trouble with reporting full tank

[robinlevin0101]

The only time my car displayed 325 miles till empty was the day i drove off the lot. Since than every fill up only registers about 290-299 miles till empty. I know there is at least another 25 available and i manually have pressed the handle but Ive never seen 300 or 325 come up after a fill. Extremely frustrating as I need to make it to vegas on one tank and that requires at least 310 miles. Anyone else that doesn't see a full tank with the numbers displayed?

 

[Sixonemale]

I'm purely guessing because I'm not sure how the computer works. The day you drove it off the lot there may have been a default MPG inputted when the vehicle was new. I believe the size of gas tank is 18.6 gallons, therefore it could have had a default of 17.5 MPG to calculate 325 miles till empty. Not sure what you average in MPG, but if it is saying 290 to 299 miles till empty, based on a 18.6 gallon tank, that would mean that you are averaging 15.6 to 16.0 MPG, respectively. So, if the MPG that I just mentioned are from city driving and all of the sudden you drive on the highway, you are correct, you will have more miles till empty, IF this is how the computer calculates miles till empty.

 

[peterk9]

The only time my car displayed 325 miles till empty was the day i drove off the lot. Since than every fill up only registers about 290-299 miles till empty. I know there is at least another 25 available and i manually have pressed the handle but Ive never seen 300 or 325 come up after a fill. Extremely frustrating as I need to make it to vegas on one tank and that requires at least 310 miles. Anyone else that doesn't see a full tank with the numbers displayed?

Welcome to the Forum robin.
The Miles to Empty (MTE) figure is based on the average mileage of the last tank. When you drove it off the lot do you know if the Average Miles Per Gallon figure was reset? It is quite possible that that fuel was added to the tank without resetting it. If so, it will result in a false MTE reading. It will be higher than actual. Since there are unknowns before you drove off the lot, I'd tend to go with what you do know since you've driven it and filled it. Also, the Instant MPG reading on the dash is more generous than the actual MPG.

Peter

 

[Sixonemale]

Bottom line is the MPG is based on a rolling average after it's reset. More specifically, I have not reset my MPG in a long time and lets say it reads 18 MPG. No matter where or how far I drive it won't go very far up or down because the calculation is based on rolling average of lots of miles. So, if I filled my tank up tomorrow, the miles to empty should read 18 x 18.6 or about 334 miles to empty, assuming I filled the tank to capacity. If I were to reset my MPG one mile into a long highway trip, which I've done before, I may get an average of 21 MPG at the end of the trip, but if I were to fill up right after that trip I don't think it would calculate 21 x 18.6 or about 391 miles to empty, I think the miles to empty is based on lots of miles traveled or has a maximum MPG that it's calculated from so that it does not deceive owners and leave them stranded.

 

[peterk9]

I believe he is talking about the Miles to Empty figure that shows up after the tank is filled which is based on the previous tank's MPG figure. I believe the DTE is based on the current MPG the vehicle is getting. How does the Distance to Empty calculation work?

Peter

 

[blwnsmoke]

I believe he is talking about the Miles to Empty figure that shows up after the tank is filled which is based on the previous tank's MPG figure. I believe the DTE is based on the current MPG the vehicle is getting. How does the Distance to Empty calculation work?

Peter

He is but it all ties together. The mpg is distance along with fuel used. The DTE is the average mpg along with how much fuel is in the tank based on the fuel level sensor. So if your mpg goes down, so will your DTE on the next tank.

It also doesnt calculate a reserve which us built into the 18.6 gallon.

 

[Sixonemale]

I believe he is talking about the Miles to Empty figure that shows up after the tank is filled which is based on the previous tank's MPG figure. I believe the DTE is based on the current MPG the vehicle is getting. How does the Distance to Empty calculation work?

Peter

I agree he is talking about the miles to empty and not DTE, so I cleaned up my post above to reflect this.

I'm not sure what you mean by based on the previous tank's MPG figure, because some times the tank is filled from the 1/4 mark and some times from the 1/2 mark, etc., all over the place. So maybe what you are saying is that the miles to empty is based on the MPG that were achieved over the last 18.6 or so gallons of gas, or on a rolling average.

I agree that the DTE is related to the MPG that the vehicle is currently getting. If you are driving up a long grade and reach the DTE mark, the reading would be less than if you were traveling at 65 MPH on a flat highway, and I believe will change based on the driving conditions on the way to empty.

 

[peterk9]

I agree he is talking about the miles to empty and not DTE, so I cleaned up my post above to reflect this.

I'm not sure what you mean by based on the previous tank's MPG figure, because some times the tank is filled from the 1/4 mark and some times from the 1/2 mark, etc., all over the place. So maybe what you are saying is that the miles to empty is based on the MPG that were achieved over the last 18.6 or so gallons of gas, or on a rolling average.

Yes, that is right. The reading of the previous tank's MPG average readout, regardless of how much gas was put in. If the driver made several short trips or used WOT during that time, the Miles to Empty are going to be lower after filling up than if there were lots of highway miles and no WOT occasions.

Peter

 

[reserved50]

it learns how you drive, previous person that drove the vehicle got better mileage. It can be reset to show maximum per tank but will automatically adjust after it has learned how you drive to give a better indication to empty. Other than that make sure you know where the emergency fuel funnel is in the vehicle and carry a 2gal backup gas can?

When I upload a performance tune to a vehicle it automatically resets the DTE to factory, since it does a memory wipe.