06 67k Miles poor gas milage

[fbdyws6]

Hello all,

So I have a 2006 murano S AWD. Within recent months I've noticed my gas mileage (as reported by the console screen) has dropped from 21-22mpg to a steady 19.5mpg (when I say steady I mean I can not get above this) Only thing I'm thinking could be related is I am getting symptoms I've read about on here being related to CVT issues. What can be described as a hard downshift at low speeds, also what feels like a jerky bounce when letting off the gas in traffic. I'm going to try to drop it off at the dealer this week, but I'm just looking for other opinions in the mean time. Thanks guys.

[starfighter330]

Originally Posted by fbdyws6

Hello all,

So I have a 2006 murano S AWD. Within recent months I've noticed my gas mileage (as reported by the console screen) has dropped from 21-22mpg to a steady 19.5mpg (when I say steady I mean I can not get above this) Only thing I'm thinking could be related is I am getting symptoms I've read about on here being related to CVT issues. What can be described as a hard downshift at low speeds, also what feels like a jerky bounce when letting off the gas in traffic. I'm going to try to drop it off at the dealer this week, but I'm just looking for other opinions in the mean time. Thanks guys.

I've been having the same issue on my '05 Murano SL AWD. I have a little over 89,000 miles on it right now. It's been 2 years (around 60K miles) since I have seen 22 mpg average (in/out combined). I currently get around 18.5 mpg average (combined) now. However, about the other issue, over the last 2 months, I have noticed the hard downshift at lower speeds and jerky bounce when letting off the gas in traffic. Good to hear I am not alone on this issue but I called the dealership to look into it since the CVT transmission is still under warranty.

[Carguy75]

I would check your tire pressure first. Next I would pull the plugs from the front cylinder bank and check the plugs to see if it is worn. I suspect you may need a spark plug change. Also check your air filter, a dirty air filter can cause MPG's to go down as well affect engine performance.

[RkyMtnHi]

I am seeing lower gas mileage on my 06 SE, and I attribute that to cold mornings here in Denver, and short trips. If I do a little highway driving, it goes up to normal.

[Pilgrim]

At 67K you don't need plugs - that's a 100K service.

It may just be weather if you've had sustained cold temps.

Also worth checking filters and tire pressures. I frankly wouldn't worry about it much until the weather warms up. Your variance is well within that caused by cold weather.

[hali2776]

replaced the air filter on my 06 and the fuel economy improved. but the majority of my family's driving is city ( 15-16 liters per 100km ) but on a recent trip from Halifax to Quebec city (about 1000km) we got much better ( low 12's per 100km) and that was at a speed of around 75mph. I have 88K miles on mine.

[Carguy75]

Originally Posted by Pilgrim

At 67K you don't need plugs - that's a 100K service.

It may just be weather if you've had sustained cold temps.

Also worth checking filters and tire pressures. I frankly wouldn't worry about it much until the weather warms up. Your variance is well within that caused by cold weather.

I disagree about the spark plugs. I changed my spark plugs at about 89K and notice the electrodes was worn down a lot. i even had one plug with a crack insulator. Because the older plugs fire, do not mean that they are producing a strong spark like when they were new due to the increase gap cause by the worn electrodes. I believe in changing spark plugs every 60K, however due to the work involved with changing the Murano spark plugs I would go longer if possible until gas mileage suffer or the Murano misfire.

[oldAGE]

Yup... add me to the list... '06 with 73K. Tires good, filters good, new serpentine belt good... harsh downshift at times. Mileage in the toilet. Yes, the weather is cold but I have a commute that is 96% highway and have years of 21 mpg in cold weather and 24 mpg average. Now in the 20 or lower range. Something is amiss.

I would be interested to hear from those who have pulled the plugs...

AGE

[Carguy75]

Originally Posted by oldAGE

Yup... add me to the list... '06 with 73K. Tires good, filters good, new serpentine belt good... harsh downshift at times. Mileage in the toilet. Yes, the weather is cold but I have a commute that is 96% highway and have years of 21 mpg in cold weather and 24 mpg average. Now in the 20 or lower range. Something is amiss.

I would be interested to hear from those who have pulled the plugs...

AGE

I have an '06 Murano. Pulled my plugs at 89K and the spark plug electrodes was extremely worn down. I should have pulled my plugs around 60-70K.

[oldAGE]

Originally Posted by Carguy75

I have an '06 Murano. Pulled my plugs at 89K and the spark plug electrodes was extremely worn down. I should have pulled my plugs around 60-70K.

I understand exactly what you are saying but you provide little evidence of what this remedied. Of course, I know exactly how internal combustion engines work, etc. But it's interesting to know that... "... at X miles, I noticed that my average MPG declined from around Y to Z and when I replaced my plugs, I was averaging Y again..." I regularly replace all normal wear-n-tear items myself including the clever "need to remove the glove box to replace the" cabin filter... I see the Spark Plug replacement includes replacing manifold gaskets. Can't do that any longer (physical limitation) so off I will go for some local trusted shop estimates.


AGE

[JayS]

It's probably just because it's winter. Here's an awesome write up my friend Mike who owns Innovative Tuning in Buffalo, NY did a while back about why your winter gas mileage is so much worse.

NYSpeed - New Yorks ONLY Statewide Automotive Forum - Why your fuel economy is so much worse in the winter..

[Carguy75]

Originally Posted by oldAGE

I understand exactly what you are saying but you provide little evidence of what this remedied. Of course, I know exactly how internal combustion engines work, etc. But it's interesting to know that... "... at X miles, I noticed that my average MPG declined from around Y to Z and when I replaced my plugs, I was averaging Y again..." I regularly replace all normal wear-n-tear items myself including the clever "need to remove the glove box to replace the" cabin filter... I see the Spark Plug replacement includes replacing manifold gaskets. Can't do that any longer (physical limitation) so off I will go for some local trusted shop estimates.


AGE

This is not a scientific experiment here. Fact. New spark plugs will give better MPG than old worn sparkplugs. However, will new spark plugs improve your particular situation? Who knows. However, changing the spark plugs helped my Murano obtain higher MPG's. Sorry, I do not have an powerpoint presentation with a graph depicting the curve of my MPG's before and after my spark plug change to verify my gains and losses.

[oldAGE]

Originally Posted by JayS

It's probably just because it's winter. Here's an awesome write up my friend Mike who owns Innovative Tuning in Buffalo, NY did a while back about why your winter gas mileage is so much worse.

NYSpeed - New Yorks ONLY Statewide Automotive Forum - Why your fuel economy is so much worse in the winter..

A very good read. Thanks for the link.

This is all very technically interesting and accurate at 5000 ft. (meaning the big picture, looking down from 5000 ft.). But as this is a 2006 Murano and it's now the winter of 2012/13, and I am the original owner... I have been driving this Murano across six Wisconsin winters. One of those winters included normal cold and record snows (over 120")... One of those winters included record "warmth" (Last year, we did not break 0 degrees and we had more temps in the 30s than in recorded history -- breaking 80s in March).

So, while I personally write I normally get around 21 in the Winter months, it's because I normally average around 21 during the winter months. The last three weeks, I have barely broken 19 and change and my normal average has fallen over the last 10 months considerably. I used to see topping off my tank, my range calculated in the 430s-460s (really topping it off)... Now when I see 400, I am happy. I often don't see better than 390. Of course, that crappy algorithm is not an exact science (and poorly written) but it's an indicator nonetheless.

At first I thought the problem was related to a failing front wheel hub bearing. Replaced that and saw no difference although she did handle a bit better. Weird that I could notice it but I did... foot off the accelerator at idle and she would roll.

So, yes... winter kills mileage and warm weather reformulation of gasoline might kill mileage too... but something is REALLY killing mileage and it's not old man winter to that degree.

I have my target on Plugs as that might be the lower cost "throw hardware at the problem" option. As my Nissan Extended CVT warranty is still in affect, that will be the next step.

AGE

[oldAGE]

Originally Posted by Carguy75

This is not a scientific experiment here. Fact. New spark plugs will give better MPG than old worn sparkplugs. However, will new spark plugs improve your particular situation? Who knows. However, changing the spark plugs helped my Murano obtain higher MPG's. Sorry, I do not have an powerpoint presentation with a graph depicting the curve of my MPG's before and after my spark plug change to verify my gains and losses.

No Powerpoint necessary. The point is, you never said that you changed your plugs because of poor mileage nor did you indicate that your mileage improved when you changed your plugs. Now that you stated that, it helps. And sorry to disagree but yes, this is a scientific experiment. Anything we do with engineered product is.

Fact: New Plugs might give you better MPG than old worn spark plugs but if your mileage is being affected by a slipping belt or clutch in your transmission, then you might not see any improvement with New Spark Plugs other than your favorite mechanic buying a new BluRay player thanks to your efforts.

So, more science and math - loss of four MPG = 80 less miles per 20 gallon tank. 80 miles at 21 mpg = 3.8 gal vs. 80 at 19 mpg = 4.21 gal. Difference = .41 gal greater consumption. Cost of greater consumption at $3.30 per gallon is $1.35 per tank. If a discounted cost to replace the plugs = $180, then the total number of extra gallons consumed per fill up compared to the cost to replace the plugs could equate to 133 tank fills. If I fill up every nine days or so, that's around 41 fills per year. The cost to fix this "problem," might be equivalent to over three years of gasoline usage. Of course, all these numbers do change with cost of fuel, cost of repair, and continued degradation of mileage based on some factor of potential cause.

So, throwing parts at a problem is great but having anecdotal evidence by experience is why we come to these forums. Yours is input... Pilgram's is input. Science is based on inputs and results.

So, here is another question: Might an exhaust leak potentially adversely affect MPG by a factor of two or three miles per gallon? I don't mean a roaring "MY CATALYTIC CONVERTER AND MUFFLER ARE NOW FIVE MILES BEHIND ME!!!" but hmmm... it's a bit more throaty than she used to be I think...

AGE

[JayS]

I haven't looked... but is it that bad to change the plugs on a Mo? I've had some vehicles in my past that weren't terribly fun but with a good mix of extensions and socket u-joints I've always been able to DIY the plug changes.

EDIT: Nevermind... damn you Nissan
2006 Murano spark plug change