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Old 07-19-2008, 03:55 AM   #1
xsicdn
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Nissan C-V-Transmission

I'm still experimenting with the Nissan Continuous Variable Transmission; I've driven it about 600 miles so far. I haven't come to a conclusion yet whether I should just leave it in 'D' and let the automatic transmission do its thing, or to put it into the manual mode and use the up/down shift paddle.

For those not familiar, the Nissan CVT has a mode where the shifter lever is moved over into a special 'manual' zone. When in this zone, tapping the shifter in one direction shifts up, and in the other direction shifts down. Since it's a continuous variable transmission and there are therefore no distinct gears, the paddle moves the transmission belt into 6 preset positions. When the car comes to a stop, the shifter automatically downshifts to 1.

I find in 'D' that it tries to keep the RPM around 2000. That's fine most of the time, but slowing into a turn it seems to drop below 2000 and labors the engine trying to gently accelerate out of the turn. If I goose the throttle it jumps into action, but that's not what I'm after ( gas costing what it does these days! ). If I take manual control, I can downshift to 3 just before a turn and have lots of pep to accelerate out of the turn with the RPM up around 2500-3000. The automatic mode is just fine from a stop accelerating to driving speed; it's just the turns that are sluggish.

So far, I've been using the manual mode if I know I'll be in a situation with lots of turns, then push it back to automatic when I get to the long straight sections or to the highway. The only down-side with this is sometimes I get distracted waiting at a light and forget that I need to upshift until the engine starts getting a little noisy over 4000 RPM in 1st gear.

Does anyone have any experience with the CVT? Have you done much with the manual mode? Any thoughts? Don't tell me I should have bought a manual transmission if I wanted control; I know that! Been there, done that for decades.
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Old 07-19-2008, 07:44 AM   #2
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stick wit the manual it will increase you MPG
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Old 07-19-2008, 08:52 AM   #3
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Keeping your RPM too low will result in bogging and even more fuel consumption from what I hear.

What Nissan is this?
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Old 07-19-2008, 02:21 PM   #4
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Originally Posted by newyorker
Keeping your RPM too low will result in bogging and even more fuel consumption from what I hear.

What Nissan is this?


It's an Altima 2.5SL. It has an instantaneous readout of fuel economy and an average trip speed / fuel economy ( resettable ). Once I get the hang of this strange shifter I'll start taking down the numbers along the commute to work. In a few weeks the daily variances in traffic flow should have averaged out and I will see which mode gets better mileage. I'm actually willing to sacrifice a slight bit of fuel economy for a better 'feel'.
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Old 07-19-2008, 07:25 PM   #5
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I've heard the same thing but always wondered if it was true. On my ride home from work I get off the highway and drive about 10mi down a 50mph road. Generally I leave it in 5th and put the cruise on at 53-55. I've noticed when going up a steep the hill the motor doesn't really struggle, but the peddle is about floored from the cruise. I always wondered if I'd be better off downshifting so it wouldn't be peddled so deep and then going back into 5th downhill and on the flats.
The car got 31mpg last time I checked it so either way I wasn't too worried about it.
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Old 07-20-2008, 04:31 AM   #6
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Quote:
Originally Posted by xsicdn
It's an Altima 2.5SL. It has an instantaneous readout of fuel economy and an average trip speed / fuel economy ( resettable ). Once I get the hang of this strange shifter I'll start taking down the numbers along the commute to work. In a few weeks the daily variances in traffic flow should have averaged out and I will see which mode gets better mileage. I'm actually willing to sacrifice a slight bit of fuel economy for a better 'feel'.
I doubt you will notice any significant difference in fuel economy from manually shifting, the computer usually wont let you get into higher gears annyway, ive experimented quite a bit with different cars at work. The only thing I have found close to a full manual was BMW's SMG system, which is a $7,000 option IIRC.

Basically, you cant get into 6th gear at 30mph with some of these Tiptronic and Steptronic transmissions, as you can with a full manual. The reason for this is that when you are in that low of a rev range, you are actually burning more fuel because you have to push the pedal harder to get moving and therefore are putting more stress on the engine and actually reducing fuel economy. The car's ECU knows this and doesnt let you do what you really want.

I would be more concerned with safety, you may find yourself worrying so much about your shift points that you will be looking at the tach more than the road.
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Old 07-24-2008, 07:36 PM   #7
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Originally Posted by newyorker
I doubt you will notice any significant difference in fuel economy from manually shifting, the computer usually wont let you get into higher gears anyway..... Basically, you cant get into 6th gear at 30mph with some of these Tiptronic and Steptronic transmissions, as you can with a full manual. The reason for this is that when you are in that low of a rev range, you are actually burning more fuel because you have to push the pedal harder to get moving and therefore are putting more stress on the engine and actually reducing fuel economy..

It's the opposite I'm trying to do; I want to keep the revs up between 2500 and 3000 when cornering so that it doesn't bog down when I try to accelerate out of the turn. So far, I've found that the automatic setting takes the turn in what amounts to the 4th "gear" setting and the rpm drops down well below 2000. If I manually shift it into 3rd position before the turn, I can use the engine braking to slow down and then it's a much smoother accel with the rpm over 2500 coming out of the turn. I shift up when it gets to 3000 RPM unless I know there's another turn just ahead.

Quote:
I would be more concerned with safety, you may find yourself worrying so much about your shift points that you will be looking at the tach more than the road.


How many manual transmission drivers look at the tach to know when to shift? You just feel when it's right ( use the force Luke ). I'm only quickly glancing so that I can report the numbers here.


In any case, my observation so far is that the fuel consumption has risen slightly from ~7.6 L/100Km to ~8.2 L/100Km ( I can't be bothered to convert to MPG ) an 8% increase. I can't say positively it's because of my manual shifting or because of all the road construction that keep me idling in slow moving traffic. More testing needed.
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Old 07-25-2008, 03:18 AM   #8
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I watch the tach to know when to shift. I kinda have to, it boogies from 4K to 7K.
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Old 07-25-2008, 08:52 PM   #9
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I always watch mine, my gearing is hella short so I have trouble keeping it under 4krpm even when watchingt he tach
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