# poor fuel consumption



## fm9111 (Sep 8, 2016)

*hi

I have a Nissan Pathfinder 2008, with 300k KM.

I have been experiencing an issue with fuel consumption, 95. A full tank only allows 290 to 330 km intercity. Average fuel economy is 19.5 per 100.

The issue started after i had a full transmission gear change as the old one stopped working. I've already have the gear checked by a technician, and an overall check to no results. I have also had the air throttle, the fridge,the oxygen sensor ,and the mass air flow sensor cleaned .​*


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## quadraria10 (Jul 6, 2010)

What kind of gas mileage should you be getting? What was it before the transmission repair? Quick check at Fuelly.com shows people getting fairly similar 18+ L per 100 kms in city driving. Are you using high ethanol blend gasoline? When did you last replace your spark plugs? And did you replace the o2 sensors given your high mileage?


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## fm9111 (Sep 8, 2016)

Fuel filter changed (used) and Spark plugs new changed at 250k km
Using high ethanol blend gasoline right now
i did not replace the o2 sensors
There are 4 O2 sensors which one I need to change ?


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## kukla (Apr 1, 2010)

fm9111 said:


> *hi
> 
> I have a Nissan Pathfinder 2008, with 300k KM.
> 
> I have been experiencing an issue with fuel consumption, 95. A full tank only allows 290 to 330 km intercity. Average fuel economy is 19.5 per 100.​*


*

what does the "95" designate?
19.5 what per 100 what?
Are you calculating your fuel economy or going by the "mpg" dashboard computer readout?



fm9111 said:



The issue started after i had a full transmission gear change as the old one stopped working. I've already have the gear checked by a technician, and an overall check to no results. I have also had the air throttle, the fridge,the oxygen sensor ,and the mass air flow sensor cleaned .​

Click to expand...



what does "fridge" refer to?



fm9111 said:



Fuel filter changed (used) and Spark plugs new changed at 250k km
Using high ethanol blend gasoline right now
i did not replace the o2 sensors
There are 4 O2 sensors which one I need to change? 

Click to expand...

I don't think there is any replacement interval for O2 sensors, they just get replaced when they fail (if they fail).​*


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## quadraria10 (Jul 6, 2010)

The 19.5 per 100 is Litres per 100 Kilometers, basically he is getting roughly 12 mpg (US) in all city driving. The 95 is the gas he is using, which I think is Aussie premium unleaded
With regard to o2 sensors, they can go a long time before reading bad and setting of a CEL, but they do get old and slow and degrade over time, and NGK suggests they should be replaced at some point around 150,000 kms. 
With regard to FM9111's Pathfinder, he said its at 300,000 kms and his sensors would be 8 years old. I doubt they are operating like new. That said, its pricey to have to change 4, and if no code has popped up yet, you might want to try switching to gasoline with less ethanol. Then you could compare your mileage. Ethanol has less energy than gasoline and you get worse gas mileage as a result. Winter formulations of gas tend to increase mpg as well. Try driving a little more conservatively as well, and then compare it to the 15 mpg (US) or so that its rated for.
https://www.fueleconomy.gov/feg/bymodel/2008_Nissan_Pathfinder.shtml

I also wonder if it might be related to the transmission rebuild. Maybe there was some reprogramming required? Good luck with it.


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## kukla (Apr 1, 2010)

12 mpg is low, but not unheard of, so maybe not "abnormal"
in bad city traffic with the A/C running, I've seen it
too bad we don't have more info, such as 2WD or 4WD, average highway MPG (I've gotten as good as 24 MPG at times on the highway).

"A full tank only allows 290 to 330 km intercity."
what does this actually mean?
does it mean that he ran out of fuel at 290-330, or is it a "guesstimate" based upon the dashboard calculator? 

a little (actually, a lot) more accurate info would be helpful

I've gotta go clean my "fridge" now............


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## quadraria10 (Jul 6, 2010)

"A full tank only allows 290 to 330 km intercity."
what does this actually mean?

To me that reads he gets 290 to 330 km per tank of city driving, based on full to the low fuel light coming on.


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## kukla (Apr 1, 2010)

quadraria10 said:


> "A full tank only allows 290 to 330 km intercity."
> what does this actually mean?
> 
> To me that reads he gets 290 to 330 km per tank of city driving, *based on full to the low fuel light coming on. *


.......that's what I sort of wondered
but that's a poor indicator of actual distance left, as is the "miles to empty" feature guideline..........is only a guideline
"distance to empty" and the low fuel warning light are notoriously skewed toward an inaccurately low fuel level indication
we all should know by now that the only accurate consumption figure is derived as a comparison between actual distance travelled divided by the actual quantity of fuel consumed
..........anything else is just a waste of bandwidth & time.......... 
if the OP gets 12-13 mpg in city and 20-22 hwy, there's probably nothing wrong, other than maybe a "heavy" right foot at times, which through owning two R51s, we have learned is the singlemost important factor in poor fuel economy

now, about that "fridge"................


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## rogoman (Dec 16, 2004)

kukla said:


> "distance to empty" and the low fuel warning light are notoriously skewed toward an inaccurately low fuel level indication
> we all should know by now that the only accurate consumption figure is derived as a comparison between actual distance travelled divided by the actual quantity of fuel consumed
> ..........anything else is just a waste of bandwidth & time..........
> if the OP gets 12-13 mpg in city and 20-22 hwy, there's probably nothing wrong, other than maybe a "heavy" right foot at times, which through owning two R51s, we have learned is the singlemost important factor in poor fuel economy
> ...


Agree'd on the only accurate MPG measurement method.

WOW, I didn't know a fridge was a Nissan option. Wish I had one; this way I could keep my soda nice and cool.


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## kukla (Apr 1, 2010)

rogoman said:


> Agree'd on the only accurate MPG measurement method.
> 
> WOW, I didn't know a* fridge *was a Nissan option. Wish I had one; this way I could keep my soda nice and cool.


yeah, huh?


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## NeedyNismo (Oct 7, 2016)

12MPG?! Seriously?! Oh man yeah you gotta get that checked out...


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## kukla (Apr 1, 2010)

NeedyNismo said:


> 12MPG?! Seriously?! Oh man yeah you gotta get that checked out...


what year Pathfinder do you have?


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## kukla (Apr 1, 2010)

don't we just love these "hit & run" posts?
it's so nice to try to help people out, and they won't even give you the time of day.


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## smj999smj (Jan 1, 2006)

Rear oxygen sensors have nothing to do with engine management; they are there so the ECM can monitor the catalytic converter efficiency and nothing else. My 2006 Pathfinder LE AWD averages 17.5 MPG. On the interstate, it can see 21 MPG and in the city, it can drop to around 15-16 MPG, using 93 Octane premium in the US. I use the cruise control whenever possible for best mileage and a light foot on the gas pedal helps a lot. 
One of the things I think is key here is the "high ethanol blend gasoline" being used. That, alone, can drop gas mileage 2-3 MPG. I'm thinking that there is nothing wrong with his Pathfinder.


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## fm9111 (Sep 8, 2016)

sorry for my bad english
now i using 95 Octane premium A full tank only allows 290 to 330 km intercity 
before i used 91 Octane premium A full tank only allows 210 to 260 km intercity
all based upon the dashboard calculator
my Pathfinder is 4WD, Average fuel economy is 19.5 per 100 on screen on the middle 
i think should be 15 to 17 max 
i already checked by computer for all engine and transmission gear 
no code has popped up
what about the mass air flow sensors is it need to replace​


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## quadraria10 (Jul 6, 2010)

I guess we are trying to tell you that while your gas mileage is not great, it may still be normal. You can try cleaning your MAF but it may not make any difference. I would do the upstream o2 sensors before that. They are due for a change anyway. Good luck.


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