Rogue CVT compression braking

[mdecicco]

I recently purchase an 09 Rogue S AWD. I was quite surprised to see that the CVT transmission is set up to very aggressively use compression or engine braking whenever the vehicle descends even a modest hill. Any time you take your foot off the gas and the vehicle continues to accelerate (example: going downhill) the CVT transmission attempts to slow the car by using the engine as a brake. I've had the revs jump from 1500rpms to as much as 3500rpm as the transmission tries to slow the car. Not only is it aggravating but it makes the car much louder than necessary and I'm sure that it negatively impacts fuel economy. Why wouldn't you let the car coast down a hill? No other automatic transmission that I have ever driven was designed to employ compression braking as experienced in the Rogue. Can anyone tell me what Nissan's logic might be behind this decision?

[philipa_240sx]

Firstly, welcome to the NICO Rogue Forums mdecicco!

To answer your questions,

Not only is it aggravating but it makes the car much louder than necessary and I'm sure that it negatively impacts fuel economy.

Not really. When the vehicle is coasting or decelerating in the manner you describe, the engine uses little to no fuel. This is normal for modern fuel injected cars... the engine is almost 'turned off' during deceleration.

Can anyone tell me what Nissan's logic might be behind this decision?

Supposedly Nissan did this to counter complaints with the 1st gen Murano that did not have any braking effect at all. Some have found it annoying. I actually find engine braking quite useful to maintain speed instead of applying the brakes.

[harryg]

Yea i enjoy this feature because if it didnt have it i would have to "ride" the brakes all the way down the hill...this helps maintain the speed...ive seen a few ppl getting pulled over for going to fast because they just let the car coast down a hill therefore their speed builds up too fast (and cops these days will pull you over for minor things)

plus it helps save the brakes from wear

[ncsu]

Not really. When the vehicle is coasting or decelerating in the manner you describe, the engine uses little to no fuel. This is normal for modern fuel injected cars... the engine is almost 'turned off' during deceleration.

This became a large topic of discussion on another board. Basically when 0 input from the throttle the engine essentially turns into a large air pump - well an air only pump since an internal combustion engine is nothing but an air pump. I have tested this with my Scanguage II on my Honda. It will read 9999 mpg when there is no throttle input. This is the same reading it has when the engine is off. At idle the reading is 0.

This is where the Hypermilers do things that are both dangerous/illegal and inaccurate. Killing the engine going down hill does not save any fuel, it possibly uses more at startup.

[mdecicco]

About the gas mileage - I agree with you - the engine is not burning more fuel when compression braking but the car is traveling less distance on that same amount of burned fuel. Coast down a hill, no compression braking, the car might travel 500yards. Coast down that same hill with compression braking and the car will stop far short of 500yards. As others have pointed out this holds true as long as one is willing to let the car accelerate (possibly exceeding posted speed limits). I don't know of any other automatic transmission (other than Nissan's CVT) that is set up to use engine braking - do you?

[philipa_240sx]

I don't know of any other automatic transmission (other than Nissan's CVT) that is set up to use engine braking - do you?

Automatic transmissions do provide a small degree of engine braking... it's just not as pronounced.

The CVT has the ability to downshift and maintain a constant speed by varying the gear ratio and hence degree of engine braking. I've tried it on several occasions and on all but the steepest hills the Rogue can maintain a constant speed. From the service manual:

Quote »DOWNHILL ENGINE BRAKE CONTROL (AUTO ENGINE BRAKE CONTROL)When a downhill slope is detected with the accelerator pedal released, the engine brake will be strengthened up by downshifting so as not to accelerate the vehicle more than necessary.[/quote]If the engine braking really bothers you, discuss it with the dealer. There is an option within the CVT computer to completely disable it. Assuming the dealer is willing to do it and you are willing to pay for the labor.

[Pescakl1]

Like you, I am a little bit annoyed about this "too much" engine braking. I would have preferred a lighter version, less pronounced (but I understand that Nissan wants to keep the speed the same to avoid us getting speeding tickets).

Like Phillip said, there is a way to remove it but then, you won't have any engine braking AT ALL (almost like free wheel), and bye bye brakes, that is why I decided not to do it.

If you have the paddle shifters, what you could do is go to manual mode and select the highest gear to get the less engine braking. For me unfortunately, I will still have to slow down too much to my taste.

It would be nice if Nissan could add a button on the shifter to remove temporarily the engine braking when we wish to.

[mdecicco]

I agree, some engine breaking is good but it is much too aggressive on the Rogue and I am guessing it would be a mistake to have it completely disabled. It falls into the same category as the button on the shifter to disengage the overdrive - way to aggressive , again!

[koolyce]

For me, I like how it works because when I go downhill and stop using the gas pedal, if my speed was 100km/h, and the end of the hill, my speed is mostly the same.

So the breaking is not so aggressive, is more like "Hey dude, we don't go faster then your cruising speed".

for that.

[bboard]

hmmm... I don't really if I'm a fan of this engine braking or not. I've grown kinda used to it especially when I go down the same hill everyday... I just subconsciously paddle to 5

My friend's Matrix auto transmission also has engine braking, but activates it when he steps on the brake the stop time after going down a hill.... This I thought is more appropriate way of doing it vs Nissan's method

[mdecicco]

It seems this is becoming simply a matter of preference. Some like it, some don't. I give it a strong thumbs down. If I wanted my engine revving at 3500 rpms when going down a hill I would have bought a car with a standard transmission. Thanks for your comments.

[crayb]

Funny thing, I was just thinking today as I sat in traffic, inching forward, how I hardly had to use the brakes at all, just release the accelerator and coast until stopping, the Escalade in front of me was pounding the brakes every few seconds, not me.

I hated the CVT at first, purchased in June 09, but I have since grown to LOVE it. Gives instantaneous power, less braking, smoother "shifts". I seriously wanted to return my Rogue 2-3 days after purchase because it felt weird, like an electric car!

Give the CVT a chance, maybe it'll grow on you. I'm a big fan of manual trans but in more and more areas they are becoming more troublesome than just letting the slush box do all the work. One day of driving the Miata to work and I have a sore left knee.

Ray

[ncsu]

Funny thing, I was just thinking today as I sat in traffic, inching forward, how I hardly had to use the brakes at all, just release the accelerator and coast until stopping, the Escalade in front of me was pounding the brakes every few seconds, not me.

I hated the CVT at first, purchased in June 09, but I have since grown to LOVE it. Gives instantaneous power, less braking, smoother "shifts". I seriously wanted to return my Rogue 2-3 days after purchase because it felt weird, like an electric car!

Give the CVT a chance, maybe it'll grow on you. I'm a big fan of manual trans but in more and more areas they are becoming more troublesome than just letting the slush box do all the work. One day of driving the Miata to work and I have a sore left knee.

Ray

This is why my other car is a 6 speed. I get the best of both worlds - the manual for zipping arround the country side and the auto for in town driving.

[trusty_getto]

This is interesting. I just had my Rogue in for routine service, and at 75,000 miles, I am still on the original brake pads. Service guy told me it looked like around half the braking material was still there. Could it be the engine braking that is saving brake material. I have never gone this far on a car without new brakes pads.

[Couz]

Can someone explain what engine braking is?

What does it feel like?

[mdecicco]

The simplest explanation - normally we use the engine to accelerate but it can also be used to decelerate thus the name engine braking. Easiest to understand in a standard transmission vehicle. Leave the car in gear, take your foot off the gas, as the engine rpm's drop you will also feel the car slow. The engine is trying to slow to idle rpm's and because it is still in gear and directly connected to the drive wheels it is also slowing the car. In an automatic transmission this phenomenon still occurs but in most cases, to a much lesser degree because an automatic transmission allows for some slippage between engine and drive wheels. In the Rogue, apparently by design, the automatic transmission aggressively uses engine compression to brake, for what reason I can not understand! As you can see here , there are apparently some people that seem to like it and some that don't.

[Couz]

The simplest explanation - normally we use the engine to accelerate but it can also be used to decelerate thus the name engine braking. Easiest to understand in a standard transmission vehicle. Leave the car in gear, take your foot off the gas, as the engine rpm's drop you will also feel the car slow. The engine is trying to slow to idle rpm's and because it is still in gear and directly connected to the drive wheels it is also slowing the car. In an automatic transmission this phenomenon still occurs but in most cases, to a much lesser degree because an automatic transmission allows for some slippage between engine and drive wheels. In the Rogue, apparently by design, the automatic transmission aggressively uses engine compression to brake, for what reason I can not understand! As you can see here , there are apparently some people that seem to like it and some that don't.

Thank you for that...much appreciated.

One thing I do notice is when I take my foot off the gas the car does tend to let up quicker than you would think....but it doesn't bother me that much as I'm not an agressive driver.

[mdecicco]

One thing I do notice is when I take my foot off the gas the car does tend to let up quicker than you would think....

Well said, that's it exactly! Try it going down a steep hill!