D40 Fuel Economy

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Gentlemen,

I have just spent the past hour reading every post on this 32 page thread trying to find an answer.

I've got a '08 D40 T/D Auto STX DPF Fitted (Spanish Built) and I am getting absolutely fed up it with its fuel consumption and would really appreciate some solid advice. Some info to consider:

1. Only addition to weight would be my ARB Sahara bull bar
2. 25,000km on the clock running the stock Continental CONTITRAC 16' Tyres
3. Driven mostly to work and back during week (15km each way) and the ocassional weekend drive to visit family/friends (50-100km) max
4. I work at a Caltex Servo (Truck Stop) so i've only ever filled up with Caltex Diesel.
5. Serviced strictly every 5,000km using C3 oil + new filter - have also replaced air & diesel filter (genuine)

Fuel consumption has been getting worse and worse. 410km and the light comes on. I estimate at that rate that i would get about 480km out of an 80 litr tank... 16.6L/100km constant.

Have tried the ecu reset. Has done nothing. Gave it to Nissan.... gave me the usual response. "Have checked the system (ecu) with no errors.

What to do???

Only advice I can offer is when the low fuel light comes on, It represents you have approx 16L left, You'll need to add that into the equation.
 
I would dare say that at 15k each way the engine would only just be starting get up to temp
at 25000 the engine would not be free enough to give you good returns

however you should be doing better than your getting , you can get aftermarket DPF pipes now from Chipit.com.au dont know how much

How are you resetting the ECU ???

Disconnect your battery, next try to start your engine , this will drain all back up power from the ECU , reconnect battery and your done

see how that goes for you

Marty
 
When you did the ECU reset, did you immediately take it for a gentle drive? It has become apparent that taking the vehicle for an unladen, gentle (minimal fuel usage) drive is quite important - try to keep the RPM under 2500.

Stop-start traffic is a killer for any vehicle, and the more weight the worse it becomes. My Jaguar (XJS, V12 5.3L) would go 250km on a 90L tank around town, and would use about 20L of fuel to get to Sydney (170km).

I've found our diesels are similar. Mine weighs 2.5 tonne usually, with all the stuff I have in the tub, its canopy, bullbar, winch and occupants. Around town, if I try to drive it like everyone else drives their petrol cars, I find that I'm really throwing the fuel away. If I just take off normally, not letting it rev over 2500, minding my own business, then things improve, but the stop-start still hampers good economy.

When we hit the highway and go for our drives, the thing shines as long as I keep the speedo needle under 100km/h (tacho @ 2,000rpm). This is the point where the turbo boost and engine RPM combine to provide the onset of maximum torque, and beyond the 2,000rpm mark you're using more fuel to get less and less power. Then you add the exponential rise in wind resistance and you basically get the equation that 2,000rpm is the ideal cruise spot, get there and stick to it even in a 110k zone.

Part of it is car, part of it is fuel, part is environment and part is driver.

And for me, back in October last year, ALL of it was a learning experience. The lessons, for me, still continue.
 
Work further from home. I don't even think your car would warm up in that time. I would suggest doing a long trip, half a tank in each direction after doing a ecu reset. That will at least give you a real indication of consumption, instead of 15km to work and back. Try not to push over 2500 rpm on you trip and see how you go.

My guess would be your problem is that 15km drive and back. Diesels are long distance runners not sprinters
 
2010 stx auto diesel, 110k's on clock, computer was saying 16.8L/100km's when I picked it up with 34 km's on the clock. I reset the fuel economy counter and it now reads 10.8L/100km's was reading 8.9L/100km's for a while on the highway then I drove around town for about 10 k's. will see what happens and keep ya all posted.
 
I have a long range tank holding 150lts... 2.5 6 speed getting about 1100km with 10lts still in tank.
My car has a lot of stuff on it though. Front cover custom utes mag this month.
Also only has 3500km on the clock so I hope it will get better!!
 
stewiebri

I get over the 700 km mark before the fuel light comes on, usually comes on between 720 -750km's thats around town/city and odd runs off with the bike on the back.

08' Stx 2.5 TD manual 6 speed

i had an stx auto v6 for 67000 klms and was getting 11.5-12.5 klm/100k on the highway,driving for economy 100/110 kph,but heavy on the juice around town 14.5- 17l/100 the final straw was towing a hire trailer 250 kg load airlie beach to gladstone 26l/100. i traded for stx 2008 auto diesel ,very disappointed 11.7 hwy 14-16 city 12.7 combined in 57000klm. drive my 04 vw transporter in preference3 or 4 l/100 better fuel economy,and more grunt. cheers s
 
Hi everyone, I have owned a D40 Navara for around 6 months now and was wondering what other owners were getting on fuel economy around town?

Hi Dazza ,im getting 570 to the tank on d40 2.5 2008 mod .
im carrying tools as well.
 
my d40 is getting 15l/100kms when stock went to nissan and they said its with in average apecs wasn't very happy
 
Blue it's gotta still be a young 'un. Diesels take a little longer to bed in and they last a lot longer too. Mine didn't settle until about 13,000km.

You can try an ECU reset, and it's really easy to do.

1) Note your tripmeter figures, disconnect any trailer, unload the tub.
2) Open the bonnet and disconnect the BATTERY NEGATIVE lead from the battery
3) Press the brake pedal for 2 seconds
4) Return the battery negative lead to the battery and do it up well, close the bonnet
5) Take the vehicle for a gentle drive. Don't rev over 2500rpm, no steep hills, ignore the gorillas in the Fords at the lights.

See how that goes!
 
Have had my injector pump re flashed (so they told me could be a load of BS) but after that and with EGR valve blocked has brought figures back to 11l/100 combined.
 
Makes people laugh when l say lve got a d40

Guys l cant believe lve bought my first new car and its one of these ......good parts kids fit in the back ...... Bad parts rattles , fuel accom,sloppy gear change... lm a builder so no more than ten bags of concrete or the thing is on the rubbers...letting people drive it that dont know about starting off in first gear......,good things....it looks good
 
Thirsty, the rear springs are rated for something like 150kg. Putting 10 bags - 400kg - is bound to invert the springs!

Ironman apparently have a suspension support product that I'll be looking into instead of air bags. That way I can soften the suspension in a few minutes if I'm not loading up.

As for your economy, try unloading it and doing the ECU reset trick and see what that does for you.
 
Thirsty, the rear springs are rated for something like 150kg. Putting 10 bags - 400kg - is bound to invert the springs!

Ironman apparently have a suspension support product that I'll be looking into instead of air bags. That way I can soften the suspension in a few minutes if I'm not loading up.

As for your economy, try unloading it and doing the ECU reset trick and see what that does for you.

thanks Tony but 10 bags of render is 200kg ,but l will give the ecu thing a try thanks........
 
Thirsty, the rear springs are rated for something like 150kg.

I don't know that I agree with that.

Model-dependent, the D40 has a theoretical max payload of between 776kg and 1230kg - halve that and you have the design carrying capacity of one of the springs.

You'll never get a single number in kg/m for the spring rate of leaf springs - they have a progressive spring rate so you'll get a rating for each individual leaf.

When EFS sell "150kg constant load springs", they are marketing to those with vehicles with a constant load in the tray of 150kg - tools or a 180L long range tank or whatever - and supposedly the standard factory ride height and feel is restored as if you had no load.

The rubber bump stops are substantial on these leaf sprung commercial vehicles as the bump stops form another level of progressive springing. You'll notice that they are wedge shaped so even the bump stops themselves are progressive. You can actually drive around on these bump stops all day, and any load that is approaching the full payload will indeed do this. It's not overloaded, you have to use your judgement of the load you are carrying to determine this. If the bumpstops were not an intentional component of the rear suspension, the springs would be so hard everyone would refuse to ride in the vehicle unloaded.
 
I don't know that I agree with that.

Model-dependent, the D40 has a theoretical max payload of between 776kg and 1230kg - halve that and you have the design carrying capacity of one of the springs.

You'll never get a single number in kg/m for the spring rate of leaf springs - they have a progressive spring rate so you'll get a rating for each individual leaf.

I don't recall where I got that number from, might have been the dealer, might have been here - but the word was, if I wanted to put more than 150kg in the tub, I'd need to look at better suspension. Maybe I should have worded it like that!

I've no doubt that's at least close to correct, because with about 100Kg or so my leaf springs are inverted already (Engel, 2 deep cycle batteries, a Honda Eu20Si generator and about 30kg of other stuff).

I don't believe that stock out-of-the-factory, my Navara was capable of being driven at normal ride height with anywhere near the "maximum load". There's a pic of her in my garage with 180Kg of ball weight and a full tub, the tail is noticeably lower (taken at Ulladulla, NSW).

Sure the car might be capable of it, stock - and I could probably do it, riding around on the bump stops all day, but I'd rather not hit a pothole and have my ******* relocated next to my left ear!
 
Sure the car might be capable of it, stock - and I could probably do it, riding around on the bump stops all day, but I'd rather not hit a pothole and have my ******* relocated next to my left ear!

Hahahaha. I reckon the rubber rides quite smooth personally. The springs do still work just fine inverted. If the salesman told you you need aftermarket suspension to put more than 150kg in the tub of a 3/4T commercial vehicle, his job should be in the newspaper! :big_smile:
 
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