06 67k Miles poor gas milage

[oldAGE]

Originally Posted by 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

Yup... was going to point you to that... Once I saw "remove intake manifold..." that was the end of that. I have all the tools and talent in the world but due to some reduced physical ability... the towel - she is thrown.

AGE

[Carguy75]

Originally Posted by oldAGE

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

You are too high strung about this. If you do not want to change your spark plugs, do not change the spark plugs. If you ask any mechanic or use logic, a new spark plug will generate a better spark than one with over 60K miles of wear on it. You say that you are old, so stop stressing yourself over the small details, not good for the heart. If you want to conduct an experiment comparing MPG's of old spark plugs vs. new spark plugs against how many MPG's you gain or lose, so be it. I used to get an average of 18-19 MPG with the old plugs, and now I get 21-22 MPG after the change. I have no written record of my mileage from day to day. So, take the information as is or not. Your choice. By the way, the Murano do not have a clutch that will slip and if your CVT have a slipping belt, MPG's would not be an primary concern anymore, but I see your point. Now see mine.

[oldAGE]

Originally Posted by Carguy75

You are too high strung about this. If you do not want to change your spark plugs, do not change the spark plugs. If you ask any mechanic or use logic, a new spark plug will generate a better spark than one with over 60K miles of wear on it. You say that you are old, so stop stressing yourself over the small details, not good for the heart. If you want to conduct an experiment comparing MPG's of old spark plugs vs. new spark plugs against how many MPG's you gain or lose, so be it. I used to get an average of 18-19 MPG with the old plugs, and now I get 21-22 MPG after the change. I have no written record of my mileage from day to day. So, take the information as is or not. Your choice. By the way, the Murano do not have a clutch that will slip and if your CVT have a slipping belt, MPG's would not be an primary concern anymore, but I see your point. Now see mine.

Your point is well taken. I see your point. I understand exactly what you are saying and I understand exactly where you are coming from. I stress over absolutely nothing. But throwing good money after bad for possibly incidental change is not wise. As I have written, I feel more transmission transitions than in the past. I also believe she is more throaty than usual.

So, I am an educated scientist who has been an IT professional for almost 30 years. The things I do in my day to day life are based on a well defined thought process. Yeah, it's scientific method. Cause and affect. Then as a Project Manager, I take the financial concerns into account too.

My rationale is not stress, it's trying to find root cause to remedy the problem that might be more costly to "fix" if it has little bearing on the health of the vehicle and it's intended use. Yes, I agree that changing the plugs should mean better mileage. If I could spend $30 on DIY, then I would just do it because "it can't hurt." For $30, it can't hurt. For the documented $250 within these threads, that's another story. And since I am statistically rich (I am a 9%'er), it does not mean I am foolish with how I want to spend my hard earned time and money.

I did not expect to change a wheel bearing at 65K but I had too. I did not expect to change the serpentine belt at 70K but I had too. I have a pile of brake components in my garage that I will install when the temps are in the 70s because it will be about time and around 80K. All rational and for a reason.

I will post back here what I figure out is the reason for my crappy gas mileage once I figure it out. And CarGuy might be the guy with the right answer for the right reason. I will also post my cost for others to compare.

Thanks for the feedback and information.
AGE

[jinhao]

oldAGE: your posts are extremely tiring to read. It's like you're trying to write verbatim your thoughts in your post instead of being concise and to the point.

Anyways, I noticed a drop in MPG in the murano recently. I have a 06 Murano currently at 102k miles. We did a road trip to Wisconsin 2 summers ago and was able to get 24mpg average. Recently I was only able to get 20.2 on a round trip road trip to PA. Thinking it was my plugs, I replaced them with the OEM NGK R plugs. When I removed the plugs, they were visibly gapped wrong at this point due to being completely worth down. While I was at it, I replaced the air filter and PCV valve. So new plugs, filter and PCV valve.. I did essentially the same trip again. MPG: 20.4mpg.

There should be no reason I am getting ~20mpg on a 95% hwy trip. I am actually trying to get the best gas mileage I can too while driving. Coasting, avoiding gear ratio changes.... etc.

Whats next? I have no CEL but I've searched and found that the knock sensor or AFR sensors could be bad but still not throw a code....

PS-change your plugs when you're supposed to. It is a maintenance item and does not last forever. The point is not better gas mileage but to keep your car operating at its best. Advance Auto has the OEM plugs for $40 (for 6) and the intake manifold gasket for $20

[nitely]

I'd blame it to the winter blend.

[oldAGE]

Originally Posted by jinhao

oldAGE: your posts are extremely tiring to read. It's like you're trying to write verbatim your thoughts in your post instead of being concise and to the point.

Anyways, I noticed a drop in MPG in the murano recently. I have a 06 Murano currently at 102k miles. We did a road trip to Wisconsin 2 summers ago and was able to get 24mpg average. Recently I was only able to get 20.2 on a round trip road trip to PA. Thinking it was my plugs, I replaced them with the OEM NGK R plugs. When I removed the plugs, they were visibly gapped wrong at this point due to being completely worth down. While I was at it, I replaced the air filter and PCV valve. So new plugs, filter and PCV valve.. I did essentially the same trip again. MPG: 20.4mpg.

There should be no reason I am getting ~20mpg on a 95% hwy trip. I am actually trying to get the best gas mileage I can too while driving. Coasting, avoiding gear ratio changes.... etc.

Whats next? I have no CEL but I've searched and found that the knock sensor or AFR sensors could be bad but still not throw a code....

PS-change your plugs when you're supposed to. It is a maintenance item and does not last forever. The point is not better gas mileage but to keep your car operating at its best. Advance Auto has the OEM plugs for $40 (for 6) and the intake manifold gasket for $20

Thanks for the writing critique... and you prove my point. You changed your plugs with the expectation of better mileage but that was not the result. So that proves CarGuy's logic is not exact science either. It's hit or miss unless better diagnostics are performed.

Here's concise - my car has no other operational issues other than what seems like it's more throaty (exhaust leak at manifold or cat?), has an odd low speed downshift feel (not a thunk but rather what seems like a hard shift), and gets crappy mileage not related to winter weather because I have been driving it in winter for six winters or more with much colder temps and much better avg mileage. Other than that, it started with out issue in 10 below last week, once warm, ran just fine. Turns off fine, idles fine... Yes, plugs at the standard mileage maintenance will be definite if not before. And, no, I can't change my own plugs for $60 because of the work necessary due to the manifold gasket work so I will be needing to pay someone to do the work.

So, lots of writing to support my position - which most people choose to ignore like the logic of cost to get better mileage actually might cost more money than the extra expense of gasoline. But I digress from concise....

AGE

[fbdyws6]

Hello all,

I see this post has gotten slightly off topic, however the discussion enlightening to say the least. I have dropped my murano off at the dealer this morning and I will report back their findings about the CVT issue when I get it back. Thanks all.

[oldAGE]

Originally Posted by fbdyws6

Hello all,

I see this post has gotten slightly off topic, however the discussion enlightening to say the least. I have dropped my murano off at the dealer this morning and I will report back their findings about the CVT issue when I get it back. Thanks all.

I wouldn't say off topic at all actually. I am very interested in what you find and also understand what costs, if any, are associated with the findings. Why? Because original owners were afforded an extension of the original transmission warranty due to early production problems of the CVT. So let us know your findings and any costs associated with diagnostics and repair. Then, of course, we would want to see if your mileage has improved because of any work performed.
Thanks for keeping this going.
AGE

[Halwg]

This post has been very entertaining. Maybe someone will actually find out what is causing lower mileage. I also attribute it to winter gasoline, cold weather, more idle time, bad roads, etc. I have a 2010 Ford Explorer with 46,000 miles, and a 2012 MO with 9,000 miles and I can tell you both of them get 2 - 3 mpg lower in the winter than in the summer. The MO is averaging 21 mpg on highway trips, and the Explorer 18 mpg on highway trips. That's about 3 mpg less for both.

And I can tell you neither vehicle needs new plugs. It's really something you just have to live with when you live in areas that have extreme temperature fluctuations.

[fbdyws6]

Just heard from the dealer regarding transmission issue "Transmission shows no codes, no faults, and is shifting properly" sigh, I had a feeling that would be the case. However they are replacing my bad window motor and regulator under warranty so the trip wasn't a total loss... So it seems I'll have to wait until it gets worse, or something fails I guess...

[oldAGE]

Originally Posted by fbdyws6

Just heard from the dealer regarding transmission issue "Transmission shows no codes, no faults, and is shifting properly" sigh, I had a feeling that would be the case. However they are replacing my bad window motor and regulator under warranty so the trip wasn't a total loss... So it seems I'll have to wait until it gets worse, or something fails I guess...

Darned... not that we want you to have a CVT problem but I am sure that there are a few of us here who seem to have the same "symptom." Are you the original owner? Did they ding you any $$$ for the diagnostic efforts?

AGE

[fbdyws6]

Originally Posted by oldAGE

Darned... not that we want you to have a CVT problem but I am sure that there are a few of us here who seem to have the same "symptom." Are you the original owner? Did they ding you any $$$ for the diagnostic efforts?

AGE

Second owner, bought it in 2010 with 18,9xx miles on it. it seemed well maintained. I have a "pre-owned security plus" extended warranty on it until 78,9xx miles so I was not charged any diagnostic fees, only a $50 deductible but like I said they changed out my window motor and regulator while I was there. I've just been wondering how much diagnostic work was really done...

[oldAGE]

Originally Posted by fbdyws6

Second owner, bought it in 2010 with 18,9xx miles on it. it seemed well maintained. I have a "pre-owned security plus" extended warranty on it until 78,9xx miles so I was not charged any diagnostic fees, only a $50 deductible but like I said they changed out my window motor and regulator while I was there. I've just been wondering how much diagnostic work was really done...

I hear you. I need some time to be able to drive into my dealer and do the same and see what they have to say. Of course, I will report back here. Glad your window is fixed... you won't be needing it though. Our ugly weather should soon be upon you for the next few days. Brrrrr... Still 4 below at 10:40 in the morning here in Madison.
AGE

[Carguy75]

Originally Posted by jinhao

oldAGE: your posts are extremely tiring to read. It's like you're trying to write verbatim your thoughts in your post instead of being concise and to the point.

Anyways, I noticed a drop in MPG in the murano recently. I have a 06 Murano currently at 102k miles. We did a road trip to Wisconsin 2 summers ago and was able to get 24mpg average. Recently I was only able to get 20.2 on a round trip road trip to PA. Thinking it was my plugs, I replaced them with the OEM NGK R plugs. When I removed the plugs, they were visibly gapped wrong at this point due to being completely worth down. While I was at it, I replaced the air filter and PCV valve. So new plugs, filter and PCV valve.. I did essentially the same trip again. MPG: 20.4mpg.

There should be no reason I am getting ~20mpg on a 95% hwy trip. I am actually trying to get the best gas mileage I can too while driving. Coasting, avoiding gear ratio changes.... etc.

Whats next? I have no CEL but I've searched and found that the knock sensor or AFR sensors could be bad but still not throw a code....

PS-change your plugs when you're supposed to. It is a maintenance item and does not last forever. The point is not better gas mileage but to keep your car operating at its best. Advance Auto has the OEM plugs for $40 (for 6) and the intake manifold gasket for $20

Did you reset your MPG trip meter after installing the new parts? Also, check your tire pressure. In the winter the tires tend to lose several PSI due to the change in air temperature, which could also affect MPG.

[Carguy75]

Originally Posted by oldAGE

Thanks for the writing critique... and you prove my point. You changed your plugs with the expectation of better mileage but that was not the result. So that proves CarGuy's logic is not exact science either. It's hit or miss unless better diagnostics are performed.

Here's concise - my car has no other operational issues other than what seems like it's more throaty (exhaust leak at manifold or cat?), has an odd low speed downshift feel (not a thunk but rather what seems like a hard shift), and gets crappy mileage not related to winter weather because I have been driving it in winter for six winters or more with much colder temps and much better avg mileage. Other than that, it started with out issue in 10 below last week, once warm, ran just fine. Turns off fine, idles fine... Yes, plugs at the standard mileage maintenance will be definite if not before. And, no, I can't change my own plugs for $60 because of the work necessary due to the manifold gasket work so I will be needing to pay someone to do the work.

So, lots of writing to support my position - which most people choose to ignore like the logic of cost to get better mileage actually might cost more money than the extra expense of gasoline. But I digress from concise....

AGE

I would wait until summer and then check your MPG again. If you are having temps. in the sub-freezing range of 10 below in your area, then it may be the cold air that is reducing your MPG. I would check your tire pressure as well,because tires may lose some air pressure in the winter and ruin your MPG due to increase rolling resistance. Again not exact science, but basic trouble shooting and common knowledge. Rarely any solution is an exact science or 100%, even science experiments has variables that are random. Only when enough samples concludes with the same outcome does it become proven. Hell, even NASA has to trouble shoot problems during missions with solutions that may or may not work until a working solution is found. Trial and error. So I were you, I would read all the solutions to low MPG given on this forum and then pick the solutions that may work by starting with the simple causes of low MPG first and hopefully you will find your solution.