D40 Fuel Economy

[Old.Tony]

Cheers for some enlightenment. Mine doesn't have a display to tell me what my vehicle's ECU is calculating. The salesman told me when I ordered mine it would be exactly the same as the twin cab display and demo models on the car lot, except it would be a king cab.

So I just assumed, because I have a late 2012 model that cost north of $50k new and it doesn't have a trip computer, that no 2.5 litre models had them, so it didn't occur to me that someone would assume I meant trip computer when I said trip meter.

The Spanish models (VIN starts with 'VSK' got a trip computer as well, which is vaguely accurate. It can be fooled fairly easily, unfortunately.

The absolute best method for working out consumption is the method you described, but I've been having some success by watching my instantaneous litres per hour (not litres per hundred km) and keeping that as low as possible. This information isn't available on the dash, I get it from the ECU using a bluetooth dongle on the OBD port and the Android app "Torque".

 

[nathand22]

I thought to calculate fuel consumption all you had to do was work out the number of litres used over a 100km, and I don't recall seeing it expressed in any other way for many years here in Australia. I reckon my tripmeter/odometer is accurate enough for the distance and the diesel bowser accurate enough for the amount of fuel used.

I just can't understand people saying this is the wrong way to do it and there are more variables to take into account in the initial calculation.

If you are running different size tyres then standard like 32's for eg then not only is your speedometer changed but so is the odometer, so you would need to calculate how much that has changed the odometer reading to accurately wok out the true fuel consumption.
That may be the extra figures people are having to do.

 

[Old.Tony]

^ Spot on the money. I've posted my formula for it before, you have to multiply the km travelled by the percentage increase in rolling diameter (and I have a method of calculating that as well).

 

[happy john]

Not Navara related but the Amorok that did a run today with the scouts returned an average of 7-8 lph. This is going over Cunninghams Gap not towing with about 150kg in the tray. The old 22 was on 10-11 lph with a medium foot. And despite the vw quoted figures that little motor is slow and has to be revved to get going. Not to mention the poor clearance.

 

[joe2006]

Achieved a personal best yesterday.

......................Drum roll........ 29.14lph towing the van into a stiff headwind. Only sitting on 75-80kph too.

Up to that point, my average lph was significantly lower than following the same route this time last year.

The calculations are done manually at each fill.

The next tank was 13.25lph, albeit with the same wind pushing from behind.

 

[happy john]

That's a remarkable but understandable difference Joe,have you also found sometime particularly out west the road has just a slight uphill gradient and you look at the gauge and think wtf. I had the same issue as you near Rockhampton head wind on the way up tail wind back sitting on 90.

 

[joe2006]

Yeah John and sometimes your eyes play tricks on you, well at least mine do. What looks up is sometimes down and visa versa.

At least I was not on my own. Anybody that went in the same direction as me yesterday was complaining about the horrendous fuel consumption.
One bloke I spoke to said that he stopped his Jeep and checked that the vans handbrake was not on.

 

[Old.Tony]

We had a run like that from Wilcannia to Cobar. Couldn't get the car to stay in overdrive, so the TCC just wouldn't lock, revs stayed high, and it was driving me spare. We had to refuel in Cobar - from there on we had a much better run, and I put it down to a bad load of fuel from the Shell in Wilcannia.

I'm not sure that's the case - at the time, I was not very experienced with a diesel auto having only driven 8290km in one when I filled at Wilcannia. We've been that way a couple of times since and faired much better, although the next time we go out that way we'll be towing 700kg more (with more frontal area too - greater wind resistance).

 

[happy john]

Yeah John and sometimes your eyes play tricks on you, well at least mine do. What looks up is sometimes down and visa versa.

At least I was not on my own. Anybody that went in the same direction as me yesterday was complaining about the horrendous fuel consumption.
One bloke I spoke to said that he stopped his Jeep and checked that the vans handbrake was not on.

Silly me in a hurry to leave left the handbrake on. I only drove 2 k's and the van was an anchor. But off topic these things happen.

 

[Nate_obyrne]

Hi guys I have a 2008 d40 extra cab auto and am only getting 300ks to a full tank not towing but with tools in the tray. I've had the computer checked and apparently it's all ok. I need help or I'm going to have to try sell it!!!

 

[Old.Tony]

King Cabs are known for this. Resetting the thing doesn't help a lot, but we've had a couple of people say that their Nissan dealer had put an updated program into the ECU which fixed the fuel consumption issue. Unfortunately we can't get anyone to tell us what the TSB number for this fix is, so we don't know what to tell you to ask your dealer for.

 

[camo.b]

Hi guys I have a 2008 d40 extra cab auto and am only getting 300ks to a full tank not towing but with tools in the tray. I've had the computer checked and apparently it's all ok. I need help or I'm going to have to try sell it!!!

There was a problem with the older auto kingcabs..im sure there is a computer update to fix it..and im sure there ir a post or 4 about it on here.

 

[scarecrow73]

I own a Sept build 2013 ST dual cab auto and so far for the 6,500 km's travelled I'm averaging 10.95 L/100 km. My last fill tonight netted 12.17 which was all city driving. I haven't managed to give it a good long run as yet but next month planning a trip to Tahlia SA for some salmon fishing so hopefully will get a better figure for that one. Still running OEM tyres (HT's) with ARB bullbar and canopy. Hoping figures will go down but the graph for the past few fills is on the way up.

And whats with the fuel guage?? Most I've managed to get in is 72L when showing empty. I know they aren't too accurate but surely taking the pi55 a bit��

 

[joe2006]

I ran out of fuel a couple of weeks ago and got 77.6 litres into the tank. It is possible that there may have been a bit left in the tank and I picked up a bit of air when in motion. Either way it doesn't make it 80 usable litres.

Not that I should be one to talk, but watch running the fuel down too low because it has been reported that the fuel pickup has been starved of fuel when parked on a hill, with quite a few litres still left in the tank. I think nose down was the problem?

 

[camo.b]

Nose up in the driveway did it to me joe2006

 

[joe2006]

Maybe I should change my post to nose up?

Edit: After reading Nath's post (below), best I leave close enough alone.

Oh and my fuel light was on for ages before running out. Just couldn't get to a town with fuel quick enough and ended up rolling about 10 meters short of the bowser. Before filling, the primer was hard after a few pumps so that is why I figured that it is likely that there was a little more fuel in the tank.

There was and still is 60 litres of jerry cans in the back in case of a real emergency!

 

[nathand22]

It happened to me with the nose down in a mates driveway and the fuel light hadnt even come on.
It also did it to me going down a long hill on the freeway and the fuel light had only been on for less then 20km and from experience the light comes on with anywhere between 12 and 17lts in the tank.
I actually rolled to the bottom of the hill got out and primed it, then drove the rest of the way to the servo that i had planned on stopping at.

From my experience its allot worse when pointing down hill, but as the pick up is basically in the centre of the tank it can and obviously does happen either way.

 

[TroyMac]

Wow this is crazy what some people are getting out of there tanks. I just brought a 2011 D40 dual cab auto with just under 40,000kms and out of the 65 litres used I managed to get only 480km which equals to 13.54L/100km! Though it is due for a service soon and it does have a bullbar and All-terrain LT265/75R16 but I think it still should be a bit better.

Will probably try that EGR blocking mod soon and see if that might help. Also does any one know the stock wheel size for the D40?

 

[Old.Tony]

Stock wheels on my 2009 are 255/70R16, I'd say yours should be the same. I think the 2012 models came with 17" rims.

13.54LPHK is a bit high, especially if yours is the Spanish (the VIN starts with VSK) model with the 140kW engine. Your tyres are about 5% bigger than standard and will cause a little more fuel consumption (as well as loss of power) but you've gained a little in height. You should adjust your km by this variance - it means you've actually done 505km and that means you've used 12.87LPHK (still higher than I'd expect).

Couple of things you could do:

1) Clean the MAFS
2) Run some Liqui Moly injector cleaner through a tank
3) Consider accelerating with your RPM between 2500 and 3000 so that you're closer to the torque converter's stall speed (less losses in the transmission).
4) Above 70km/h, always stay in 'D' (indicated on the dash) and allow the torque converter to lock as much as possible. At 80km/h you should be doing about 1500rpm.

 

[TroyMac]

Stock wheels on my 2009 are 255/70R16, I'd say yours should be the same. I think the 2012 models came with 17" rims.

13.54LPHK is a bit high, especially if yours is the Spanish (the VIN starts with VSK) model with the 140kW engine. Your tyres are about 5% bigger than standard and will cause a little more fuel consumption (as well as loss of power) but you've gained a little in height. You should adjust your km by this variance - it means you've actually done 505km and that means you've used 12.87LPHK (still higher than I'd expect).

Couple of things you could do:

1) Clean the MAFS
2) Run some Liqui Moly injector cleaner through a tank
3) Consider accelerating with your RPM between 2500 and 3000 so that you're closer to the torque converter's stall speed (less losses in the transmission).
4) Above 70km/h, always stay in 'D' (indicated on the dash) and allow the torque converter to lock as much as possible. At 80km/h you should be doing about 1500rpm.

Nah its a Thai made I think (VIN:MNT). And yeah I'll try all that after I get it serviced and see what the mechanic thinks as well. And as for the RPM I am roughly around 2000 to 3000 on take off, but ill start to aim between 2500 and 3000.

Haha sorry for the silly question but I thought the 'D' stood for drive ?