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Discussion Starter #1
I know this has been covered in various threads.... but my gas milage on my MO is to the point where I'm considering calling a lawyer about a lemon law claim.

Sticker says 20 city, we all know this. We also all know that that number is an average or estimate of what the EPA feels the majority of these vehicles will achieve. My sticker says actual observed mileage is 17 - 23 city. Seems reasonable. I could live with that.

I do the majority of my driving in "city" conditions, with the exception of occasional trips up to visit the family at Lake Tahoe (about 100 miles round trip, 95% highway) and ski trips, etc.

When I bought the MO and drove it back to Reno from Berkeley the gas mileage was GREAT. I was getting 28-32 in some places according the onboard computer. I got about 500 miles out of that first tank of gas (which is what the dealership told me I could expect for an average tank of gas). It's been going downhill ever since.

I've had the MO for about 2 full months now, I have 2,142 miles on it. I do NOT lead-foot (occasionally of course, but 98% of the time I drive "reasonably"). I also do NOT "granny" it, meaning I don't bog the engine constantly. I also keep the A/C OFF (against the MOs insistent preference!) except when I'm running the defroster.

I understand that oxygenated gas is a factor. I have been burning only premium (91 is the best we can get here, no 93) fuel from Chevron or Shell since the day I bought the MO. According to Chevron's website, the fuel economy should only be affected 2%-3% with oxygenated gas. Hell, let's be overly pessimistic here and call it 10%. Even at 10% loss, I should be averaging about 18MPG city.

Over the last 3 tanks of gas I have averaged a stellar 12.2MPG. This is according to the onboard computer, and roughly confirmed by my own calculations. This is including some highway driving that should have helped boost the average a little. This is RIDICULOUS. I am getting less than 300 miles per tank of gas, usually about 280-ish. At 20MPG, I should be getting at least 400 miles on a 21.7 gallon tank.

I have read the threads where people have said it takes a long time to break in this engine and fuel economy gets better, but I haven't seen anyone with mileage THIS bad. I don't have any extreme circumstances that would explain this poor performance.

The local Nissan dealership has looked at the MO twice already, both times simply saying "there's no codes in the computer, be on your way citizen" and pretty much blowing me off.

So, here I am... imploring YOU, the great MO wizards of mechanical mastery, to please help me figure out what the hell is going on with my MO.

Could a faulty alternator affect mileage? (not being a mechanic please excuse me if I ask something stupid). I have seen a couple threads where it has been mentioned that a larger-capacity alternator can affect mileage as it requires more energy to operate. So, could an alternator that's not working properly put undue draw on the rest of the system to support it? I have not (thankfully) had the full-blown alternator failure, but I wonder perhaps if it's on the edge of death and this is a symptom. Can any of you think of any other factors that might be causing my MO to be guzzling gas like the oversized beasts of SUVs that I specifically avoided buying for this EXACT reason?!
 

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Mr. 3 K, 3/3/5. 5K,10/5/7
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Good Post. Lots of meat. NO CODES bothers me. That is really stinky milage especially considering your former numbers. Bag Oxygen senso (oh no codes) bad PVC valve ( don't know if it would show a code or not, maybe not) Spark timing has gone to H--- (Would a code show)

How do the exhaust pipe tips look, Clean or Black? Did you modify the intake in anyway CAI or something?

Answerign your question I would not thing the alternator could drop the milage by 1/2, it would have to be locked up to do that. IMO.

Gas milage does drop in the winter, warmups, pushing snow out of the way, added drag, etc. but in 1/2 wow.

I will do some thinking and ans as they say "I'll be back"
 

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I feel for ya. I have 1100 miles now and only got 16 mpg the last tank according to the computer and I thought that was bad. I just contributed it to still breaking it in but 12 mpg that is ridiculous. keep us informed.
 

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I feel for you. I have 30K and am getting 18 – 20 suburbia driving and 24 highway. Always been like this, from the beginning. And the mileage did not improve much after breaking in period.

My FX35 AWD which is driven by my wife in relatively heavy traffic (and she has a lead foot!!) gets 16 mpg. So 12 mpg for Murano stinks……….there is definitely something wrong……
 

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Discussion Starter #5
GripperDon

I have not done any modifications to the intake system or otherwise, it's all fully stock. When I go outside to go to lunch in about a half hour I will check the exhaust outlets and see how they look and report back.

I try to minimize warmups so as not to waste energy, and after reading an article in Road & Track about proper warm-ups, I have been sticking to a 30-60 second warm-up period. I would prefer to start 'er up and let 'er run for 10 minutes and get the inside nice and toasty, but I don't. :)
 

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I agree with the above that there has to be something wrong to cause gas mileage to be so bad. Maybe you need to try another dealership as I think that the ones that looked at it first wre only intersted in what a computer said.

Your note does not say that if they look at the fuel injectors or whether or not the transmission was acting normally. I just came through -35C weather and my fuel economy went into the toilet, instead of getting 12-13lt/100 KM I was averaging 20Lt/100Km. The only thing that I could see is that the engine RPM was at 2000 Rpm at 80 KM/h, instead of 1500 RPM, and that was city driving. I believe that the transmission fluid was super cooled with the low ambient temps and with 3 transmission oil coolers it is easy to see how that could happen and causing the transmission not to adjust the belt properly. Since the weather has warmed up (+10C today) the fuel economy is back up to 12.5lts/100 Km

If your fuel injectors are leaking, that I"m sure does not show up on the computer, and if they are it is possilbe you can smell a lot of gasoline in your engine oil.

Hopefully you can find some one that understands the term "TROUBLESHOOTING" as there are lots of things that could explain what the reason is for the poor fuel economy. Keep us posted
 

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Stoker,

the TC does not lock up if the transmission temp is low. I believe you experienced this phenomena.......
 

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Thanks Kris, that is what I saw and I was trying to put a name to it. All I know was the Mo was acting a little weird during that time.
 

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special-k said:

The local Nissan dealership has looked at the MO twice already, both times simply saying "there's no codes in the computer, be on your way citizen" and pretty much blowing me off.

While I am in no way condoning the dealer "blowing you off", there is a certain amount of truth to the "no codes" defense used by the service department. On Board Diagnostic 2 (OBDII) vehicles keep track of so many things related to engine management, it would boggle your mind. All in the name of proper emissions, I might add.
If your vehicle engine management system was amiss, something would surely turn up via a "check engine light".

Having said that, there are many other factors affecting MPG.
How is your tire pressure, for instance? How is your oil level? Do you do an excessive amount of idling? Do you warm the car up before driving off for the first drive? Ambient temperature lower than usual?
The list can go on and on. And the small things can add up.

Please verify that the vehicle MPG information being displayed is accurate as well. Sometimes the best solutions are the simplest!
:2:

PS My advice above is worth precisely what you paid for it:D


Best,
pino
 

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I'll go with a couple simple things that you can check.

Dirty airfilter? Shouldn't be the case with 2K miles.
Low air pressure in the tires? Set 'em at 35#'ish.

Also, with the leaky injector - it is very possible. If that's the case your oil level will be high and it'll smell like gas.
 

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Seems to me that with a leaky injector, the O2 sensor would get it and throw a code as the unburnt gas would not only go down in the crankcase, it would also go out the valves.

While agreeing that 12 MPG is terrible (I did about 16 in town when my Mo was new and I was breaking it in (Which meant varying the RPMS but NEVER accelerating hard),
here are some thoughts.


Somewhere between 9,000 and 12,000 miles my MPG went from 16 city/23 HWY to 18 City/ 23 Hwy. Note that Hwy did not improve. I drive at 75 or 80 MPH on the hwy. My "city" has a stop light every mile, not every block.


I didn't burn oxygenated gasoline. I didn't burn ANY gas that had anything in it other than 'normal" cleaners, octane enhancers, etc.. Isn't it 7-11 that sells a gasoline that has Corn Squeezins in it?

My ambient temps were always between 60 and 90 degrees during this time.

My tires were always at 33 Pounds cold.
I checked it daily at every corner for the first couple of weeks and then once a week.
I STILL check the pressure once a week, over a year later.


My altitude was at sea level, plus or minus 27 inches.

Florida is Flat.
Doesn't Reno have some roads that go straight up?

Like being told that you are going to die, but there is nothing that they can do............wouldn't you get a secoind opinion?


Homer




:D
 

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Mr. 3 K, 3/3/5. 5K,10/5/7
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ROGFMAO ( think that the right letters. for "Like being told that you are going to die, but there is nothing that they can do............wouldn't you get a secoind opinion?"

Homer you are the Man!

:2:
 

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I do a mix of highway and New York City Driving ( a range of about -1 to 90 miles an hour..and thats just 5th avenue :D ) and I get 13-14mpg. I am exteremly fortunate that my company pays for my gas so it never really bothered me....but should I really be getting 18+?
 

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I don't know about the majority of people... I have about a 15 minute commute on the highway with maybe 25% of the time on that highway in slow traffic. I typically am light on the gas pedal but drive between 70-80MPH. 30 seconds warmup time and use premium gas... since I've had the MO the avergage gas milleage is 19.4 MPG... my high MPG was 22 MPG and the lowest has been 16.5 MPG.

Has is alway been low even in the summer/warmer months? Have you tried a different gas station? Like others have said, check your tire pressire. Nissan tells us to inflate to 33 PSI.
 

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Mr. 3 K, 3/3/5. 5K,10/5/7
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Don't forget that tail tips inside check. :D
 

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There probably isn't anything wrong with your MO but rather with the Gas you are using. NV is a state which uses a "Winter Blend" gas (mix of regular gas and Ethanol) which WILL kill your gas mileage.

What has probably happened is the dealer filled you up from a tank they had in the back, which could have been from the summer, and now that you are filling it up around town, you are using the winter blend gas.

Here in CO, my average gas mileage in the summer is around 22 (mixed city and highway) but in the winter, it drops to around 17. If I am heavy on the pedal or it's been really cold out, it will drop to as low as 14.

Check the pump where you fill up at to see if this is the case. If so, you might want to wait until they switch back to a summer blend before worrying about problems with the engine or anything.

In CO, they typically start using the Winter blend around Oct-Nov and stop using it around April.
 

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My MO's faster than yours
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Check your tires!

My tpms was showing 34psi ATWA...and 17-19 mpg highway on the estimator. I bumped up the pressure to 38 cold. Now i'm getting 20-25mpg mixed driving. And I "have" a lead foot. I'm coming up on 17,000 miles and have had it for about 5 months. So i'm pretty sure Its broken in. The first 10,000 I was getting horrible milage. This was before my mods 14-16mpg. Luckily It got better. Hope this helps
 

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Mr. 3 K, 3/3/5. 5K,10/5/7
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The government says this:

"The U.S. Department of Transportation says that most drivers can improve fuel mileage by at least two percent by keeping their vehicle tires at the maximum recommended pressures. You can find the carmaker's recommended tire pressures in your owner's manual and on a tire decal or placard in the glove compartment or on the driver's door post, near a hinge. Today, most vehicle manufacturers recommend pressures that are equal or close to the maximum pressure molded into the tire sidewall. When you buy new tires, your best inflation pressure guideline is the maximum pressure molded into the tire sidewall. "

So I guess under inflation to the absolue max could give 5 to 10%

If you have 12mpg that would help you get up to 13.5Mpg. Does this float your boat? Not mine. I would continure to look for more causes, not to suggest not to take adavantage of the improvement form more tire pressure.
 

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I'm going to take possible issue with this line: "I also do NOT "granny" it, meaning I don't bog the engine constantly."

One of the things that was very counterintuitive to learn when I first got my Mo was that acceleration was happening even if the RPMs were not rising. I would just naturally keep dipping deeper and deeper into the go peddle to keep the RPMs rising as I accelerated.

I wasn't wailing on the poor thing, but there is simply no reason to spool her up to 3-4KRPM when accelerating up to any target speed unless you're in a hurry.

Once I learned to keep it in the 2-3K range (or even less if I'm really out to post high MPG numbers) and let the CVT do it's job and bring me to my target speed instead of with the engine, I gained back *several* MPG.
 

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Discussion Starter #20
Lots of great suggestions!

Well... let me say "thanks" to everyone who has posted suggestions and ideas. There are far too many posts to reply to indivicually so let me try and summarize my replies...

First off, MOreen (that's what i named 'er... lol) is back at the dealership this morning for another round of diagnostics. The first service writer I spoke to was incredibly unhelpful. He pretty much shrugged and said "too bad, unless there's a code we have nothing to work with." That irritated me. The second guy I talked to said "Oh, it's the altitude." OOOOkay, I can buy that a LITTLE. Reno is at 4,500 feet. However, I won't accept that elevation is causing me to get 40% lower mileage than advertised. *NO* other vehicle that I have ever owned has suffered THAT badly from the moderate altitude of Reno. Another service writer said "Oh... well... you can't go by the stickers. It says 20/24 but that doesn't mean anything. The V8 Titan says 14/18 and it usually gets about 10." Well, I'm certainly not going to accept that as an answer either.

GripperDon before I took it in I checked the exhaust tips as you suggested. They're not shiny clean but they're not overly built-up either, IMO. Just a little black in there. Engines do tend to run a tad rich at this altitude since the air is thinner... I had to rejet my motorcycle a couple of times (what a PAIN in the arse...) before I got a good balance. Perhaps a CAI kit would help balance things out a little by getting more air into the motor?

To those who suggested another dealer -- I'm in a tough spot. Reno has ONE Nissan dealership and no Infinity dealer. There's another Nissan dealer out in Carson City but that's inconvenient... I'll take the MO out there if I have to.

MightyMo I certainly understand what you're saying about how the MO accelerates. I'm not hammering on it to get the RPMs up high... I accelerate moderately in the 2K-3K area. By "not grannying it" I meant that I don't put around town at 1500rpm, which is entirely possible with the CVT. :)

I would hope/expect/assume (I know... I shouldn't assume anything...) that if the engine was running overly rich and wasting fuel, that the computer would detect this and either compensate or throw a SES light to have adjustments made. I would hope that the O2 sensor would detect if there was a leaky injector(s), as was mentioned, the fuel would be going out the valves wouldn't it?

I know that oxygenated gas has an effect, but like I previously posted it should not affect mileage THIS much. Chevron states 2%-3%, and I burn Chevron premium (which is 91 octane here not 93) and occasionally Shell. Nothing else has ever touched the MO since I bought it. This page shows our ethanol season and expected adverse effects on mileage.

The tires are 34psi cold. I checked this morning before heading to the dealership. I guess I could bump them up to 36-38ish, but as GripperDon said it probably won't help THAT much...

Someone mentioned Reno having roads that "go straight up".... LOL well it's not that bad. Reno isn't flat like Florida or my former home of Las Vegas, but it's no San Francisco either. We have a few moderate hills but really nothing severe.

If I missed anybody's suggestions I'll post more later. I'll let you know what I hear from the dealership when they call me.

Thanks again everyone.
 
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