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Author Topic: How does it work  (Read 659 times)

Rene T

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How does it work
« on: September 09, 2020, 04:15:06 PM »
My car lets me know how many miles I can go before I need to fill up. When I fill up, sometimes it will say I can go 500 miles and other times it might say 450 miles. I always fill it up to the top of the fill pipe. How does the car know how many miles I can go. As far as I know, there arenít and tank sensors. Do you know if the cars computer uses how the fuel was used the previous tankfull then calculates how far it can go using the miles per gallon statistic.  Thanks
Rene, Lucille & co-pilot Buddy
AKA  Pep N Mem
2011 Chevy Duramax 2500 HD 4X4
2011 Montana High Country 343RL
From the Granite State of NH
& Florida Snowbird in Lakeland FL

NY_Dutch

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Re: How does it work
« Reply #1 on: September 09, 2020, 04:26:01 PM »
It uses your average MPG since the last fill up as part of the formula...
Dutch
2001 GBM Landau 34' Class A
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SpencerPJ

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Re: How does it work
« Reply #2 on: September 09, 2020, 06:06:57 PM »
I always fill it up to the top of the fill pipe.

You need to stop that habit,  It will get gas into your charcoal canister that captures fumes and cause your check engine light to come on, and $100 to replace the canister.  Don't ask me how I know  ;)  Stop at the click... no more :)

I will say that my 2005 YukonXL was FAR superior to estimated mileage, DTE, etc than my new Ford F150.  My F150 asks to click if you are towing a trailer, the old GMC simply used the fuel filter / pump / gauge all in one in the gas tank.  Costly bugger when it needs replaced. 

So I feel the GMC did a continual adjustment as fuel was used and tied into the computer, but I think this new F150 does it a whole lot less frequent.  Also, my old GMC was really accurate, my F150 has a 36 gallon tank, and it will say 40 miles, hence roughly 2 gallons, but I can only get 30 gallons into it.
« Last Edit: September 10, 2020, 06:51:21 AM by SpencerPJ »
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camperAL

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Re: How does it work
« Reply #3 on: September 09, 2020, 06:19:56 PM »
Hi Rene and all,

One thing that effects gas mileage is how much alcohol is used at various filling stations. I've varied by about 100 miles because I got more pure gas than some stations that have 10% alcohol in their fuel.
CamperAL (Indiana)
(2006 Coachmen Mirada 290 KS )

Rene T

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Re: How does it work
« Reply #4 on: September 09, 2020, 06:36:45 PM »
You need to stop that habit,  It will get gas into your charcoal canister that captures fumes and cause your check engine light to come on, and $100 to replace the canister.  Don't ask me how I know  ;)  Stop at the click... no more :)

Thanks Paul I never heard that before so I guess Iíll have to change a very bad habit. Thanks.
Rene, Lucille & co-pilot Buddy
AKA  Pep N Mem
2011 Chevy Duramax 2500 HD 4X4
2011 Montana High Country 343RL
From the Granite State of NH
& Florida Snowbird in Lakeland FL

edjunior

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Re: How does it work
« Reply #5 on: September 09, 2020, 09:26:58 PM »
You need to stop that habit,  It will get gas into your charcoal canister that captures fumes and cause your check engine light to come on, and $100 to replace the canister.  Don't ask me how I know  ;)  Stop at the click... no more :)

I can verify this, and add my little bit to it.  I would fill my new Dodge Charger like this and always smelled gas in the car after a fill-up.  I always thought it was just something in the way the Charger was built.  Until I read on one of the Charger forums someone else had that problem.  The answer was like SpencerPJ said, stop filling at the first click.  And I actually tested this on a number of fill-ups.  After the first time I stopped at the first click, no fumes in the car.  The next fill-up, I clicked it until I could click no more.  Fumes in the the car.  I did it a couple of more times until I felt that yep, that was what was causing the fumes in the car.  It did take me a while, but I finally kicked the habit.  I now always stop after the first click.  And have not had fumes in the car since.  So believe it!
Ed.....KF5INW
MSgt, USAF, Retired
2019 F-250 XLT, 6.7L PSD
2010 Forest River Wildcat 28RKBS
"I thought I was wrong once, but I was wrong!"

Ex-Calif

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Re: How does it work
« Reply #6 on: September 10, 2020, 05:12:31 AM »
My car lets me know how many miles I can go before I need to fill up. When I fill up, sometimes it will say I can go 500 miles and other times it might say 450 miles. I always fill it up to the top of the fill pipe. How does the car know how many miles I can go. As far as I know, there arenít and tank sensors. Do you know if the cars computer uses how the fuel was used the previous tankfull then calculates how far it can go using the miles per gallon statistic.  Thanks

They aren't that smart, really.  Modern cars have "more" accurate fuel level sensors and with fuel injection it was easy for them to add a fuel flow meter. I drove my nieces Chevy Cruze from Tennessee to Ohio. It was blown away by the mileage. However the range on surface streets for about 10 miles was like 380 and when I got on the freeway it slowly started going up to like 420. It was weird to be driving and watch the range going up.

Ditto on not overfilling the tank. I generally will do one extra click after the auto shut off.
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John From Detroit

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Re: How does it work
« Reply #7 on: September 10, 2020, 06:21:23 AM »
My car lets me know how many miles I can go before I need to fill up. When I fill up, sometimes it will say I can go 500 miles and other times it might say 450 miles. I always fill it up to the top of the fill pipe. How does the car know how many miles I can go. As far as I know, there arenít and tank sensors. Do you know if the cars computer uses how the fuel was used the previous tankfull then calculates how far it can go using the miles per gallon statistic.  Thanks

First there IS a tank sensor (The fuel gauge, the least accurate of all gauges per some folks)  So it knows the thank is reporting "FULL" or "Half full"

THen there are the fuel metering jets. the computer knows how much fuel you pump per mile often averaged over the last 50 or some other length of miles.

It also knows how much the tank holds

And from there it's a simple division job.  Very easy for a computer.
Nothing adds excitement like something that is none of your business
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Mark_K5LXP

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Re: How does it work
« Reply #8 on: September 10, 2020, 07:42:03 AM »
Since the advent of these things DW is convinced that there's no way they can be right.  Because I consistently average 4MPG more than her, and she's a "waaay better" driver than I am.  I tried to describe how it's probably due to how I use that linear range the gas pedal has between idle and floored but that's just silly talk.  More interesting than how range is calculated is just how close it will get to predicting remaining miles.  I had one car I've run down to single digits but didn't have the guts to see if it would hit zero, or just how far it would go past that before I was walking.  The current car just says "less than 50 miles remaining" so that's quite a bit of error margin.  The remaining oil life is another one.  Some are strictly odometer counters but others actually factor in highway vs city driving.  All of this displayed on a little 2-line dot matrix display next to the speedometer that I have to poke a button to scroll through.  Meanwhile there's a 6x10" full color display in the center console that for the most part controls the radio and not much else.  For radio station presets it uses tiny fonts above the buttons you can't see, a similarly sized time and temperature, and giant color icons in the middle for things that never change.  If the instrument display department could get with the infotainment system department maybe they could come up a vehicle user interface that was actually useful.  Nah...

Mark B.
Albuquerque, NM

jubileee

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Re: How does it work
« Reply #9 on: September 10, 2020, 08:56:38 AM »
  Cars are smart and have been for sometime. Our newest is a 2007 Tahoe flex fuel. 55000 miles.  Bought new. Didnít even notice the flex fuel option. You put more than 3 gallons of gas in it and it recalculates the alcohol content of the whole tank. Shows up on the scanner.

Gary RV_Wizard

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Re: How does it work
« Reply #10 on: September 10, 2020, 09:56:09 AM »
Most of the vehicles I'm familiar with use a "rolling average" mpg, which is continuously recalculated as you drive.  That average is divided into the current tank level reading (the fuel gauge) to estimate the remaining miles of driving. Think of it as   "You can go xxx miles at your current rate of fuel consumption".
My daughter's Kia uses the last 35 miles for the rolling average mpg while my Cadillac uses the last 50 miles.
Gary
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darsben

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Re: How does it work
« Reply #11 on: September 10, 2020, 12:22:41 PM »
Off topic but another good question is; How does a thermos know how to keep hot food hot and cold foods cold? ;) ;D :o
1990 Fleetwood Southwind on P30 chassis located in
Central NY in summer and beautiful Casa Grande AZ in winter

glen54737

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Re: How does it work
« Reply #12 on: September 10, 2020, 01:58:24 PM »
Most of the vehicles I'm familiar with use a "rolling average" mpg, which is continuously recalculated as you drive.  That average is divided into the current tank level reading (the fuel gauge) to estimate the remaining miles of driving. Think of it as   "You can go xxx miles at your current rate of fuel consumption".
My daughter's Kia uses the last 35 miles for the rolling average mpg while my Cadillac uses the last 50 miles.

My Ford per the manual uses the last 500 miles

My wife couldn't understand why when towing it would show 250 when full but when not towing it was 450-500.
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Glen,Nene
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Rene T

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Re: How does it work
« Reply #13 on: September 10, 2020, 02:02:52 PM »
Off topic but another good question is; How does a thermos know how to keep hot food hot and cold foods cold? ;) ;D :o

You can probably get your answer by getting a bucket of steam, pour it into the thermos and see what happens.   :o ::) :-\ :'( ;)
Rene, Lucille & co-pilot Buddy
AKA  Pep N Mem
2011 Chevy Duramax 2500 HD 4X4
2011 Montana High Country 343RL
From the Granite State of NH
& Florida Snowbird in Lakeland FL

Larry N.

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Re: How does it work
« Reply #14 on: September 10, 2020, 02:30:35 PM »
Off topic but another good question is; How does a thermos know how to keep hot food hot and cold foods cold? ;) ;D :o
Actually, it's that new miniaturized smart computer they put in there -- it reads the inside temperature.  ::) :o 8) ??? ;D ;D
Larry and Mary Ann N.
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John From Detroit

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Re: How does it work
« Reply #15 on: September 10, 2020, 05:21:04 PM »
Off topic but another good question is; How does a thermos know how to keep hot food hot and cold foods cold? ;) ;D :o

Magic of course.
Actually I do know the correct answer but Magic is more fun.
Nothing adds excitement like something that is none of your business
My Home is where I park it.

edjunior

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Re: How does it work
« Reply #16 on: September 10, 2020, 08:37:24 PM »
Off topic but another good question is; How does a thermos know how to keep hot food hot and cold foods cold? ;) ;D :o

Everybody knows, it's Juicedratics.
Ed.....KF5INW
MSgt, USAF, Retired
2019 F-250 XLT, 6.7L PSD
2010 Forest River Wildcat 28RKBS
"I thought I was wrong once, but I was wrong!"

NY_Dutch

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Re: How does it work
« Reply #17 on: September 10, 2020, 08:37:35 PM »
Off topic but another good question is; How does a thermos know how to keep hot food hot and cold foods cold? ;) ;D :o

They don't work! I put a popsicle and hot coffee in one and ended up with a luke warm mess... ;)
Dutch
2001 GBM Landau 34' Class A
F53 Chassis, Triton V10, TST TPMS
2011 Toyota RAV4 4WD/Remco pump
ReadyBrute Elite tow bar/Blue Ox base plate

darsben

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Re: How does it work
« Reply #18 on: September 11, 2020, 09:41:25 AM »
They don't work! I put a popsicle and hot coffee in one and ended up with a luke warm mess... ;)
You probably put them in, in the wrong order.
This is not the thermos fault
1990 Fleetwood Southwind on P30 chassis located in
Central NY in summer and beautiful Casa Grande AZ in winter

NY_Dutch

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Re: How does it work
« Reply #19 on: September 11, 2020, 07:12:33 PM »
You probably put them in, in the wrong order.
This is not the thermos fault


 :o ;D ;D ;D
Dutch
2001 GBM Landau 34' Class A
F53 Chassis, Triton V10, TST TPMS
2011 Toyota RAV4 4WD/Remco pump
ReadyBrute Elite tow bar/Blue Ox base plate

Derby6

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Re: How does it work
« Reply #20 on: September 15, 2020, 06:23:25 PM »
You need to stop that habit,  It will get gas into your charcoal canister that captures fumes and cause your check engine light to come on, and $100 to replace the canister.  Don't ask me how I know  ;)  Stop at the click... no more :)

I can verify this, and add my little bit to it.  I would fill my new Dodge Charger like this and always smelled gas in the car after a fill-up.  I always thought it was just something in the way the Charger was built.  Until I read on one of the Charger forums someone else had that problem.  The answer was like SpencerPJ said, stop filling at the first click.  And I actually tested this on a number of fill-ups.  After the first time I stopped at the first click, no fumes in the car.  The next fill-up, I clicked it until I could click no more.  Fumes in the the car.  I did it a couple of more times until I felt that yep, that was what was causing the fumes in the car.  It did take me a while, but I finally kicked the habit.  I now always stop after the first click.  And have not had fumes in the car since.  So believe it!

Interesting as I am a big time topper offer... :)  Doubt I'll change my habits--but I'll keep it in mind. 
Edjunior--your problem is that it was a dodge....LOL
2020 Ford Explorer (Wife's Ride--now my commuter)
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edjunior

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Re: How does it work
« Reply #21 on: September 15, 2020, 08:14:53 PM »
Interesting as I am a big time topper offer... :) 
Edjunior--your problem is that it was a dodge....LOL

Oh, c'mon now.  Be nice.  I have my Ford truck!  The Charger started out being my wife's car, but stuff happens, and I started driving it to work.  76 miles round trip.  5 days a week.  The car has been great.  But it's been sitting in the driveway now since March.  Driven only enough to clean the exhaust now and then.  Stupid Covid crap!
Ed.....KF5INW
MSgt, USAF, Retired
2019 F-250 XLT, 6.7L PSD
2010 Forest River Wildcat 28RKBS
"I thought I was wrong once, but I was wrong!"

Derby6

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Re: How does it work
« Reply #22 on: September 17, 2020, 04:16:02 PM »
LOL--Right on!
My new commuter was hand me down from wife too.
And we are both military retirees...albeit you were AF... :D  Army here.
A lot in common!!!

HiJack complete.
2020 Ford Explorer (Wife's Ride--now my commuter)
2019 Ford F350 4x4 Lariat Crew Cab/Long Bed/SRW
2015 Ford Explorer (Wife's previous Ride--now my commuter)
2007 28' Desert FOX Toy Hauler
1996 Dodge 1500 -- (Plow Truck)             
TOYS:
12 Yamaha Grizzly 450
13 Yamaha Rhino 700 (Wifes Ri

blw2

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Re: How does it work
« Reply #23 on: September 18, 2020, 02:08:44 PM »
You need to stop that habit,  It will get gas into your charcoal canister that captures fumes and cause your check engine light to come on, and $100 to replace the canister.  Don't ask me how I know  ;)  Stop at the click... no more :)

I did the same think in my 2006 Silverado.  I don't remember the cost to repair it... I want to say I bought the part and did it myself, but I'm not even sure about that.  Reagrdless...I'll sometimes pack in a little past the click but no longer stuff the pipe full.

and yeah, I suppose different car models probably use different variables to calculate taht range.  I just bought an electric car and I'm trying to figure out this one....  I'm not sure if it weights the averages of the last drive...the last charge (or tank), the life average, or what....
Brad (DW + 3 kids)
í13 Thor Chateau 31L Class C on Ford E-450
'06 Silverado
'05 Rockwood Freedom 1910 (5-1/2 years)
former tent campers