Author Topic: Fuel Gauge  (Read 3963 times)

Lord Voltermore

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Re: Fuel Gauge
« Reply #15 on: April 27, 2022, 05:51:52 PM »


That is true but it doesn't explain why it is a fixed figure immediately after filling up.  I don't suppose it really matters a hoot, it's just that I have now got interested.

Why not?   Once the system knows you now have say 40 litres in the tank  the mk 4  computer is programmed to instantly work out that if your previous  trip was 50 mpg the range  will be  about  439 miles,(assuming you continue to drive in a similar way )or if it  were 75 mpg it would be   659 miles.    The Mk3 may be programmed to initially  always  show 426 miles   ,probably a typical average for the car.    But  either  method will be inaccurate because future mpg is not yet known.   You are unlikely continue driving at  exactly 50 mpg, 75 mpg or the 48 mpg needed for 426 mile range.   
  Trust a dog to guard your house  , but not your sandwich

ColinS

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Re: Fuel Gauge
« Reply #16 on: April 27, 2022, 07:04:05 PM »
The Mk3 may be programmed to initially  always  show 426 miles, probably a typical average for the car.

That was my guess.  You clearly don't know either.  The MK3 obviously operates differently than the MK4.  Anyway it is irrelevant.
« Last Edit: April 28, 2022, 06:52:55 AM by ColinS »

Kremmen

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Re: Fuel Gauge
« Reply #17 on: April 28, 2022, 06:07:08 AM »
The fuel range display using previous saved average mpg makes sense to me. Makes the figure more realistic.

The maths:

Our 40 litre tank is about 8.8 gallons.

600 mile range on 8.8 gallons is about 68mpg

My initial few tank range displays were over 600 miles so I suspect it was based on 70mpg until it got data.

Let's be careful out there !

Lord Voltermore

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Re: Fuel Gauge
« Reply #18 on: April 28, 2022, 09:41:45 AM »
The Mk3 may be programmed to initially  always  show 426 miles, probably a typical average for the car.

That was my guess.  You clearly don't know either.  The MK3 obviously operates differently than the MK4.  Anyway it is irrelevant.
No I dont know  for sure, and I may be wrong.  But on this issue its a logical enough explanation  for me.  Sometimes  ignorance is bliss   :-* 

 There  again Mr Spock was only the first officer.  Captain Kirk was a human.  ;D . I suppose if every one  though  like me we would still be hunter gatherers , but I like to think I am ingenious enough  we would have fast loading multi shot  crossbows capable of taking down a mammoth and live in  comfortable caves.    8)

  Trust a dog to guard your house  , but not your sandwich

nowster

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Re: Fuel Gauge
« Reply #19 on: April 30, 2022, 07:17:07 PM »
On the Mk4 if you top up when the fuel gauge on the right is showing full or just one bar off full, the range estimation doesn't usually update from what it was before you filled up.

JJazz

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Re: Fuel Gauge
« Reply #20 on: April 30, 2022, 07:51:30 PM »
When I picked up my car in September it had 625 on dash. I remember as I asked about it and salesman said number of miles for full tank. I said that’s about 70 mpg. Obviously Honda set it up like that. I will never see that again doing short journeys.
Did calculation - see photo

Kremmen

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Re: Fuel Gauge
« Reply #21 on: May 01, 2022, 04:22:31 AM »
I wonder if the tank range uses just the last MPG or all 3 in the trip computer.
Let's be careful out there !

sportse

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Re: Fuel Gauge
« Reply #22 on: May 01, 2022, 07:46:15 AM »
When I picked up my car with 8 miles on it, the range was 650 miles.

Never repeated, until the car had its battery disconnected for an hour, when it went back to 600+ again.

Over winter I had a range right around 400 miles for months, but with the warmer weather its been showing 480 over the last few fill ups.

Bristol_Crosstar

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Re: Fuel Gauge
« Reply #23 on: May 01, 2022, 08:54:22 AM »
My Crosstar always shows above 500 after filling up, usually 520-540. In practice I've never done more than 450 miles before re-filling (I think there was one block left at that point) so have never put it to the test.

John Ratsey

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Re: Fuel Gauge
« Reply #24 on: May 02, 2022, 09:40:02 PM »
The miles remaining clearly uses recent (I'm not sure how recent - 10 miles??) mpg as that is what is assumed will apply in the future. If you travel down the motorway at 75 mph (ie no better than 50mpg) and stop to refuel then the forecast range on the refill will be nearer 400 miles (40 litres = 8.8 gallons at 50mpg = 440 miles). If you've recently been travelling more slowly and getting 70mpg then the forecast range on refill is over 600 miles (8.8 x 70 = 616 miles). During a journey with different driving conditions you can watch this calculation process. Do some slower driving and the range looks good, then hit the motorway and the miles remaining will go down faster than the miles travelling. Then get back to slower roads and the forecast miles remaining might actually increase although you are using up the miles.
2022 HR-V Elegance, previously 2020 Jazz Crosstar

Kremmen

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Re: Fuel Gauge
« Reply #25 on: May 03, 2022, 05:28:49 AM »
On a similar note, last year I hired a Transit. They noted that the tank range was about 400 miles, I forget the exact figure.

They said that I need to make sure the tank range was no lower when I dropped it off. I only did a 60 mile return journey but the tank range was about 450, and the fuel gauge was still hovering around 3/4 so I didn't put any diesel in  :)
Let's be careful out there !

guest9814

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Re: Fuel Gauge
« Reply #26 on: May 06, 2022, 02:59:11 PM »
On the Mk4 if you top up when the fuel gauge on the right is showing full or just one bar off full, the range estimation doesn't usually update from what it was before you filled up.
MK4 computer recalculate distance to empty always after fuel pass 92% of fuel tank capacity, when you topping up tank to full from empty computer shows what you can get from full tank by judging your previous tank mpg, but why it’s recalculate after passing 92% ?
That because fuel capacity of tank that bigger then 92% not measured in MK4. If tank filled 93-110% it’s full for fuel gauge.
Last fill up I seen 1070km remaining , but when I burned 10% of “full“ fuel tank and drive 144km computer recalculate remaining km from 860 to 970km.

Wonder

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Re: Fuel Gauge
« Reply #27 on: May 06, 2022, 03:16:48 PM »
Hello,
in Italy the car has a 40 liter tank,
and I noticed that the LEDs that indicate the fuel level are 10,
I would think that each LED corresponds to 4 liters (40 liters / 10 LEDs) is an approximation of this type possible or is it too wrong?

JJazz

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Re: Fuel Gauge
« Reply #28 on: May 06, 2022, 09:27:08 PM »
An update on my 467 range after resetting trip when I topped up tank.

Looking at my range it’s now 501 plus I have completed 91.3 miles so looking like 592.3 for my tank of petrol. I still got 10 bars on right. Probably be much changed in a day or two.
« Last Edit: May 07, 2022, 09:53:19 AM by JJazz »

Marmoset

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Re: Fuel Gauge
« Reply #29 on: May 07, 2022, 11:39:05 AM »
An update on my 467 range after resetting trip when I topped up tank.

Looking at my range it’s now 501 plus I have completed 91.3 miles so looking like 592.3 for my tank of petrol. I still got 10 bars on right. Probably be much changed in a day or two.
And looking at things the other way round, with the metre set to return to zero after a fuel refill, I had 357.7 miles done and 264 as range (so 621.7 miles on that rather economical tank) on the way to the petrol station but 580 miles after filling up. So, clearly, the range estimate is not based purely on recent driving. I'm now wondering whether it's taking the life history of the car's consumption figures. 

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