How accurate is the computer?

[DiscoSaffa]

Perhaps a silly question, but was certainly front of mind when I was stuck in Sydney traffic this morning watching the carpooter count down the kms until my fuel ran out…….

How accurate is the computer’s range calculation and what margin of safety do they give you (ie once it says 0km how much fuel is in the tank)?

This morning when I FINALLY made it to the servo, the carpooter said I had 31km left to go, which based on this tank’s average consumption of 16l/100km I had about 5l of fuel left in the tank…… when I filled it up to the pump’s stop, I had put in 74l. Now if I am correct the tank size is 85l, which means the computer gives a “safety net” of around 5l for idiots like me that push the tank to the dregs on occasion…….

As an aside……. I tend to fill my tank past the pump’s first stop (with the V6 petrol you wanna get every drop in there!) and the filler pipe to the tank seems to hold about 6l of fuel which is good for a few spare kms……..

[gps-au]

I can remember watching it read "0 km" a few weeks ago when starting, then 5 minutes later it was reading "121 km".

Ok, I was parked overnight with the front facing downhill if that made any difference.

Before the longranger tank went in, i could fill to top and fit around 90 litres in, now I fill to top taking many minutes and the max I have managed to put in (combined tanks) is 198 litres (and it wasn't quite empty).

So far the max I have run with "0 km" showing is 87 km till first cough :angel:

[WhiteD3]

Mine's the same. Had lots of scares thinking I'm on the brink of being out of fuel only to find there was 10 litres or so in the tank.

I think the carputer reads economy 1l/100km better than actual, but this would mean you'd have less fuel, not more. Go figure!

[DiscoSaffa]

I can remember watching it read "0 km" a few weeks ago when starting, then 5 minutes later it was reading "121 km".

Ok, I was parked overnight with the front facing downhill if that made any difference.

This morning while crawling in traffic, going up or down hill made about 5km difference to the reading......... up = less, down = more....... so I gather the sensor is at the front of the tank........

[Bushwanderer]

I think that you are about right with the 5L="empty" guide, but remember the fuel pump uses the surrounding fuel to keep it cool. If you run it lower, you risk overheating the pump.

Hi DiscoSaffa, no there are two sensors.

[DiscoSaffa]

I think that you are about right with the 5L="empty" guide, but remember the fuel pump uses the surrounding fuel to keep it cool. If you run it lower, you risk overheating the pump.

Hi DiscoSaffa, no there are two sensors.

Two sensors...... interesting..... what about fuel take off? Not that one should be doing anything to hairy off road with an empty tank, but where is the fuel take off positioned in the tank?

With respect to the cooling, again interesting...... I tend to try and not run to lower than a quarter tank as a rule, sludge etc etc..... but every so often needs must..... you think they would warn you about something like this in the manual..... Blew a pump in my Flandy back in the UK, wonder if this is what killed it?

[87County]

Hi Discosaffa, in most cases of fuel tanks, (whether they are in planes, boats, trains or cars) the "usuable" amount is usually going to be less than the total tank capacity.

In other words, there will usually be some fuel that cannot be accessed by the pump.

So, perhaps, you were very close to that unrecoverable amount when by sutracting the amount put in from the tank capacity, you found you had 5 litres.

Another point does arise, and that is that many service station pumps over-read (gives the business a little profit margin), so in fact you may have had slightly more than your calculated reserve

FWIW, for peace of mind, I like to have something on the gauge and so top up when convenient in regard to price etc :)

[jtonline]

My carputer (V6 petrol) was saying 16kms, and when I filled it I put 80L in the tank! I was wetting myself as I was stuck in traffic just watching the carputer say 40km, 30km then 21km till empty and I had only travelled 400m! I don't risk it, get to eight Km's just stop and put fuel in.

[rmp]

The carputer works out range based on recent fuel consumption and fuel remaining. If you spend an hour idling in traffic then hit the freeway your fuel consumption (l / 100km) will drop and thus you will see your range increase. The reverse situation would see your range decrease much quicker than the distance you travel.

While the D3 has an 85l tank (or thereabouts, it does vary on models) the fuel warning comes on at I think 80km. A conservative 80km. Also note that you can, like most cars, get another 5-8l in if you trickle-fill till you see the fuel almost slop out of the filler.

The angle the car is parked at will make a difference to the fuel reading if the tank is partially full.

Cold cars use more fuel than warm ones so fuel consumption will drop as you move off and warm up, and range will increase.

Fuel consumption readouts are in my experience invariably optimistic, eg reporting 11/100 when in fact it is 11.5 or 12.

You don't ever want to run out of fuel on a modern car.

[drivesafe]

In both my rangie, I’d say every 4th or 5th tank, I would take the range below 10 KMs before fuelling up and never had a problem.

On a trip out west in the D3, I had planned to get some fuel at the top of Cunninghams Gap only to find the servo closed so I pushed on to Warwick and as the range kept falling I decided to drive till I ran out so I had less distance to walk.

I ended up driving the last 4 Ks with the range showing “0” and when I filled up, I still had at least 3 Lts in the tank.

I think you will find they probably have a builtin safety margin.

[DiscoSaffa]

You don't ever want to run out of fuel on a modern car.

You raise an interesting question..... I am well aware of the implications of running out of fuel in a diesel..... but what are the implications of running a D3 V6 Petrol dry? :confused:

[Tombie]

You raise an interesting question..... I am well aware of thh implications of running out of fuel in a diesel..... but what are the implictaions of running a D3 V6 Petrol dry? :confused:

A dead fuel pump from running without fuel to cool and lubricate it.

[DiscoSaffa]

A dead fuel pump from running without fuel to cool and lubricate it.

which is not good..... so does the pump just die? and what is the process for start up should one run out? bearing in mind one wants to protect ones cats from any blow back etc etc etc.......

sometime think i should trade Audrey in for a Series 1........

[jonesfam]

And where is the hand pump on the TDV6? Or is there a hand pump on the TDV6? No mention in the manual & I can not find it.
Every diesel I have ever owned had 1 including 2 X common rail (mind you the Pathies was not usable due to it's location), is this something LR have dispensed with?
Jonesfam