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Discussion Starter · #1 ·
I have a question about the computer in the cube.... First, Is the cube truely a "Drive by wire" accelerator?
Second, If so, then what is a good simple explanation of the total functions of this electronic communication between the gas pedal, and the engine, and the transmission (CVT)?
I remember before getting my cube, that I read in some of nissan's literature that the Cube's CVT can learn your driving habits, and adjust to your driving style. What is with this? How? ???
 

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Hi Relic,

This article on wikipedia has a general explanation of what the drive-by-wire throttle system does:
http://en.wikipedia.org/wiki/Electronic_throttle_control

Unfortunately that article is not a simple explanation. To really understand what is happening you would need to be an electronics engineer and a embedded systems programmer... I am just a software engineer, but I have a general understanding of what these systems do, but I can't explain exactly what is happening. So here is my take on the "simple" explanation: (sorry in advance for the long explanation!)

Our Cubes have a pretty complicated system to control the engine. The Cubes with a CVT transmission have even more complexity. First, it is the computers job to keep the engine running. The computer controls the spark plugs, the fuel injectors and the throttle body (sometimes called the throttle butterfly) and it controls the gear ratio of the transmission as well as whether the torque converter is engaged or not. Additionally it measures the speed of the engine, the speed of the car, the speed of each wheel indipendant of each other, and the emissions of the engine as well as the throttle control (gas pedal) and the breaks.

What happens when you press on the gas pedal depends entirely on what the car is doing at the that moment.

To illustrate: if the Cube is at rest pressing the gas pedal will cause the computer to increase the engine RPM by opening the throttle body, injecting more fuel and changing the gear ratio of the transmission to cause you to accelerate.

Once you are up to the speed you want to be going you would normally back off a little on the gas pedal. The computer senses that you have done so and usually locks the torque converter to improve gas mileage.

Say you want to pass the slow moving Buick in front of you. Generally you mash down on the gas pedal to indicate you want to speed up. The sensor in the gas pedal (the throttle control sensor) notices not only how far you press the pedal but also how quickly you pressed it. it will adjust the gear ratio of the transmission and the various aspects of the engine to quickly accelerate you.

What if you hit a slippery spot in the road while passing the previously mentioned Buick? The Computer is also measuring the speed of the wheels in relationship to one another. if it detects the drive wheels are spinning faster then the other wheels it will reduce the throttle to prevent you from continuing to slip. This is called advanced traction control.

As you come to a stop the cube's amazing CVT does something else really cool. it automatically initiates engine breaking. Every time you take your foot off the gas pedal it automatically adjusts the transmission gear ratio to cause the car to slow down. If you ever put a different exhaust on your cube you will hear this jake brake effect!

As you come to a complete stop the computer disengages the torque converter and you feel what some have discribed as a slight change in breaking force or a slight surge right before coming to a stop.

There is more. I have noticed that when starting to climb a hill the car automatically increases engine RPMs to hold a steady speed even though my foot has not pressed down any more on the gas pedal (this is without cruise control on). Also decending a hill, if I take my foot off the gas pedal the engine breaking comes into effect, the engine will rev a little to help hold your speed when going down hill.(you can increase this effect by pressint the overdrive off button on your gear selector)

So hopefully this answers some of your questions. What is really going on inside the computer is a complex dance of sensor readings, fuel map calculations, emission control adjustments, more sensors and actuators in the transmission. really. complex. stuff. :D
 

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Discussion Starter · #3 ·
Yes Cubit! This helps. One more question ...... Please forgive my ignorant terminologies, but is it possible for the computer to become "Temporarily confused"? ???
 

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Great write-p, Cubit! Very informative.

Thanks!




Cubists unite!
KandA
 
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