D40 chewing excessive fuel?
- Thread starter Bright Spark
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When you are on the highway with an empty vehicle, how fast are you going? 11.7LPHK is quite reasonable if you're sitting on 110km/h.
You can get it lower by going slower. The sweet spot in the D40 is where your tacho is hovering around 2,000rpm.
ozsnow
Member
I had an 06 STX auto - on a highway trip sitting on the speed limit I could rely on 9 per 100, worst I ever got was towing a ski boat from Sydney to Jindabyne and that was about 16 (all recorded on the scan gauge). For the record the boat is about 1600kg.
The old nav had steel BB, 265-75/16 tyres, K&N filter and DP chip but no DPF
My new STX V6(only done 1600ks) is already doing better on fuel and certainly travelling faster!
Tappet
Member
I'm happy with my consumption taking it easy around town high 8 L /per/100K. 2011 King Cab.
As mentioned before just over 2 tonne of vehicle and as areo as a brick.
However once on the cruise wieght has only a small effect consumption. The main thing is wind restistance. For every doubling of speed the drag quadruples and force reqired (read fuel as well) to over come the restistance also quadruples.
As mentioned before just over 2 tonne of vehicle and as areo as a brick.
However once on the cruise wieght has only a small effect consumption. The main thing is wind restistance. For every doubling of speed the drag quadruples and force reqired (read fuel as well) to over come the restistance also quadruples.
Wow, 9 L/100 with an auto without DPF and those big tyres, I have only heard from a couple D40 auto owners pre DPF, that's quite a difference in fuel economy. After I put my 275/65/17 my figures went to 14l/100 blocked my EGR and did a reset and went to around 13 l/100, obviously full highway driving would bring it down even lower.
Hi Tony (and others)
I took the misses and kids away for a weekend to a resort. Hence, only a couple of bags of clothes. (i have to keep them happy sometimes!!) Most of the trip was at 100kph. Tacho sits at about 2100 to 2200rpm. I try to drive as fuel efficient as possible, but i think i will have to have it checked on the dyno. I Nav is still stock engine wise so i might look into removing DPF and EGR. Any other sugestions?
Thanks Jacko
K
KraftyPg
Guest
Define "fuel efficient" driving. What one person considers efficient may be totally different to what someone else does and neither could be efficient methods. (note that's not actually a directed question more a statement as comparing one person to another on the internet is nearly impossible)
Mine sits closer to 2000 RPM at 100kph so if yours is between 2100 and 2200 that easily explains a higher fuel usage to me, it may not be much but it will be a change.
How two drivers handle hills will make a difference, how two drivers handle stop starts will make a difference, there is so many varying factors that pin pointing one with limited information is not going to be a simple task. Even if a person was able to dot point all their driving techniques it still wouldn't be an easy task.
As for removing the DPF or doing the EGR mod, these may help but seriously there is enough people with DPF's or no EGR mod that are getting "reasonable" fuel figures that don't make either a magic bullet fix.
However I'd still suggest figures in the 11's might be on the higher side of normal but they are definitely in the normal range for many D40 owners on this site.
Mine sits closer to 2000 RPM at 100kph so if yours is between 2100 and 2200 that easily explains a higher fuel usage to me, it may not be much but it will be a change.
How two drivers handle hills will make a difference, how two drivers handle stop starts will make a difference, there is so many varying factors that pin pointing one with limited information is not going to be a simple task. Even if a person was able to dot point all their driving techniques it still wouldn't be an easy task.
As for removing the DPF or doing the EGR mod, these may help but seriously there is enough people with DPF's or no EGR mod that are getting "reasonable" fuel figures that don't make either a magic bullet fix.
However I'd still suggest figures in the 11's might be on the higher side of normal but they are definitely in the normal range for many D40 owners on this site.
+1 on Krafty's advice. that 100-200rpm difference is all it needs.
The torque curve climbs dramatically until about 2000rpm and from there it follows a fairly flat line as the revs climb. This means you're putting more and more juice in, but you aren't increasing the amount of torque.
That makes the point at which your vehicle is MOST efficient right on the 2000rpm mark. That should (on standard tyres) be somewhere around the 95km/h mark.
And yes, 5km/h does make a difference.
Still, (also as Krafty says), your car's not so far from "the norm" here that you ought to be worried that something is amiss.
The torque curve climbs dramatically until about 2000rpm and from there it follows a fairly flat line as the revs climb. This means you're putting more and more juice in, but you aren't increasing the amount of torque.
That makes the point at which your vehicle is MOST efficient right on the 2000rpm mark. That should (on standard tyres) be somewhere around the 95km/h mark.
And yes, 5km/h does make a difference.
Still, (also as Krafty says), your car's not so far from "the norm" here that you ought to be worried that something is amiss.
Thanks for all the advice.
Sorry, but i don't uderstand the technical side of the engine so i'll leave that one for the mechanic.
As for 'fuel efficient driving' I've had the car for a 18months now ( read many posts on this forum and found them very helpful. Thanks.) and had tried many different driving styles to test econemy and my best effort was 11.7 and the worst i did was 22.5 (sand driving not towing but that was expected). I have found that with my normal day to day driving (which is not far, 20km or so) i get between 15 and 16l/100k. I have had it down to high 12's but cant seem to work out why it is so high (in my opinion). My thoughts were leaning to the DPF.
K
KraftyPg
Guest
Is that driving city driving? City driving and city driving for short distances will always produce worse figures.
Going by the way the DPF works city stop start and short city could easily effect the number of times the DPF has to regen so in turn that could increase economy but the amount of fuel the DPF uses each regen is really not substantial enough to add several litres per 100km.
The DPF is something many people blame for bad economy but if it was me I'd be looking at other options before paying $800 (or whatever the going rate is) to remove the DPF. If you believe your driving style is not the culprit look at getting a major service done and having everything checked and maybe even tuned.
But realistically you are talking about a 5 year old vehicle not only has it had 5 years worth of running behind it but in 2009 when I brought mine Nissan's rated economy was something like 11lph, for a model that was released 2 years before that it wouldn't be surprising to see that Nissan was quoting 12's or higher.
It does pay to remember that even though we all have D40's with similar engines they aren't all the same, in 2010 they increased the power to 140KW and claimed nearly 1lph better economy. There is nothing to say they didn't do the same between the 07 of yours and the 09 of mine.
Going by the way the DPF works city stop start and short city could easily effect the number of times the DPF has to regen so in turn that could increase economy but the amount of fuel the DPF uses each regen is really not substantial enough to add several litres per 100km.
The DPF is something many people blame for bad economy but if it was me I'd be looking at other options before paying $800 (or whatever the going rate is) to remove the DPF. If you believe your driving style is not the culprit look at getting a major service done and having everything checked and maybe even tuned.
But realistically you are talking about a 5 year old vehicle not only has it had 5 years worth of running behind it but in 2009 when I brought mine Nissan's rated economy was something like 11lph, for a model that was released 2 years before that it wouldn't be surprising to see that Nissan was quoting 12's or higher.
It does pay to remember that even though we all have D40's with similar engines they aren't all the same, in 2010 they increased the power to 140KW and claimed nearly 1lph better economy. There is nothing to say they didn't do the same between the 07 of yours and the 09 of mine.
justdrinkbeer
Member
My King cab was doing around 18l/100km, tools, square boxes etc on all the time & 32" muddies, did the EGR block & it came down to 14l/100km, with a bit (little Bit) more poke too.
New one sitting around the 12l/100km around town, full of crap all the time and I do drag people off the lights most days, can't help it.
Worst i've seen was 65l/100km when I reset the computer thing then did a few km of steep muddy tracks in low range, didn't think i'd get out of that forrest!!!
New one sitting around the 12l/100km around town, full of crap all the time and I do drag people off the lights most days, can't help it.
Worst i've seen was 65l/100km when I reset the computer thing then did a few km of steep muddy tracks in low range, didn't think i'd get out of that forrest!!!
Mine's a 2009 auto with the DPF still intact. At Christmas (2011) we filled up the tank in Kotara (Newcastle) on Thursday night. Friday morning we drove to Melbourne, got on the Spirit of Tasmania that evening, and Saturday morning drove off in Devonport. We drove around a little then headed to Launceston where we refuelled - 1,118km for 120.91 litres or 10.60279LPHK. That's with 4 adults + baggage on board, weighing about 2700kg.
How? I cruised at about 95km/h even in the 110k zones. Acceleration was gentle, letting the diesel's torque bring the speed up rather than the horsepower (that means, a max of 2500 rpm when accelerating).
So the DPF may cause some detriment, but I'm not seeing any need to complain in my car just yet. I used to think the DPF had to go, but I did learn that my driving style GREATLY affects the economy, and even a small variation can have visible results.
Tappet
Member
That's bang on! The bigest single effect on fuel consumption is the person behind the wheel.
K
KraftyPg
Guest
16's for a petrol is about on par with other petrol drivers on this forum too from memory.
ozsnow
Member
Best I ever saw and again from the scan gauge was from Sutton Forest to Sydney (Burwood) on the freeway. Got into a mates place with the gauge reading in the low 7's. Have to say with the 06 Navara if you took it easy it would give great consumption, but if you started to push it at all it would chew.
Driving style made all the difference
That seems a little heavy. I get up to those figures when I'm driving a lot harder than normal but even with traffic it's rare to top 14s.
I'm curious - how are you working out the economy figures and what size tyres do you have?
I'm curious - how are you working out the economy figures and what size tyres do you have?
67l to fill up and 422km on clock. i fill at same servo (caltex vortex premium) all the time and try to fill to same point in filler neck (just below breather return).
Tyres-255/70/16 Bridgestone Dueller A/T.
I have just spent the better half of 4 hours reading thru most of the 60 pages of the fuel economy thread and have just tried the ECU reset that you mentioned a while back so i will see if anything changes in the next couple of weeks before i try changing my driving style.
Tyres-255/70/16 Bridgestone Dueller A/T.
I have just spent the better half of 4 hours reading thru most of the 60 pages of the fuel economy thread and have just tried the ECU reset that you mentioned a while back so i will see if anything changes in the next couple of weeks before i try changing my driving style.
