D4 Long Range tanks and fuel usage?

[rapserv]

Just wanting to hear from others who have fitted a LR tank in their D4 .. how their fuel quantities add up.
I have a 170L tank that i have filled choc-a-bloc full .. reset the trip computer .. and then done some extensive driving only to find that the figures don't add up very well.
For example ... filled up in Perth and drove to Kalgoorlie, some 600km and trip computer indicated average fuel consumption of 8.1L/100km. Great!!
Drove around Kalgoorlie for another 300km odd and trip computer advised now 10L/100km.
At around 850km .. the fuel gauge started to indicate a decline and the fuel to empty was around 550km.
Now I'm no math genius .. but but 850 + 550 = 1400km.
Even assuming the average consumption rate was 10L/100km and I have a 170L tank .. then I should get around 1700km per tank of fuel ... if I continue to average 10L/100km .....right?
Surely I can't still have 30+L of fuel remaining in the tank when it's showing empty?

Does anyone know if the fuel monitoring side of things can be reprogrammed with the IID Tool to take account of the new fuel capacity?
I know that the trip computer is not that accurate .. but a 300km per tank discrepency seems to me to be a bit 'excessive'.

[Tombie]

Nope!

You have the gravity fed tank I take it?

The computer can’t work it out.

[gavinwibrow]

Just wanting to hear from others who have fitted a LR tank in their D4 .. how their fuel quantities add up.
I have a 170L tank that i have filled choc-a-bloc full .. reset the trip computer .. and then done some extensive driving only to find that the figures don't add up very well.
For example ... filled up in Perth and drove to Kalgoorlie, some 600km and trip computer indicated average fuel consumption of 8.1L/100km. Great!!
Drove around Kalgoorlie for another 300km odd and trip computer advised now 10L/100km.
At around 850km .. the fuel gauge started to indicate a decline and the fuel to empty was around 550km.
Now I'm no math genius .. but but 850 + 550 = 1400km.
Even assuming the average consumption rate was 10L/100km and I have a 170L tank .. then I should get around 1700km per tank of fuel ... if I continue to average 10L/100km .....right?
Surely I can't still have 30+L of fuel remaining in the tank when it's showing empty?

Does anyone know if the fuel monitoring side of things can be reprogrammed with the IID Tool to take account of the new fuel capacity?
I know that the trip computer is not that accurate .. but a 300km per tank discrepency seems to me to be a bit 'excessive'.


That's about what happened with my 2.7 with the same capacity.

[John_D4]

The trip computer on my D4 is out by a bit. If it claimed 10L/100k then the actual figure is more like 11 or 11.5L. I keep an excel spread sheet record of my fuel usage and calculate my own L/100km and it’s never ever been right.

[John_D4]

Plus I think that 170lt at 11.5lt/100km equals about 1400km. Feel free to correct me if I’m wrong.

How much fuel did you put in to fill it fully after this trip?

[scarry]

The fuel usage dash read out in mine with the standard tank was up to 30% out at times,always optimistic.

LR said they couldn’t sort it and never did.[bigsad]

[rocket rod]

I have the same size tank as you and a spreadsheet of all my fuel use over the life of my D4. The average on the trip computer is usually 9-10l/100, my spreadsheet says 11.3. I've never been able to work out how the computer calculates distance to empty as it doesn't know the tank size and as far as I can ascertain there is no way to change it using GAP tool. In another post I mentioned that, towing a camper trailer, I ran out within 60km from when the light went on. My average fuel use with trailer is 14.3 and without is 11.3. I'm usually off road on gravel or sand with the trailer in tow so it gets a workout.

[BradC]

I've never been able to work out how the computer calculates distance to empty as it doesn't know the tank size and as far as I can ascertain there is no way to change it using GAP tool.

Therein lies the problem. The computer only knows what it was born with and will be merrily assuming it has ~84 usable litres to play with. The fuel gauge does factor into the trip computer also, so it'll get bloody confused when it's done > 500km and the gauge still says the tank is full.

The old 7 series Volvos came with an optional extra tank and there was a link on the back of the gauge you had to cut when that was installed so it knew what it was dealing with.

With so many variations of tank available for the LR and pretty much none of them giving an accurate Full to Empty linear gauge indication it's always going to be fighting an uphill battle. Couple that with a notoriously optimistic assessment of how much fuel it is actually using and it's pretty much never going to get it right.

[Tombie]

Spot on Brad

Litres per 100 consumed is a moving average anyway. Not a since last fill calculation.

[ramblingboy42]

I'm really surprised the manufacturer of the long range tank couldn't at least have designed it to give you a reasonably accurate fuel level on your gauge

[Homestar]

I'm really surprised the manufacturer of the long range tank couldn't at least have designed it to give you a reasonably accurate fuel level on your gauge

The problem is that there isn't a gauge in the long range tank - only the factory gauge and factory tank - the long range tank keeps the factory tank full until it's empty the you have the remaining full factory tank to go - the computer can't make the calculation as it has no idea there's fuel flowing into it keeping it full.

That's my understanding of the system in these and how it was describer to me - was on a road trip in a friends and the gauge didn't move off full until we were half way through NSW (Starting in Melbourne).

[ramblingboy42]

ahhhh , I see, its not a replacement tank but an extra one......

[Bulletman]

My long range tank is seperate and you have to pump from it into the main tank, so i have fount in this situation its very handy as you know when the long range tank is empty and exactly what you have in the main tank.

As for the computer , well its usually close as it still reads from the standard tank ,the distance to empty is a totally different thing as it gets very confused when you keep driving and the tank becomes full again after pumping it from the L/R tank .

Bulletman

[rapserv]

Nope!

You have the gravity fed tank I take it?

The computer can’t work it out.

I suppose the only way to find out just how far a tank will get me is to ...
1. Fill the tank completely
2. Reset the trip meter/ fuel usage
3. Drive until I get a 'low fuel' warning
4. Stop ... and drain the remaining fuel from the tank to see just how much is remaining

If I ensure that there is some fuel in reserve, say 6L out of the remaining fuel, then hopefully I can get an idea of what range I should be able to get out of the remaining fuel.
If I add the indicated mileage/fuel usage to the remaining mileage/fuel usage (less the safety reserve) I should be able to get at least some sort of indication as to what distance I should be able to get from a full tank .. as long as driving conditions don't vary too greatly.

[rapserv]

The problem is that there isn't a gauge in the long range tank - only the factory gauge and factory tank - the long range tank keeps the factory tank full until it's empty the you have the remaining full factory tank to go - the computer can't make the calculation as it has no idea there's fuel flowing into it keeping it full.

That's my understanding of the system in these and how it was describer to me - was on a road trip in a friends and the gauge didn't move off full until we were half way through NSW (Starting in Melbourne).

Yeah ... that's what I expected to happen ... and it did.
The gauge sat there showing full but eventually started decreasing.
It started decreasing earlier than I expected though. I thought I would get to around 1200km before it started to reduce .. but it started at around 850-900km
Regardless of what is being indicated, it seems like the fuel usage figures are greatly inflated .. probably for marketing reasons ... which seems to smack of the old Volkswagon exhaust tampering issue.
I would have thought that there would be an in-line type of 'flow metering' that the vehicle 'smarts' used to determine 'actual' fuel usage which SHOULD give the driver a pretty reliable idea of what the actual range is likely to be .. regardless of the size of tank or feed mechanism.

[Tombie]

As I keep explaining -

(1) The fuel economy is based on lab cycle testing and only for comparison purposes. No VW Style conspiracy involved.

(2) The consumption figure is a moving average - not an average of the tank since last fill.

(3) You can improve its forecast using IID

(4) inline flow meters aren’t used… injector volume x duration is calculated

(5) range calculation is again a moving average - think about it - a flow meter doesn’t know how much it’s going to flow - so how could it calculate range based on that equation. It can only assume based on a known volume and extrapolate from there.


As for your predicament, even though the filler was “full” how much did you manage to put in?
Not unheard of to have a big airlock in the auxiliary.

[rocket rod]

I suppose the only way to find out just how far a tank will get me is to ...
1. Fill the tank completely
2. Reset the trip meter/ fuel usage
3. Drive until I get a 'low fuel' warning
4. Stop ... and drain the remaining fuel from the tank to see just how much is remaining

If I ensure that there is some fuel in reserve, say 6L out of the remaining fuel, then hopefully I can get an idea of what range I should be able to get out of the remaining fuel.
If I add the indicated mileage/fuel usage to the remaining mileage/fuel usage (less the safety reserve) I should be able to get at least some sort of indication as to what distance I should be able to get from a full tank .. as long as driving conditions don't vary too greatly.

Suggest you keep a spreadsheet of usage. I base my usage on the surface that I've mainly travelled on per tank full so I know what I can expect out of a tank for that surface.170289170290

[BradC]

I would have thought that there would be an in-line type of 'flow metering' that the vehicle 'smarts' used to determine 'actual' fuel usage which SHOULD give the driver a pretty reliable idea of what the actual range is likely to be .. regardless of the size of tank or feed mechanism.

Having built one of these for marine diesels you have two sources of error. One is the error on the flow-meter from the tank to the pump, the second is on the flow meter from the return to the tank and that needs accurate temperature compensation also. Frankly unless you pay a *lot* for, and accurately calibrate your flow meters the current method of estimating the injected quantity is far more accurate. The issue with the current method of estimating the injected quantity is Land Rover are really **** at it. The ECU knows pretty much *exactly* how much fuel it's injecting. The trip computer doesn't seem to have access to, or use that information.

[rapserv]

Suggest you keep a spreadsheet of usage. I base my usage on the surface that I've mainly travelled on per tank full so I know what I can expect out of a tank for that surface.170289170290

.. sounds like a good idea to me!

[rapserv]

Having built one of these for marine diesels you have two sources of error. One is the error on the flow-meter from the tank to the pump, the second is on the flow meter from the return to the tank and that needs accurate temperature compensation also. Frankly unless you pay a *lot* for, and accurately calibrate your flow meters the current method of estimating the injected quantity is far more accurate. The issue with the current method of estimating the injected quantity is Land Rover are really **** at it. The ECU knows pretty much *exactly* how much fuel it's injecting. The trip computer doesn't seem to have access to, or use that information.

.. that's what seems to be the issue to me as well.
LR are not adequately using the available real time data .

[Tombie]

They’re able to be recalibrated using IID tools.

Give it a go.

[rocket rod]

.. sounds like a good idea to me!

He's the spreadsheet I use if you like.
170294

[Birdboy]

Not really answering the initial question but in terms of calculating fuel consumption I use a "Car Logbook" App on my phone. Not just for recording work journeys etc, I mainly use it for logging fuel fills and therefore fuel actual fuel consumption. Super easy and it will also give a graph over time of fuel consumption and average. Its super quick and easy to use when you fill up rather than having to put things on a spreadsheet later.

and Yes I can't believe how inaccurate the LR average consumption reading is. Never had a car this bad. over 20% out on mine

[Birdboy]

They’re able to be recalibrated using IID tools.

Give it a go.

thats great to know! I really need to get one I think!

[John_D4]

thats great to know! I really need to get one I think!

Ditto. I wonder if iiD would do a group buy?

[ADMIRAL]

My LoneRanger tank has a separate pump to fill from it to the std main tank, and a bar gauge for fuel level in the extra tank. Works fine as an indicator, and once the fuel is pumped over, the LR gauge works as normal. I use fill to fill for any calculations.

As an aside, have you weighed the D4 with a full tank now you have the reserve tank fitted. I assume you have fitted an external wheel carrier to enable the extra tank to go in. Add a bullbar, and your vehicle weight is getting right up there. I removed a full drawer system and a roof rack once I started towing the van. With around 270 kilos of ball weight, and all the mentioned gear I was in trouble with my GVM. Pays to check.

[StewG]

[With around 270 kilos of ball weight, and all the mentioned gear I was in trouble with my GVM. Pays to check.]

It is not just the GVM but the rear axle max loading that should be checked. At 1855 kg max you could come close or exceed that with minimal luggage, extra fuel tank and spare wheel carrier at the back. A visit to a weighbridge should confirm your fear or delight. My D4 weighs in at 1420 kg on the rear axle with stock standard, no luggage, only driver and 60 litres of fuel in original tank.

[Redback]

I have the 160ltr long range tank in the D4 2.7L, I use the fill the car and work out the Litres per 100 on how many litres I put in, there's more important things to worry about than few Ks here and there.

I drove to Shepperton a couple of weeks ago, round trip recorded 10.6/100 on the fuel thingy, when we worked it out after refilling the car with litres put in verses Ks travelled, 11. something, I'm happy with that considering the weight of the car and it's shape(a brick) if you want fuel economy, buy a Golf:burnrubber:

[dirvine]

All my previous cars have had a LR fitted. One of the reasons I did not fit one to the D4 was exactly what StewG states. Also this is reinforced with comments made by Redback on the penalty the fuel extra weight makes on fuel consumption. You will see I have a few mods which do effect fuel consumption, and yet on a country trips similar to driving to Shepperton, I get high 8/100 to low 9/100 depending on wind conditions. IMHO there are only a few times where I could see I (and I repeat I) would really appreciate the extra fuel carrying capacity. YMMV depending on where you go. Have done all the long remote trips in previous vehicles I no longer have the urge to do them again in this vehicle. When towing my off road van, I carry 60 ltrs on it, and have never been short of fuel.... mind you only have done 800kms between fills. But just evaluate where you want to go and do you really need that extra weight and the penalties it incurs on your vehicle. Maybe the cost does not justify the penalties imposed.

[Stuart02]

6.8/100 on a hwy run anyone? [emoji13]https://uploads.tapatalk-cdn.com/20210420/3779899af0d9b7dc46665882f808f6f2.jpg

[Tombie]

6.8/100 on a hwy run anyone? [emoji13]https://uploads.tapatalk-cdn.com/20210420/3779899af0d9b7dc46665882f808f6f2.jpg

Downhill from the servo hey [emoji851]

[Stuart02]

Downhill from the servo hey [emoji851]Downhill with a tailwind and slipstreaming!! That was Geelong bypass to Melbourne outskirts. Was still showing 7.4/100 when I hit the CBD!

[Stuart02]

Downhill with a tailwind and slipstreaming!! That was Geelong bypass to Melbourne outskirts. Was still showing 7.4/100 when I hit the CBD!And I should add, AT tyres, roofrack, and 242000 on the clock...

[rapserv]

All my previous cars have had a LR fitted. One of the reasons I did not fit one to the D4 was exactly what StewG states. Also this is reinforced with comments made by Redback on the penalty the fuel extra weight makes on fuel consumption. You will see I have a few mods which do effect fuel consumption, and yet on a country trips similar to driving to Shepperton, I get high 8/100 to low 9/100 depending on wind conditions. IMHO there are only a few times where I could see I (and I repeat I) would really appreciate the extra fuel carrying capacity. YMMV depending on where you go. Have done all the long remote trips in previous vehicles I no longer have the urge to do them again in this vehicle. When towing my off road van, I carry 60 ltrs on it, and have never been short of fuel.... mind you only have done 800kms between fills. But just evaluate where you want to go and do you really need that extra weight and the penalties it incurs on your vehicle. Maybe the cost does not justify the penalties imposed.

Swings and Round-a-bouts!
What you say is correct .. however .. some of us are actually living/driving in remote areas and access to fuel filling points can be be few and far between as well as quite costly .. eg. $2.00+/L.
Also, because you have a LR tank fitted ... doesn't mean you HAVE to fill it.
I for one, don't like the idea of carrying extra fuel in jerry cans ... especially on the roof!

[Tombie]

Swings and Round-a-bouts!
What you say is correct .. however .. some of us are actually living/driving in remote areas and access to fuel filling points can be be few and far between as well as quite costly .. eg. $2.00+/L.
Also, because you have a LR tank fitted ... doesn't mean you HAVE to fill it.
I for one, don't like the idea of carrying extra fuel in jerry cans ... especially on the roof!

I regularly did a trip that I couldn’t return without additional fuel on board.

Either had a 180km detour additional to the trip or ran out 80km shy of the nearest refuel point.

Additional tank fixed that.

And fuel was over $2.00/l back then.

[mowog]

I have the Long Range Tank with a pump so you need to do the transfer manually. I normally start a transfer at half.

I gave up long ago caring about how much fuel it uses. Just love driving it. If fuel consumption was important I would buy a small car...

[Tombie]

Same… I do back of the envelope calcs only.

Holds X litres, gets Y km/l
Add a safety factor depending on the terrain / load.

And go!


I’m switched on enough to see if it suddenly starts chewing significantly more, and then seek out the reason.

Other than that I don’t give a rats backside that on Tuesday, during the full moon I got 11.8/100km [emoji41]

[John_D4]

on Tuesday, during the full moon I got 11.8/100km [emoji41]
The full moon alters fuel economy? [emoji48]

[dirvine]

Swings and Round-a-bouts!
What you say is correct .. however .. some of us are actually living/driving in remote areas and access to fuel filling points can be be few and far between as well as quite costly .. eg. $2.00+/L.
Also, because you have a LR tank fitted ... doesn't mean you HAVE to fill it.
I for one, don't like the idea of carrying extra fuel in jerry cans ... especially on the roof!

But the penalty of LR tank is not just its weight empty or full, but also the weight of the RWC. This extra weight then needs to be taken into account when weighing GVM and GCM when towing. Even if you pay $2 per litre as opposed to $1.40, then count the extra fuel used lugging the weight around )(empty or full) the savings are not great and the pay back time is considerable. Yes I have used one and needed one when I did the Canning and Balfours, and you may well justify it. As I said not for me. I often think (and I am not saying anyone here does do it) that because others have this or that modification, I must have it as well without weighing up the reality of do I really need it?

[Tombie]

The full moon alters fuel economy? [emoji48]

Absolutely….

When the moon is full it imposed more gravity upon us. If your driving towards it you’ll get better economy, if your can see it in the rear view mirror it’s like towing as it imposed a resistance to your progress.

I thought everyone knew that [emoji41]

(Another tip for better fuel economy is to change to winter air in your tyres. It’s getting cooler in the mornings and summer air just doesn’t cut it.)

[Tombie]

But the penalty of LR tank is not just its weight empty or full, but also the weight of the RWC. This extra weight then needs to be taken into account when weighing GVM and GCM when towing. Even if you pay $2 per litre as opposed to $1.40, then count the extra fuel used lugging the weight around )(empty or full) the savings are not great and the pay back time is considerable. Yes I have used one and needed one when I did the Canning and Balfours, and you may well justify it. As I said not for me. I often think (and I am not saying anyone here does do it) that because others have this or that modification, I must have it as well without weighing up the reality of do I really need it?

Show me the fuel penalty….

My vehicle gets the same economy now that it did without. The only penalties imposed came from the Bar and Roof rack.

Payback is not a factor - convenience is.

[John_D4]

Absolutely….

When the moon is full it imposed more gravity upon us. If your driving towards it you’ll get better economy, if your can see it in the rear view mirror it’s like towing as it imposed a resistance to your progress.

I thought everyone knew that [emoji41]

(Another tip for better fuel economy is to change to winter air in your tyres. It’s getting cooler in the mornings and summer air just doesn’t cut it.)

That makes sense, I’ll go to the tyre shop in the morning

[dirvine]

Show me the fuel penalty….

My vehicle gets the same economy now that it did without. The only penalties imposed came from the Bar and Roof rack.

Payback is not a factor - convenience is.

So Tombie carrying weight has no penalty? Lets all drive around with fully loaded up cars. And to make it even more realistic lets just add 3.5t low profile trailer (so there is no wind drag behind) and we can all get the same fuel economy!!!Come on get a grip. (sorry you might have a problem with one of your hands).

Also for some payback V convenience is a factor for some as my post did say, it is. For you its convenience and bugger the cost. For me the very few times its an inconvenience is far outweighed by the cost.

[Tombie]

So Tombie carrying weight has no penalty? Lets all drive around with fully loaded up cars. And to make it even more realistic lets just add 3.5t low profile trailer (so there is no wind drag behind) and we can all get the same fuel economy!!!Come on get a grip. (sorry you might have a problem with one of your hands).

Also for some payback V convenience is a factor for some as my post did say, it is. For you its convenience and bugger the cost. For me the very few times its an inconvenience is far outweighed by the cost.

My fuel burn with the tank in and full is indistinguishable to that without. Always has been. There are way too many other variables to impact upon consumption.

The same 800km trip I’ve done countless times can see fuel burn as low as 10.1 and as high as 13l/100km. Almost always down to wind and traffic conditions. At least half those trips would be with the rear tank empty.

The weight penalty of 60kg of tank is not discernible on 3.08t of vehicle. My frontal presentation (drag), tyres I have on at the time and my right foot have far bigger influence.

[rapserv]

That makes sense, I’ll go to the tyre shop in the morning

.. and don't forget to pick up some extra blinker fluid while you're there![bigsmile1]

[DiscoJeffster]

.. and don't forget to pick up some extra blinker fluid while you're there![bigsmile1]

Thank god I got some before the WA lockdown.