Fuel economy - what do you think?

[Aaron31]

Hi all,

I've got the 2009 D40 VSK 2.5L - about 210,000Ks on it now.
It doesnt do much - in fact after about 4 months, I have managed to use a full tank of juice without any off roading. Mostly highway - out to Healesville and back a bunch of times, with a bit of around town.
I managed to get 480Ks from the tank - thats from 'brimmed', to the fuel light on, and the needle bang on the bottom most mark. I do intend to fill it again to get a proper measurement - but not with fuel prices where they are at the moment!

Is that normal or where you would expect it to be? I am guessing not. My calcs tell me thats almost 17L per 100kms (based on 80L tank) - when its supposed to be somewhere between 12-14L per 100km.

Any thoughts as to why this might be the case?

Its had:
New fuel filter(s)
New SCV (3 or 4 years ago now)
EGR block.
Routinely changed air filter.
Routinely changed oil and filter.
I have never seen it blow any smoke.

Thanks!

 

[YD25Frontier]

That's not bad! does yours have a DPF?

 

[YowieMountain]

It is an auto I am guessing (?), as it seems excessive to me..... I have a manual yd25 (2010 Spain), I carry about 2-300kgs in tools and oil/fuel cans as standard (often more once you throw in 100kg or so of excavator parts and/or steel supplies) and also have solar panel on 2 roof racks on cab, plus another 2 racks atop homemade tub rails and a full length annexe up there - in other words, extra load mass and high wind drag.
I live in a rural, but hilly/mountainous area that has everything generally posted as 80km/hr or less so am travelling 70-90 as average speed most days and burn a tank up in somewhere between 550 and 650 kms.
I change oil and filter twice annually and do use f-10 on at least every second fill and clean my air filter weekly, due to often being in dusty conditions (people never break their earthmoving equipment in the shed ).
I find being religious about a fuel module reset(the pedal dance, as some call it) and maf sensor clean anytime you change/clean/look at air filter or have any fuel pressure issue really helps.
Between my services, the fuel flow does seem incrementally greater towards new filters time. So barely noticeable that you barely do! However the new found lung filling properties of a new air filter can make the ecu send more fuel to match, until next filter service when this "enbiggening" (true word, honest!) effect continues.
Resetting the base values each time keeps things in check, I hope - could just be my own personal placebo effect

 

[Rhino1174]

I have a 2010 Thai built auto and it runs at 18l /100k no matter what I do to it yet with old engine it ran at under 10s so I think it’s just the luck of the draw with the engine to be honest I have tried everything known to man to get better fuel economy out of this new engine and nothing makes a difference every darn sensor valve part that can be changed has been nothing hanging off it ran at 18s put a bull bar lifted it 2inches still runs at 18s don’t matter if I flog the living daylight out of it or drive like a snail still uses same fitted snorkel and 3 inch exhaust didn’t change an ounce it’s just hungry

 

[Old.Tony]

By my calcs yours is using about 14.6LPHK (70 litres divided by 4.8 = 14.5833). That's a little higher than expected - mine, loaded to about 2.7T and just having passed 390,000km is getting around 12.5s on a country run where I'm not trying to conserve fuel (I can easily get it to 11s if I try).

Idle time matters. If you leave yours idling for any length of time you'll affect the figures - mine uses around 2 litres per hour just to sit idling.

If yours is an auto, you might be seeing some extra RPM lost to the torque converter if it's getting on a bit. A change of transmission oil might help there. Driving (unladen) below 70km/h may make an auto consume more fuel because the torque converter won't lock until after that (in mine, the "magic number" is 68km/h by the GPS), even though there's less effort needed to keep the brick going (wind resistance is a killer).

 

[Aaron31]

Thanks for the replies chaps.
I have often pondered if the auto has a bit too much slip in it. On a long uphill road, it will gradually loose speed without dropping RPM. However, in 4x4 doing the tracks, it feels fine - but the torque multiplication may hide some slip (if indeed it is) but I would still expect to feel some slip if it was - particularly on a rock step or something? For the record, I have done a couple of spill and fill auto fluid changes only.

On the fuel economy thing, I was some somewhat surprised on a recent trip to Licola. I had a full tank on departure (i.e. to the 'click') then filled up again at Heyfield (90% of the way there). I calculated 12L/100 which is far more in line with what one might expect. The only things I have done is replace the fuel pressure reg and dropped in the new MAF sensor.

Back to the auto thing, has anyone had any encounters with wholesale autos in melbourne? They are supposed to be pretty helpful. I have been pondering letting them have a drive to tell me whats going on.

 

[Aaron31]

Also, what is peoples experience with a FULL tank of dinosaur juice?
On mine, filled to the 'click' it will show above full - not unusual (I dont think?).
BUT I can then do a solid ~100-120kms (highway) before it drops to the 'Full' mark.
Is that consistent with what other see?

Given that, the rate it seems to drop from there is what (pardon the pun) fuels that sense of uncertainty about fuel consumption - if that makes sense.
i.e. if I can get ~150km before it gets to 'F' I should be able to get (say) 450km before its at the half way point!!
Or the gauge isnt quite calibrated? i.e. maybe 'E' isnt actually empty? I dunno....

 

[Aaron31]

That's not bad! does yours have a DPF?

Yep.

 

[Aaron31]

It is an auto I am guessing (?), as it seems excessive to me..... I have a manual yd25 (2010 Spain), I carry about 2-300kgs in tools and oil/fuel cans as standard (often more once you throw in 100kg or so of excavator parts and/or steel supplies) and also have solar panel on 2 roof racks on cab, plus another 2 racks atop homemade tub rails and a full length annexe up there - in other words, extra load mass and high wind drag.
I live in a rural, but hilly/mountainous area that has everything generally posted as 80km/hr or less so am travelling 70-90 as average speed most days and burn a tank up in somewhere between 550 and 650 kms.
I change oil and filter twice annually and do use f-10 on at least every second fill and clean my air filter weekly, due to often being in dusty conditions (people never break their earthmoving equipment in the shed ).
I find being religious about a fuel module reset(the pedal dance, as some call it) and maf sensor clean anytime you change/clean/look at air filter or have any fuel pressure issue really helps.
Between my services, the fuel flow does seem incrementally greater towards new filters time. So barely noticeable that you barely do! However the new found lung filling properties of a new air filter can make the ecu send more fuel to match, until next filter service when this "enbiggening" (true word, honest!) effect continues.
Resetting the base values each time keeps things in check, I hope - could just be my own personal placebo effect

Auto yep. I generally do the 'pedal dance' when I mess with anything in that department - but it has never yielded anything noticeable to me. If I was getting 550-650 per tank, rest assured these posts would not exist! Those numbers are far more reasonable to me. My brother has an 07 Triton (MN?) manual - and gets those numbers without trying. In terms of what I 'lug' around, I do have drawers in the back, fridge, chain-a-saw-rus, swags, chairs. I have an awning on a tradie rack - with a couple of recovery 'planks' (never used!) strapped to the rack as well. But I dont think its much in the overall scheme of things - 350kg max.

The only thing that crossed my mind in thinking about all this is the Aliexpress MAF sensor replacement which I did recently. I had cleaned the old one on more than one occasion - again, never really noticing any material change. Maybe that new sensor has yielded something? A trip is planned for this weekend to the Murray - I will collect more numbers. Im not fussed about the around town number. I am more interested in getting the highway number down - as the better overall indicator.

As another indicator and during the same Licola trip i mentioned above, I filled up at Dargo ($2.50/L!!!) and went north on the high plains road to hotham (via devils hollow and a couple of other minor side runs), then out via snow road, hume hwy, euroa, merton, yea - back track from yea (floods) to alex, spur, healesville, ringwood. Of course, I didnt think to reset the odo, but according to google and considering those side runs a solid 500 kms. The light was on when i got home.

So maybe im not that far off the mark. Now i am starting to thing the new MAF has helped....

 

[Rhino1174]

My fuel gauge goes way over f mark takes exactly 50km. For it to come down to f mark then the first 100km it is slow to move needle then over the 150km it drops straight to half a tank everytime I can’t get anymore than 350km out of a tank if I try still I’m about to get another torque converter I’ve been told that could be the issue I’m losing all my power before I get drive this bad fuel consumption so I’m searching for a converter that won’t need a second mortgage anyone ???

 

[Aaron31]

OK - so the trip to Echuca and back (to Melbourne) and then a few other excursions:

From filled up (i.e. to the click on the pump) where the gauge indicates above full - to the full mark: 120KM.
To the 3/4 full mark: 230Km
To the 1/2 full mark: 340Km
To the 1/4 full mark: I missed it......
To the E mark, light on, beep on start: 625KM
Fill up (back to the click) 75.1L - this equates to 12.1L per 100KM.

I have NEVER had 620Ks to a tank before. I would struggle to get 460 (average) to maybe 490 if there was a lot of tail wind! I had to think hard as to if I had done a 'splash and dash' somewhere - but no. Its now apparent that the trip up/over licola/dargo etc would have delivered a similar result - if it wasnt punctuated by a bunch of 4LO work etc.

I have to say - am quite pleased with this - but then there is the question of why???

A couple of months ago I changed the fuel pressure relief valve (on the back of the fuel rail). This was to try and address a random stall issue at startup - but I have since established that it isn't the cause (my assessment is now that a loose negative battery terminal and a lot of moisture is/was the more likely culprit). Could it have made any difference to fuel economy? Not likely in my book.

I also went from 5W-40 Penrite Enviro+ to 10W-40 Penrite Enviro+ at the last change in December. Only did this because I accidently got the wrong one. I was ready to go swap it but then I thought...she's up to ~215,000kms now - a tad extra thickness at start is not going to do it any bother. Again, I dont think its a factor - maybe a very minor one at best.

To me, the most likely 'improver' was the new MAF sensor. I replaced it on a whim only - with a part from Aliexpress (along with that relief valve). For the $30 it cost, I figured "why not" - very aware of the potential for other issues resulting from a potential dodgy part. However, as I think I have indicated elsewhere here, the differences in its physical appearance (at least) is not apparent.

What's the wash up? If you have above average fuel consumption, try a new MAF (and do the pump reset). If it works, it will pay for itself in a couple of tanks!!! I would be very interested to see other peoples results from the fuel gauge level vs KMs travelled. It would appear that distance travelled at half a tank is a decent indication of what you could get - if you ran it dry.

Enjoy.

 

[Rhino1174]

OK - so the trip to Echuca and back (to Melbourne) and then a few other excursions:

From filled up (i.e. to the click on the pump) where the gauge indicates above full - to the full mark: 120KM.
To the 3/4 full mark: 230Km
To the 1/2 full mark: 340Km
To the 1/4 full mark: I missed it......
To the E mark, light on, beep on start: 625KM
Fill up (back to the click) 75.1L - this equates to 12.1L per 100KM.

I have NEVER had 620Ks to a tank before. I would struggle to get 460 (average) to maybe 490 if there was a lot of tail wind! I had to think hard as to if I had done a 'splash and dash' somewhere - but no. Its now apparent that the trip up/over licola/dargo etc would have delivered a similar result - if it wasnt punctuated by a bunch of 4LO work etc.

I have to say - am quite pleased with this - but then there is the question of why???

A couple of months ago I changed the fuel pressure relief valve (on the back of the fuel rail). This was to try and address a random stall issue at startup - but I have since established that it isn't the cause (my assessment is now that a loose negative battery terminal and a lot of moisture is/was the more likely culprit). Could it have made any difference to fuel economy? Not likely in my book.

I also went from 5W-40 Penrite Enviro+ to 10W-40 Penrite Enviro+ at the last change in December. Only did this because I accidently got the wrong one. I was ready to go swap it but then I thought...she's up to ~215,000kms now - a tad extra thickness at start is not going to do it any bother. Again, I dont think its a factor - maybe a very minor one at best.

To me, the most likely 'improver' was the new MAF sensor. I replaced it on a whim only - with a part from Aliexpress (along with that relief valve). For the $30 it cost, I figured "why not" - very aware of the potential for other issues resulting from a potential dodgy part. However, as I think I have indicated elsewhere here, the differences in its physical appearance (at least) is not apparent.

What's the wash up? If you have above average fuel consumption, try a new MAF (and do the pump reset). If it works, it will pay for itself in a couple of tanks!!! I would be very interested to see other peoples results from the fuel gauge level vs KMs travelled. It would appear that distance travelled at half a tank is a decent indication of what you could get - if you ran it dry.

Enjoy.

Hi call me dumb if you like please elaborate on the pump reset you mentioned ?? I haven’t tried this yet I’m still struggling I keep reading about people saying they do a pedal dance also but yet to find any instructions on this procedure also I’m guessing it’s like disconnecting the battery?? Any help be worth it I have changed my sensors now and will see if makes a difference crossing my fingers again this 18l/100km is getting out of control that’s on a good day Crept upto 22l around town last week I almost died at the fuel pump cheers

 

[Aaron31]

See here: https://www.nissan-navara.net/threads/how-to-reset-ecu-and-fuel-pump-d40.3878/

 

[Rhino1174]

See here: https://www.nissan-navara.net/threads/how-to-reset-ecu-and-fuel-pump-d40.3878/

Thanks I just gave it a whirl will see if it makes any changes to the thirsty beast

 

[Chapster]

See here: https://www.nissan-navara.net/threads/how-to-reset-ecu-and-fuel-pump-d40.3878/

Two other points mentioned further down in the above thread (to save you looking for them):

1. After the reset, go ahead and start the car. Don't turn the ignition off again before starting the car and taking it for a run.
2. Do the reset when the engine is already warm and running at usual operating temperature.

To those more knowledgeable, please jump in and correct me if that is not right.

Cheers for the tip on the cheap MAF @Aaron31. I've wanted to try this for sometime to see if it would improve my own economy but could not justify the outlay on a hunch. Very happy to roll the dice though for only $30 or so.