D40 Fuel Economy

[nathand22]

I don't know guys, those figures some of you are getting are amazing. This Navara never went below 20's since new, usually average 22L, regards if driven around town or country, can't believe it.

If you are only getting 20-22lph something is wrong mate.
i have had my d40's fully loaded with a fully stacked gal off road camp trailer with enough stuff four 5 people and towing on sand with better figures then that.
we travelled around 850km on Fraser at xmas including towing obviously all on sand and in 4x4 with super low tyre pressure and returned around 14-15lph

 

[user 10312]

Seriously wrong, with those sort of figures it would be throwing brickets out the exhaust.

 

[Old.Tony]

I don't know guys, those figures some of you are getting are amazing. This Navara never went below 20's since new, usually average 22L, regards if driven around town or country, can't believe it.

Unless it's a petrol engine and you're trying to tow a bus with it, there's something wrong with those figures.

That's going to be either the method of calculation, or something drastically wrong with the motor - and unless we get the method of calculation right, we won't know if it's appropriate to look at the engine/fuel system.

So, next time you go and fill up, reset one of the trip meters. The right-hand instrument panel knob can be pressed quickly to make it change between trip meters, and held for 3 seconds to reset the currently visible trip meter.

Use the vehicle as normal then fill up again, noting the litres and km (I write the km travelled on my fuel receipt) then post these two figures here.

 

[jimmy_jay89]

i found it odd that im getting about 8.4-9.2Lt/100km

no mods but getting excellent economy

 

[Old.Tony]

I've just done another acceleration test logging the fuel flow rates etc. Here's the result:

Accelerating while keeping the RPM around 2,000:
- used 68.6ml of fuel
- took 22.94 seconds to reach 58km/h
- travelled 258.9 metres to reach 58km/h

Accelerating while keeping the RPM between 2500 and 3000:
- used 57.08ml of fuel
- took 13.23 seconds to reach 58km/h
- travelled 122.92m to reach 58km/h

Certainly seems like getting into the higher HP range, and the torque converter stall zone, plays an important part in our fuel economy.

 

[siringo]

I've just done another acceleration test logging the fuel flow rates etc. Here's the result:

Accelerating while keeping the RPM around 2,000:
- used 68.6ml of fuel
- took 22.94 seconds to reach 58km/h
- travelled 258.9 metres to reach 58km/h

Accelerating while keeping the RPM between 2500 and 3000:
- used 57.08ml of fuel
- took 13.23 seconds to reach 58km/h
- travelled 122.92m to reach 58km/h

Certainly seems like getting into the higher HP range, and the torque converter stall zone, plays an important part in our fuel economy.

Wonder if it's any different in a manual. Did you use Torque Tony?? If so, what settings/readings did you use??

 

[Old.Tony]

Wonder if it's any different in a manual. Did you use Torque Tony?? If so, what settings/readings did you use??

Torque is the app. I wrote to the developer and I should eat some humble pie, because what I wanted to do was already built in to the app and I should have RTFM first.

At the main menu, open the menu and choose 'Settings'. Select 'Data Logging' then the first option is 'Select what to log'. Bloody obvious when I saw it, and I can't thank Ian Hawkins enough for not chewing my head off for being a dumbass and not having a decent look for the info first.

Once you've chosen your items, while you've got the 'Realtime Information' being displayed, open the menu and stop/start logging (second option from the top). When you've got all your data, email the logs to yourself. I use CSV format then apply formulae to better interpret the data.

 

[jimmy_jay89]

i might do this later then

 

[Pete22]

I don't know guys, those figures some of you are getting are amazing. This Navara never went below 20's since new, usually average 22L, regards if driven around town or country, can't believe it.

My consumption has never been that bad but I too fail to get the figures being quoted above. My consumption history is here: http://www.fuelly.com/driver/pete22/2008-d40-dual-cab-ute

 

[redhotnavara]

It's been checked numerous times, litres filled against kilometres travelled. It was at the dealers a couple of times with the consumption complaint but they said it was normal as I had a 2" lift, muddies, ARB bar, canopy and roof racks. I can't understand how you can get such poor economy from a 4 cylinder diesel but I just gave up, no one to turn to, that's why I'm posting here.

 

[KraftyPg]

Certainly seems like getting into the higher HP range, and the torque converter stall zone, plays an important part in our fuel economy.

That may be true however it's still ideal world testing. Economy still comes down to an entire trip not just how quick you take off, but the impracticability of taking off at that speed all the time must surely increase the economy more than any saving that one such test was able to prove.

If you push one of these things to 2500 rpm every time you take off from either a stop or from a slow down at an intersection in many cases you'll find yourself going accelerator brake accelerator brake, which is not productive on fuel or brakes, whereas taking off slower and cruising to the next intersection could well save more fuel and wear and tear.

On longer runs between start and stop getting up to speed could possibly save fuel but given most of us spend alot of our time in 40,50, 60 and 70 zones again it appears there is no one single proven method that will work for everyone.

 

[Pete22]

I beg to differ Pete, I'd have the same or similar weight as you. I have 265 75 r16 tyres and I can get anything from 8.9-13lhk around town!! Even more consistent on the highway...

Is your ute auto or manual Mike?

 

[mike1303]

It's a six speed manual Pete.
I averaged 10.8 today driving from job to jobs.
I also have a chipit, forgot to mention!

 

[Old.Tony]

That may be true however it's still ideal world testing. Economy still comes down to an entire trip not just how quick you take off, but the impracticability of taking off at that speed all the time must surely increase the economy more than any saving that one such test was able to prove.

If you push one of these things to 2500 rpm every time you take off from either a stop or from a slow down at an intersection in many cases you'll find yourself going accelerator brake accelerator brake, which is not productive on fuel or brakes, whereas taking off slower and cruising to the next intersection could well save more fuel and wear and tear.

On longer runs between start and stop getting up to speed could possibly save fuel but given most of us spend alot of our time in 40,50, 60 and 70 zones again it appears there is no one single proven method that will work for everyone.

Absolutely. And one of my next tests will measure fuel flow rate, speed, engine RPM and distance travelled. The idea being to see how much fuel I use to cover a whole kilometre for both methods of getting the vehicle up to "cruise" which I've tried at both 50km/h and 60km/h.

I've got to find a fairly flat section of road where I can do this without too much interference from traffic - I'm looking for a base line, or a "this is the best economy if nothing else interferes" kind of measure. It's obvious that other traffic is going to make it worse, and that sometimes coasting is all you need to do because the next set of lights is already orange, but if there's a base that we can establish that says "THIS method of driving provides better economy under ideal conditions" then those who are getting dismal figures can try it and see what happens.

 

[flashum1]

Mines 09 2.5 manual, lifted with mud terrains, 3" exhaust with dump pipe, airtek snorkel, single mass flywheel upgrade, steel bullbar and rhino roof platform on canopy. Us usually just shy of 600 km around Brisbane (even mix of highway, city, traffic before light comes on and usually takes around 71 litres. I'm ok with that but now towing 23ft van at around 2.5 tonne I think I'd be lucky to get 400km. Went from ballina to Glen innes covering 290km of pretty nasty hills and it took 56.5 litres to bring back to full. Does that sound right?

 

[Old.Tony]

Flashum, that's 71/6= 11.83 LPHK for city driving which is not bad at all. The hilly drive with the van on the back wasn't unreasonable either - 56.5/2.9 = 19.48LPHK and for hills pulling 2.5T on your ass is not too bad. What speed did you cruise at while towing?

 

[Pete22]

It's a six speed manual Pete.
I averaged 10.8 today driving from job to jobs.
I also have a chipit, forgot to mention!

Therein lies the difference Mike the autos are much more thirsty than the manuals.

 

[flashum1]

Flashum, that's 71/6= 11.83 LPHK for city driving which is not bad at all. The hilly drive with the van on the back wasn't unreasonable either - 56.5/2.9 = 19.48LPHK and for hills pulling 2.5T on your ass is not too bad. What speed did you cruise at while towing?

Where I could I was sitting on 110, usually in 5th at around 95-100, tends to get a bit scared by hills understandably! Should be heaps better I hope when chip-it sort out dramas with dominator and supply it, been waiting over 2 months now, really anxious!

 

[Old.Tony]

Where I could I was sitting on 110, usually in 5th at around 95-100, tends to get a bit scared by hills understandably! Should be heaps better I hope when chip-it sort out dramas with dominator and supply it, been waiting over 2 months now, really anxious!

Once you put a chip in, the torque curve could move. That affects your ideal (for economy) cruise speed.

A standard D40 engine cruises at 2,000rpm - this is the point at the END of the steep torque climb. Below this point in the RPM range, you're not developing as much torque as you could, and beyond it you're throwing fuel at it in increasing quantities for an amount of torque that isn't increasing as quickly.

I've found that at 110km/h I'm using about 2LPHK more than I would at 95km/h (based on numerous highway runs of 10 hrs+ duration).

 

[flashum1]

Yeah but doesn't like 95 in 6th, worried that cruising in 5th all the time would result in more fuel burn?