Hi,
Mine is a 2013 Nissan Rogue S. I bought it used a month ago and have since been trying to identify the source(s) of its very bad fuel economy, so far to no avail.

The car has its own dashboard fuel economy gauge and the figure shown is routinely around 17 liter/100km (~14 MPG) for city driving. The official MPG figures for the car model are in the mid-20s. So my car is nowhere near where it should be in terms of fuel economy, even when taking into account the conditions of winter driving.

Since coming into possession of the car I have replaced with high quality parts the following:
1)The air filter
2)Engine oil & Oil filter
3)Coolant
4)All the spark plugs

To better diagnose problems I have bought a BlueDriver OBDII scan tool to record live data from my car.

I notice the following irregularities in the data that may point to the root cause(s) of my car's poor fuel economy. But I am not sure how to interpret them. I would really appreciate it if people from this community could help me out with their ideas.

1)Frequent and abrupt spikes in the voltages of the Air/Fuel (B1S1 Wideband O2) sensor when driving. The stoichiometric voltage of my car is 2.2 volts. The A/F voltage of my car would shoot up, always abruptly, to 4 or more volts (i.e. extreme lean condition) multiple times during a 20-minute drive. Lambda jumps with it.

In the following chart, AF sensor voltage is represented by the solid orange line, the Lambda value by the semi-transparent blue line.

https://i.stack.imgur.com/xrmw9.png


2)Every time there is a spike in the A/F voltage, the Short Term Fuel Trim would shoot up to compensate the lean condition. So in a short, low-speed 20-minute drive in the city the STFT would show multiple high trims (e.g. 25%).

In the following chart, the semi-transparent orange line is the AF sensor voltage, the solid blue line is the STFT.

https://i.stack.imgur.com/Ww8PQ.png


There seems to be some strong correlation between the two readouts, at least in the first half of the trip.

3)The scan tool indicates a permanent code of P0102 "Mass or Volume Air Flow Sensor "A" Circuit Low." I have tried swapping the Mass Airflow Sensor that came with the car with another used MAF sensor. The same bad fuel economy has persisted. I have not yet tried installing a brand new MAF sensor because of its cost. I would like to eliminate other possibilities before investing in a new MAF sensor.

I have plotted the figures for RPM and MAF gram/second on the same chart and it seems to me that the MAF sensor readout basically tracks changes in RPM, so it's not obvious to me that MAF is malfunctioning (though I don't know for sure whether the sensor under-reports the amount of air entering).

The solid orange line is the MAF g/s and the semi-transparent blue line is the RPM in the following chart.

https://i.stack.imgur.com/pmWDx.png

And it doesn't seem to me that I have a vacuum leak problem as the sudden spikes in the A/F sensor voltage occur during driving, and from what I have learned online the effect of vacuum leaks is usually more pronounced at idle and declines as the car accelerates.

I can't tell to what extent the sudden spikes in the AF sensor voltage and STFL are correlated with changes in MAF and/or RPM data.


Please let me know your thoughts. As for myself, the following questions are swirling around in my mind:
(1) What can cause the voltage of the A/F sensor to spike abruptly as in the case of my car? I have read in multiple places online that these wideband O2 sensors don't change their voltage suddenly like the traditional oxygen sensors do. Is it normal for AF sensors to have sudden spikes at all?

(2) In connection with question one, I have read somewhere that sudden spikes in AF sensor voltage may have to do with a shaky ground wiring. If this is a possibility, how do I go about confirming or ruling it out?

(3) Can my bad fuel economy really be caused by a bad MAF sensor, given the P0102 code? Is it theoretically possible that a bad MAF sensor is causing the kind of AF sensor voltage and STFT fluctuations seen in my car?

I'd appreciate any input from you. Thank you!

I had a permanent lean code after I installed a new air filter. The rubber on the new filter wasn't that thick and may have been causing a leak. Not sure if that was the problem or not.

I did a couple of things in this order:

Fuel system cleaner in gas tank
Cleaned mass airflow sensor
Cleaned upper O2 sensor
New Fram Air filter, thicker rubber

I did a drive cycle and the code went away and never came back.

I would drain and fill the transmission fluid also. Everyone says use Nissan NS2-3 fluid. I'm using Valvoline CVT fluid, 2500 miles so far, no problem. I have a 2011 Rogue with 135,000 miles on it.

If you have a MAF code then the computer is telling you the MAF is bad or the wiring leading to the MAF is bad. I would inspect the wiring first and if no problem was found I would change the MAF and this should solve a multitude of those issues you are reporting. The MAF measures the amount of air entering the intake, this affects the fuel trim the O2 sensors and other readings.

The most likely place for a bad spot in the wiring is at the connector, bent pin, loose/rotted wire into the connector, or a broken locking tab which allows the connector to jiggle loose. Use a small zip tie to fix this. However you don’t want to overlook the wires themselves, previous owners may have routed the wires differently than original and after some time a wire has rubbed through. If the wiring passes inspection.

Get a new high quality MAF. I am not sure what the oem part is for this vehicle, usually Bosch or hitachi. Pull your MAF and inspect it for the brand name, no name, means someone else has already replaced it with cheap crap and is likely why you’re having problems now. Do not get a cheap junk MAF they are just a waste of time and money, and often don’t work right out of the box. Which causes confusion and frustration when the problem isn’t fixed.

Rock auto has the actual Nissan part ($200+] and hitachi. They also have several other made in China junk maf’s. Avoid those.

Cleaning a MAF is a hit and miss deal. Sometimes it works , often it doesn’t.

Just remembered on my Quest I had that code. The problem was the intake hose between the airbox and throttle body. Remove it and check for cracks. Check all hoses that connect to the intake hose.

I replaced the hose, $130 dealer part, and the code went away. My Quest is a 2012.

TorJoe wrote: ↑

Sat Feb 29, 2020 3:59 pm

And it doesn't seem to me that I have a vacuum leak problem as the sudden spikes in the A/F sensor voltage occur during driving, and from what I have learned online the effect of vacuum leaks is usually more pronounced at idle and declines as the car accelerates.

Definitely sounds like the intake hose has cracks in it.

Rabidus: Thanks for your advice. I have installed a new Fram air filter. The one that came with the car was completely clogged with dust. But the post-air-filter chamber leading to the MAF sensor and the throttle was surprisingly dust-free when I opened them up for cleaning and inspection. But the P0102 code has remained even with the new air filter. And I will change the transmission fluid (and install an external transmission fluid cooler) after I have dealt with the lean spikes issue (which doesn't readily seem to me to be caused by transmission problems).

I have inspected the whole stretch of hose leading from the MAF sensor to the throttle intake. I didn't spot any obvious cracks, but I am not saying that I am ruling this out as a possibility. I may have to carry out a propane test to ascertain definitively (there are youtube videos showing how you can introduce propane at various places where there may be a leak; if your RPM suddenly goes up that means there is a leak and propane is getting sucked into the engine from there).

Thank you so much.

Rogue Jarhead: I am concerned about wiring, too. I have looked at the female connecting harness from the ECU side (which connects with the pins of the MAF sensor) and I notice that one of the five wires is a little twisted and part of the plastic wire insulation is flaking. The whole cable is wrapped in electrical tape and bundled with other cables that lead back to the ECU, presumably. Is it possible to just replace the cable leading to the MAF? That means I will have to cut through the electrical tape and separate the ECU-MAF cable from the other cables leading from the ECU.

Personally I am still wondering whether the MAF can cause the AF sensor to jump around like this. I understand that the MAF sensor can under-report the amount of air coming in, thus creating a lean condition detected by the AF sensor, which then prompts the ECU to order a positive STFT to inject more fuel for compensation. But then the MAF data readout seems to indicate that the MAF sensor is responding to increases and decreases in RPM. But, of course, a MAF sensor that responds to increases and decreases in RPM can still under-report the amount of air coming in, so I am definitely not ruling out the MAF sensor or its wiring as the source of my problem.

Thank you and please let me know if you or anyone else has any suggestions. Really appreciate it!

TorJoe wrote: ↑

Sun Mar 01, 2020 1:45 pm

I have inspected the whole stretch of hose leading from the MAF sensor to the throttle intake. I didn't spot any obvious cracks, but I am not saying that I am ruling this out as a possibility. I may have to carry out a propane test to ascertain definitively (there are youtube videos showing how you can introduce propane at various places where there may be a leak; if your RPM suddenly goes up that means there is a leak and propane is getting sucked into the engine from there).

I didn't "see" any cracks either, they usually split on the bottom or back from the heat.

With the car running, try to stretch apart different sections of the hose, flex it. You should hear if it sucks in more air or the engine should start to idle rough. Best way to check it is to remove it and stretch it apart.

I had this issue on a 2007 Kia Sedona and 2012 Nissan Quest. Drove me crazy until I figured it out.

If the check engine light is off and you just have the permanent code, you just need to do a drive cycle. If the check engine light came back on after you cleared it, then you still have the problem.


Sometimes your normal driving will clear a permanent code.

The drive cycle I did:

I drove over 25mph for about 50 seconds and then stopped for about 50 seconds. I think I repeated that 8 times or so and the permanent lean code was gone. Something I found on the web.

Prior to the drive cycle, I drove the car like I stole it for about 30 miles and the permanent code was still there, no check engine light.

The ECU will put a permanent code so you don't just clear the code and get emissions done without fixing the problem.

I just offered the tranny fluid change suggestion because CVT transmissions are prone to have issues. Manual says 60,000 miles. I'm changing mine 30-40,000.

Poor fluid will contribute to poor gas mileage with the CVT.

If you drive with O/D off all the time, you will not see the rated gas mileage.

The sweet spot for good gas mileage is keeping the rpm low, don't go over 3000 rpm. At 60 mph I'm cruising at about 1750 rpm.

Just plugged in the scanner and drove and my minimum was .4lb/min and high was 7.5lb/min bouncing up and down.

My car idles at .4lb/min.

I hit 16.5lb/min wide open throttle.

I run 93 octane.

I did take the intake hose out, stretch it, and look at it closely. But I haven't checked the intake manifold (post-throttle) for leaks.

As for computer memory of codes: I think there should be a way to completely clear it of all codes, including permanent ones, to see if the same ones pop back out in the case of persistent problems. I'll have to look into it how to do it for 2013 Nissan Rogue.

This is what I am thinking too: perhaps my car's poor fuel economy has nothing to do with the P0102 code and something else - perhaps deteriorating CVT fluid - is to blame. Maybe I have two different problems going on at the same time.

I have heard a lot of owners of earlier models of Nissan rogue (pre-2013) have experienced sudden loss of power and acceleration when transmission fluid overheated, or even blown the transmission altogether. I am pretty sure my CVT fluid is not fresh: its color is dark and dirty. I suspect the previous owner never changed it. Or maybe he did change it once and another change is past due. But if I am to change the CVT fluid I will make it part of the job of installing an external CVT cooler, because all the CVT fluid will escape anyway when you install an external cooler, so there is no point in replacing the CVT fluid first. And installing an external CVT cooler is kind of a big job for a novice DIYer like myself so I will exhaust other avenues of fixing my fuel economy problem first before moving to dealing with the CVT.


About the O/D overdrive: do you mean I should turn it on or off if I wish to have better gas mileage? I drive mostly in city at fairly low speed (rarely exceeding 40km/hr or 25 miles/hr) with lots of jack rabbit starts and stops. I know cars are most fuel efficient around 60 mph but unfortunately I can't help it - but still it should not be 14 mpg, I think, even in winter.


As for MAF reading. At idle, with my 2.5 liter engine, the readout is at about 3.7 g/s (~0.5 lb/min); when driving, when the RPM revs to about 2600 rpm, the MAF reads about 40 g/s (~5.29 lb/min). What is confusing is that sometimes your vehicle speed can be (relatively) high but RPM is low because you are cruising effortlessly. So my car can be at 50 km/hr (31 mph), but RPM is only 1300, and MAF reads 12 g/s (~1.6 lb/min).


Does your AF sensor reading (if your car has a wideband sensor) shows any spikes at all? If all is normal should a AF sensor gives sudden voltage spikes, such as when accelerating?

Thank you!

https://1drv.ms/u/s!AgKzwxJ6W_v8qQ8Dv20RNeGNEUsd

I was driving it pretty hard for this run.


As far as I know, you have to do a drive cycle to get rid of the permanant code, a scanner can't clear it. It's an emissions thing.

O/D is always on. My 2011 Rogue has a button on the side of the shifter that will turn O/D off at which point you can have some fun on twistie back roads. The rpm stays high and there's better throttle response, lower gas mileage is the tradeoff though.

If your rpm goes over 3000 when you take off in traffic and only hit 25 mph, you are burning a lot of gas.

I bought a tranny cooler but decided to wait on the install. I had issues with my CVT that was cleared up by the fluid change. I drive the Rogue pretty hard at times and it delivers. So far so good 2500 miles later on fresh fluid. The tranny mounted cooler sit up high enough where I don't think fluid would drain out to much if you removed it.

I drained and filled mine and then two weeks later I did it again. So I pretty much got all the bad fluid out. 5 quarts each time of Valvoline CVT fluid at $8 a bottle. I'll change it no longer than 40,000 miles now.

There's a drain plug, so it's easy to do, be sure not to over fill it. I would not wait if the fluid is as dark as you say it is.

What is confusing is that sometimes your vehicle speed can be (relatively) high but RPM is low because you are cruising effortlessly.

That's what the CVT(continously variable transmission) is all about.

Just saw your MAF chart. I don't think I ever reach 15.8 lb/min (~120 g/s), even on highway.

A case of 6 qt of Valvoline costs C$106 (~US$80) in Canada after text (everything's more expensive up here, damnit), so I want to limit the frequency of CVT fluid change.

But maybe I should do the installation of the external cooler sooner. I hear that it is difficult to get to the CVT cooler from above (under the battery platform) and that one may have to take the wheel on the driver's side off to get to the CVT cooler is from the side.


Others if you are reading: I am still interested to hear from you whether your AF sensor reading jumps up and down when driving with normal acceleration and deceleration. Should I expect the voltage to stay fairly constant at the stoichiometric voltage, or should I expect wide variations over the course of a trip? If yes, should these variations take the form of gently arcs up and down, or should they be sudden spikes ?

Thank you.

This was normal driving. It never stays constant. The long flat line was at idle while I got my phone out to take the picture.

As soon as you close the throttle the volts will drop to minimum and when you open the throttle, the airflow increases, how much is determined by how much you open it. But as soon as you raise your foot, the volts drops to minimum. The spikes you see are normal.

Rabidus: I think it's normal for the traditional oxygen sensor to oscillate between 0.4 and 0.9 volt. But I suspect that the wideband oxygen sensor (Air/Fuel sensor) may be a little different. I have read different things online. It seems that the voltage of an AF sensor should not fluctuate widely (or wildly) but should stick close to the stoichiometric voltage throughout, with fairly small deviations. I don't know.

By the way, do you notice an improvement in your gas mileage after you changed the CVT fluid?

I am hoping to hear from anyone who has knowledge - from personal experience or otherwise - about the connection between the state of CVT fluid and gas mileage. Some people seem to think that CVT fluid only affects gear-changing, but not other things like speed and fuel economy.

Thank you.

TorJoe wrote: ↑

Sun Mar 01, 2020 5:00 pm

Just saw your MAF chart. I don't think I ever reach 15.8 lb/min (~120 g/s), even on highway.

A case of 6 qt of Valvoline costs C$106 (~US$80) in Canada after text (everything's more expensive up here, damnit), so I want to limit the frequency of CVT fluid change.

But maybe I should do the installation of the external cooler sooner. I hear that it is difficult to get to the CVT cooler from above (under the battery platform) and that one may have to take the wheel on the driver's side off to get to the CVT cooler is from the side.

Regular price for Valvoline at Walmart is $8 a bottle here, other places have for over $10 a bottle.



I heard that this is exactly the same as genuine Nissan fluid, don't quote me on that though. I havent seen it locally.

Yes, if you remove the driver side wheel and a cover held on by push pins, the cooler is right there.

TorJoe wrote: ↑

Sun Mar 01, 2020 5:46 pm

Rabidus: I think it's normal for the traditional oxygen sensor to oscillate between 0.4 and 0.9 volt. But I suspect that the wideband oxygen sensor (Air/Fuel sensor) may be a little different. I have read different things online. It seems that the voltage of an AF sensor should not fluctuate widely (or wildly) but should stick close to the stoichiometric voltage throughout, with fairly small deviations. I don't know.

By the way, do you notice an improvement in your gas mileage after you changed the CVT fluid?

I am hoping to hear from anyone who has knowledge - from personal experience or otherwise - about the connection between the state of CVT fluid and gas mileage. Some people seem to think that CVT fluid only affects gear-changing, but not other things like speed and fuel economy.

Thank you.

My 2011 Rogue 2.5L engine recently got 27mpg on mostly back roads, no real stop and go to work and back. I didn't go over 3000 rpm for the whole tank of gas. It almost killed me driving normal. Last week I filled up and reset the mpg computer and it hit 33 mpg for 50 miles on the highway until I hit some traffic and it started to come down. This is on fresh fluid and 93 octane gas. I was shocked, it has never registered over 30 mpg at all before. Right now I'm at about 22 mpg driving like I stole it most of the time.

Last year on bad fluid and 87 octane gas I made three trips, Georgia to Texas and back, Georgia to Mississipi and back and Georgia to Louisiana and back. The best mileage I got was about 26 mpg all highway. The shortest trip was 400 miles oneway, longest was 1000 miles oneway.

The trip to Texas I ran into the tranny overheating problem on the way there. The tranny was fine after it cooled down. I made it to Texas and back on the bad fluid and didn't change the fluid until January, which was 6 months later.

I get much better gas mileage after the fluid change, part of it may be because of the higher 93 octane gas though.

The CVT doesn't have any gears, it's like a snowmobile or moped tranny, it has two pulleys and a metal belt. When the fluid gets up to operating temperature, that is when it is most efficient. When it is cold out, it takes longer for the fluid to heat up and it's not very efficient during that time.

Look up CVT transmission on youtube!

Rabidus: Ok I am sold. I am going to change my CVT fluid as soon as possible. It's winter now so my feeling is tranny overheating is less of a risk (than in summer when the ambient temperature is higher), so maybe the external tranny cooler can wait. The figures you cite are certainly dramatic: going from 26 to early 30s mpg after a change of fluid. Even if the difference it would make for city driving is likely less significant, it should still be noticeable.

But I am still concerned about the frequent +25% short term fuel trims that my scan tool registers. Do you experience relatively frequent 25% STFT? I mean they are spikes; the STFT doesn't stay at 25%, but they do spike up to 25% quite frequently. I am not sure that this is normal. And I am not sure if bad tranny fluid would create a lean condition.

Thank you so much for your input.

IMHO I believe the first generation Rogues get crappy mpg as they get older.

To be honest I don't really care about mpg and accepted it for what it is.

Moreover, I am just happy it runs great on it's original transmission

I remember when gas was almost $5 a gal back in 2008.

So happy it's about half now.

I did remember when it was 89 cents too.

I'm an old fart.

Short term fuel



Timing

So you do experience +25% STFT. I see in your chart that there were (only) two spikes to 25%. May I know who long was that trip?

I have read in multiple places where people say that STFT fluctuates but if you add STFT and LTFT they should not be of a magnitude greater than + or - 10%. That's what get me so anxious about my 25% spikes and that's what got me thinking that maybe the 25% spikes lie behind the poor fuel economy of my car.

If it is in fact natural for a normal functioning car to experience 25% spikes multiple times during normal driving then perhaps I should stop looking at them as related to my poor gas mileage.

Thank you!

My scanner is small, that was maybe a mile, if that. Keep in mind, I use. 93 octane, it burns better than 87 octane. The 2.5L engine has over 10:1 compression ratio.

If you only drive 25 mph or less, you probably just need an Italian tune up. I give my car an Italian tune pretty much everyday.

Use fuel cleaner every couple of tanks and see if it helps.

These ECU's control everything these days. In the second picture, my timing changed from -10 degrees to +40 degrees. It idles at about +10 degrees.

How does your Catalytic converter numbers look?

I monitored my STFT on the way home, mostly with cruise control on.

I went a half mile with two or three 25% spikes and then 2 miles with no spikes, with a high of 5%. On the hwy for several miles there was no spikes going about 65 mph with cruise control on.

It's a lot of hills where I live.

Just filled up the tank and the first 5 miles was on the highway. Reset the mpg computer and it was up to 33 mpg and then I got off and hit back roads. For my 23 mile drive home it's reading 28.7 mpg . It's raining, so I was driving normal.

I got 22 mpg on the last tank with a lot of spirited driving to and from work.

Hi,

I went to drive a long a stretch of road where I can reach 50 km/hr (~31 m/hr) more or less continuously for around 15 minutes and got the following figures. Please see what you can read from them. The figures pertaining to the catalytic converter and timing advance follow in the end.

MAF flow rate and RPM (The semi-transparent blue line is the RPM [generally under 2000]; the solid orange is MAF [hits 37~38 g/s at peak (~4.9 lb/min])
The two readouts seem to go up and down in tandem. But I think this doesn't necessarily mean MAF is not under-reporting.
MAF flow rate and Vehicle Speed (The semi-transparent blue line is speed [peaking at 60 km/hr (~37 miles/hr)]; the solid orange is MAF [peaks at 37~38 g/s; 4.9 lb/min])
I can see fairly strong correlation between the MAF reading and vehicle speed.
MAF flow rate and Short Term Fuel Trim (The semi-transparent blue line is STFT [multiple +20~25%]; the solid orange is MAF [peaks at 37-38 g/s; 4.9 lb/min)
There is some correlation between the two readouts; but not between MAF and the bunch of 25% STFT spikes between 1151 and 1253 (timeline).
RPM and STFT (The semi-transparent blue line is the RPM; the solid orange is the STFT)
As you can see, there are quite a few spikes to +25% STFT. RPM rarely exceeds 2000 RPM. Otherwise I don't see any obvious pattern of correlation between the two.
Vehicle Speed and STFT (The semi-transparent blue line is speed in km/hr; the solid orange is STFT)
It seems that all the STFT 25% spikes occurred only when vehicle speed was at or above 45 km/hr (~28 miles/hr). Is there a reason behind this?
Air/Fuel (Wideband O2) Sensor Voltage and STFT (The semi-transparent blue line is the AF voltage; the solid orange is STFT)
There is a clear correlation between AF sensor voltage and STFT, with lean AF voltages (going all the way to 4.5 volt) prompting high positive STFT (20~25%). The question is why the AF sensor voltage gives lean spikes? Is this normal?
Air/Fuel (Wideband O2) Sensor Voltage and RPM (The semi-transparent blue line is the AF voltage; the solid orange is RPM)
I don't see any correlation between the readouts of AF sensor voltage and the RPM, just as I don't see any correlation between STFT and RPM.
Air/Fuel (Wideband 02) Sensor Voltage and Post-Catalytic Converter Oxygen Sensor Voltage (Solid blue is AF sensor voltage; solid orange is post-cat O2 sensor voltage)
The two readouts fluctuate in direct inverse relationship with each other. From what I have read online, this seems to point to a dysfunctional catalytic converter. A normal catalytic converter should burn all the excess fuel/impurities such that the post-cat oxygen sensor maintains a fairly stable voltage somewhere between 0.45 and 0.9 (mine jumps up and down between 0 and 0.9).

But whether this has anything to do with my poor fuel economy is another matter. I hear that a blocked catalytic converter can cause poor engine performance and therefore poor fuel economy. But a catalytic converter that is not working properly is not necessarily a plugged up one. Given the inverse relationship between the AF sensor voltage and the post-cat O2 sensor voltage I am getting, it seems that the exhaust is able to pass through the catalytic converter. It's just that catalytic converter is not treating the exhaust as it should.
Barometric Pressure, Calculated Engine Load, and Catalyst Temperature
I am assuming that these are the data related to the catalytic converter. I don't know how to interpret them so I am posting them without comment.

The peak temperature recorded at 527.6 degree Celsius is equivalent to 981.68 degree Fahrenheit (not particularly high?).
Finally, timing advance for #1 cylinder (is this the same thing as SPARKADV TIMING?)
If my charts all look acceptably normal, and yet I am getting bad fuel economy, then I may have to conclude that there may be problems with the fuel-supply side (bad fuel pump/blocked fuel filter/bad fuel injectors etc), or that perhaps it is the bad CVT fluid that is acting up.

I hope that people more experienced than me with charts can pick up clues that I have missed.

One final thing - this maybe another clue - every morning, at least in the first couple of minutes of driving my car (it's winter now), it gives a loud, continuous, high-pitch sound somewhere from below. The sound always ceases at some point (I don't know how long into driving does it usually stop as I can't hear clearly anymore once I am on the road where there is a lot of ambient noise); when I come back to my underground parking space at night and I roll down my window I won't hear the sound. I hear the sound only when the car is moving. It stops when the car stops. Can this be the sound of my car's CVT transmission? Or can it be sticking brakes (which can explain my bad fuel economy; but if it's sticking brakes do they make a high-pitch sound that always stop once the car has been running for a while?)?

I am sorry this post has gone on for far too long. If you have read it through, thank you so much for bearing with its length!

Thank you.

I like to say that I was pleasantly surprised that I gained an extra 1 mile per gallon after using fuel/injector cleaner.

Usually just use the to prevent codes.

I have started putting Lucas Fuel Treatment in with every full-tank refuel. I don't know how many full tanks I have to go through before seeing an impact if my fuel injectors are in fact dirty enough to benefit from it.
https://lucasoil.com/media/k2/galleries ... 00x950.jpg

Wow...that's a lot of info. Your catalytic converter seems to operate like mine. At idle the downstream numbers is about .5 continously and between 0 and .9 while driving.

Looks to me that your engine is fine. I'm no expert though.

One final thing - this maybe another clue - every morning, at least in the first couple of minutes of driving my car (it's winter now), it gives a loud, continuous, high-pitch sound somewhere from below. The sound always ceases at some point (I don't know how long into driving does it usually stop as I can't hear clearly anymore once I am on the road where there is a lot of ambient noise); when I come back to my underground parking space at night and I roll down my window I won't hear the sound. I hear the sound only when the car is moving. It stops when the car stops. Can this be the sound of my car's CVT transmission? Or can it be sticking brakes (which can explain my bad fuel economy; but if it's sticking brakes do they make a high-pitch sound that always stop once the car has been running for a while?)?

My CVT had or developed a whining noise while driving, I thought it was a normal thing with a CVT, but it was gone after I replaced the fluid. My fluid was pretty bad.

My advice would be to drain and fill the CVT fluid.
And throw some fuel system cleaner in the gas tank, I've only did it once. And see if that helps. Be sure to use "CVT"(needs to say CVT on the bottle), and do not overfill.


My wife drives our Nissan Quest 3.5L with CVT, she does a lot of short distance low mph trips and gets poor gas mileage. It doesn't get as good mpg as the Rogue anyway though. I drive the Rogue 23 miles to work and only about 7 minutes is in a little traffic.

For your driving conditions, that may be your mileage. With fresh fluid and warmer weather. your mpg may improve. I would wait and see before changing fuel system parts.


As I mentioned earlier, my engine rpm is a little higher than normal, in the cold mornings, until the CVT fluid heats up. My engine would be at operating temp first and I could tell my CVT fluid isn't there yet.

It doesn't get much colder than 30ish degrees Fahrenheit overnight and gets warmer during the day. Winters here in the southeast US are not typical winters. We have 70F degree days quite a bit. Being that there are no gears in the CVT and the metal belt needs fluid temperature to be good, I'm sure the cold temperatures in Canada affects a CVT more than it would a regular auto transmission with gears. The belt needs the fluid, not as a lubricant, but more for friction. Something about the molecules in the fluid heating up and bonding to create friction so the best can push the pully.

Bad CVT fluid is not good and cold temperatures may make bad fluid worse.

I love the CVT transmission and how it performs. I think a lot of its issues comes from poor maintenance. pulley. Some other model Nissan's are programmed with fake shift points to feel like a auto transmission with gears, I think that defeats the purpose of the CVT.

Hopefully, If you change the fluid and your mileage gets better, and then gets better in the summer, you'll have the answer.

I just changed my rogue's CVT fluid today. It's pitch dark and very viscous (whereas Valvoline, when it's brand new, is transparent with a yellow hue and perfectly runny). I shone a flash light from the other side of the measuring cup and I couldn't see any suggestion of light from my side. I hope this will improve my gas mileage, if only by a noticeable little bit.
Thank you to all who have chipped in with their comments and advice!

I will periodically come back to see if anyone has more to say. Thanks!

TorJoe wrote: ↑

Wed Mar 04, 2020 11:52 am

I just changed my rogue's CVT fluid today. It's pitch dark and very viscous (whereas Valvoline, when it's brand new, is transparent with a yellow hue and perfectly runny). I shone a flash light from the other side of the measuring cup and I couldn't see any suggestion of light from my side. I hope this will improve my gas mileage, if only by a noticeable little bit.

IMG_20200304_123421.jpg

Thank you to all who have chipped in with their comments and advice!

I will periodically come back to see if anyone has more to say. Thanks!

Yeah, that's nasty!

I would like to know if your mpg gets better after the change.

I just learned from an old thread from this forum that there is actually 7.9 quart of transmission fluid in a Rogue and that by simple draining I have gotten rid of only around 4.9 quart of the bad fluid (4.9 quart was what came out when I unplugged the transmission pan). That means there is actually still 3 whole quarts of bad fluid now mixed in with the new fluid!!

I forgot to include the link to that old thread I referred to:
valvoline-cvt-fluid-t601356.html

TorJoe wrote: ↑

Wed Mar 04, 2020 6:40 pm

I just learned from an old thread from this forum that there is actually 7.9 quart of transmission fluid in a Rogue and that by simple draining I have gotten rid of only around 4.9 quart of the bad fluid (4.9 quart was what came out when I unplugged the transmission pan). That means there is actually still 3 whole quarts of bad fluid now mixed in with the new fluid!!

Shouldn't be an issue, but that's why I drained and filled mine twice, second time two weeks later. Next time, 30,000 miles for next change, I'll only do it once.

How many miles are on your car?

My car has almost 140000 km (~87000 miles) on it.

Well, after changing the CVT fluid, the high whining sound when I first start the car in the morning has gone away. And I feel the car has more power and runs more smoothly and with less rattling and shuddering (there was a bit before). But the very regular 25% STFTs persist, and I don't think it's normal. I notice that these STFTs occur only when my RPM goes over 1500 and when vehicle speed exceeds 30 miles/hr. So when I cruise on the highway I have these very regular 25% STFT spikes. I will get to the bottom of this - eventually.

But if only for getting rid of that whining sound in the morning, the change of the CVT fluid was totally worth it.