CVT Behavior

[TomNJ]

I took my 2008 2.5 SL down to the Blue Ridge mountains of southern Virginia last month for vacation. There were no straight or level roads there and I was constantly snaking up and down the mountains. I noticed that when going down hill, my RPMs would jump from about 1,500 - 2,000 to nearly 3,000, and the CVT would whine slightly as if dropping down a gear. I took to shifting into Neutral for the extended down hill runs and could feel the load lift from the engine as the RMPs dropped to about 800 and speed picked up. I was careful to let the RPMs drop down to near 1,000 before shifting back into Drive so as to not jolt the trans.

After about two weeks, the CVT began whining loudly and chattering slightly when cold, so I inspected underneath and found the undercarriage wet with oil behind the CVT. I immediately took it to the nearest Nissan dealer 30 miles away in Martinsville. They diagnosed a bad axle seal and replaced it, thus fixing the problem. They said I was about one quart down on CVT fluid (still on the dipstick) and that the seal problem (misalignment) was caused by Nissan during assembly. They also said the apparent down shifting of the CVT during downhill driving was normal, acting as an engine brake.

I have noticed some occasional drops of oil on the driveway since the car was new (now has 7,300 miles). But as one who is distrustful of coincidents, I'm wondering if my coasting in Neutral could be related to the axle seal problem.

Is there any harm in coasting in Neutral during extended downhill driving so long as you don't jolt the CVT when returning back to Drive?

And is it normal for the CVT to downshift during downhill driving in Drive?

BTW, kudos to Jim Mills Nissan dealership in Martinsville, VA. They were very friendly and efficient!

Thanks!

TomNJ

[LongBeachCoupe]

Hey man! Welcome!

Just because the cvt is finicky.. i wouldnt be touching the shifter while your moving... ever.

For ZYX reason, if i put my car in neutral, the key fob button flashes, and it disconnects the fuel line pretty much...

[n9gux]

The community where I live is on a pretty steep grade and I too have noticed the apparent "down shift" it acts as an engine break to maintain speed.

[bina12834]

always shift into neutral when going down a steep hill

[marlin29311]

always shift into neutral when going down a steep hill

wtf are you talking about. That's probably the worst thing you can do for your car. Not only are you putting your car at risk for stalling out, you are also removing braking power by disengaging the transmission. That is quite possibly the dumbest thing I have heard in a while...

To the original point, you shouldn't be switching out between N and D when driving at all. The car is designed to engine brake like that and the whine is probably just the 2.5 engine making it's normal noise.

[missmedude]

although it is bad for your car, i thought it saved gas also

[mcheddadi]

wtf are you talking about. That's probably the worst thing you can do for your car. Not only are you putting your car at risk for stalling out, you are also removing braking power by disengaging the transmission. That is quite possibly the dumbest thing I have heard in a while...

lol I always shift in neutral down a hill, saves buckets of fuel, leaving it in gear is what will cause premature wear, HA!

[marlin29311]

you also have a MT bud

[maxentropy]

what marlin stated is true-- for CVT it's probably not a good idea to switch to neutral.

CVT has built in "grade logic" (or whatever Nissan calls it) which basically works much like a truck's J-Brake by prohibiting the car from gaining speed by changing the gear ratio. Your RPMS will go up, but the fuel consumption does not as the car is simply downshifting for you to prohibit more speed.

Myself, on steep hills I will downshift myself. This is perfectly safe on CVT-- if you are a moron and shift wrong you will know it as the car will jerk a bit. Try practicing (it works a lot like a manual without the clutch).

Good luck!

[dangeris]

I do it all the time! I'm so used to driving my car in manual mode I forget it's automatic

[adidas2go]

what marlin stated is true-- for CVT it's probably not a good idea to switch to neutral.

CVT has built in "grade logic" (or whatever Nissan calls it) which basically works much like a truck's J-Brake by prohibiting the car from gaining speed by changing the gear ratio. Your RPMS will go up, but the fuel consumption does not as the car is simply downshifting for you to prohibit more speed.

Myself, on steep hills I will downshift myself. This is perfectly safe on CVT-- if you are a moron and shift wrong you will know it as the car will jerk a bit. Try practicing (it works a lot like a manual without the clutch).

Good luck!

Trucks Jake brakes have nothing to do with gears, it holds the engines intake valves shut to prevent power from being transfered through the drivetrain.

I never leave my car in auto, it is in manual 100% of the time when I drive. I also use the downshift technique when going down grades

[Keyan]

I never leave my car in auto, it is in manual 100% of the time when I drive. I also use the downshift technique when going down grades

Is that why on your youtube vids everyone thinks you are running it on a MT? I would think you'd want the turbo spun up to max and the engine parked in the max performance range, but maybe it behaves oddly with the turbo. Or is the turbo already going full tilt in that RPM range anyway?

[sumatrancub]

Banned as per Marlins91547822336 request.

[marlin29311]

n9gux - please contact me... you know who .. and you know how..

[G_whizz]

Aren't you at least curious...really?? Ban so fast??

[marlin29311]

lol - not really. I guess i've just had it with spammers lately...this is just bad. I would have more respect if they said "COME BUYZ MY M@D HAWT TYTE JDM SKYLINEZZZZ"

[G_whizz]

LOL..

Ok..I will drop the ban hammer just for you brohem.

[Beancooker]

Sounds more like an ex-girlfriend to me...

[marlin29311]

Banned as per Marlins91547822336 request.

I don't have that many numbers after marlin!!! lol

merci!

[adidas2go]

Im lost