turning right it goes up. maybe your sensor needs adjustment??
try this if you like. find someplace you can go around a curve or just turn enough to cause considerable body roll in the car( this would mean a safe place) and watch your fuel gauge. when turning left it goes down and when turning right it goes up. maybe your sensor needs adjustment??
SonicBoy24
New member
try this if you like. find someplace you can go around a curve or just turn enough to cause considerable body roll in the car( this would mean a safe place) and watch your fuel gauge. when turning left it goes down and when turning right it goes up. maybe your sensor needs adjustment??
that would have to be a long curve for that to happen in these modern cars. Its not like its a float attached to a mechanical gauge like on a old snowmobile or old motorcycle where the float is directly attached to the gauge and and bump will effect the gauge.
Modern cars are programmed to not send every reading of every second to the gauge, if that were so, then yes, every time you took a hard turn or stopped/accelerated hard then your fuel gauge would jump in one direction or the other.
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mitdr774
also a dinner prick
A long entrance/exit ramp with a decent curve to it will cause the miles to empty to change. There are a few around me that will cause up to a 10 mile drop/gain in the estimate. Left hand causes drop and right hand causes a gain.
Cars have a float attached to a variable resistor in the tank. The computer just averages it out over a given time to estimate how much fuel should be in the tank. Some vehicles are sensitive enough that shaking the car will cause the gauge to move though.
Cars have a float attached to a variable resistor in the tank. The computer just averages it out over a given time to estimate how much fuel should be in the tank. Some vehicles are sensitive enough that shaking the car will cause the gauge to move though.
ahtoxa
New member
When you get the tank full, it does look at your recent MPG and estimates from there. If you were using remote starter, idling a lot and driving short distances in cold weather, your MPG could well be in the low 20's. In that case, a full tank could read 260 to empty when you fill up.
If you go and take a long road trip on the highway, turn off and fill up, you'll see that you'll get 400+ until empty.
This number is never constant - how can be? Afterall, you cannot expect to go the same distance on each tank.
If you go and take a long road trip on the highway, turn off and fill up, you'll see that you'll get 400+ until empty.
This number is never constant - how can be? Afterall, you cannot expect to go the same distance on each tank.
SonicBoy24
New member
I have never expereienced this, and I like to take on/off ramps quite, spiritedly.
Trust me, I know how the floats work, I just put in a new in-tank pump and cleaned the resistor on my 86 Fiero.
Quite the project and lots of varnish on the electrical components
2013 Blue Topaz LT
New member
I reset my mpg at every fill-up, that way the average is based per tank.
I also use an old motorcycle habit of resetting the trip meter as well, I know that reaching certain miles will trigger the fuel light, and so far it's been spot on.
I also use an old motorcycle habit of resetting the trip meter as well, I know that reaching certain miles will trigger the fuel light, and so far it's been spot on.
joe truck driver
New member
don't know why the gauge changes on a longer curve but it does.opcorn:
opcorn:
mitdr774
also a dinner prick
don't know why the gauge changes on a longer curve but it does.
The popcorn suggests you are not being serious, but......
As the fuel sloshes to one side of the tank or the other, the fuel level float will go up or down. This will change the fuel level reading and thus the miles to empty guestimate.
joe truck driver
New member
not right place maybe... am trying for 700 plus miles on a tank. been told there is a risk of damage by using the filler tube for the extra fuel. have been able to push an extra 1.35 gallons so far. at 56 mpg.... I could do 720 maybe with 1/2 gallon left in the tank.
