Thread: D4 Long Range tanks and fuel usage?

Nope!

You have the gravity fed tank I take it?

The computer can’t work it out.

Originally Posted by 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'.

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

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.

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?

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.

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.

Originally Posted by rocket rod

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.

Spot on Brad

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