Acceleration pedal calibration problems ?

[DaveinOlyWA]

The sudden 90 mph just shows that instantaneous wheel speed, even a small spin/slip, gets translated into a visible mph.

yes it does and in a very low traction environment, i think it backs up Turbo's assessment that the throttle response does not correlate well with pedal position beyond a very low threshold

granted this was a while ago, but when i hit that 80-90 mark, i might have been pushing the pedal 3 inches at most. was much less than half way.

when it was pulsing into the 30 mph range, i might have been pushing it an inch at most.

 

[Coffee_Slurry]

Ever since Turbo described it, I can't stop playing with it!

If I launch from a green-light with full-press, then let off slowly, it's all kinds of weird. Full motor power until just the very.. very.. last bit of lift-off.

That can't be right, but it's not frightful either.
Interesting, and 100% reproducible.

 

[turbo2ltr]

I noticed the other day that you don't even have to press it fully right off the bat. It seems just an abrupt change in throttle from a stop will cause it. Like press 30-40% from a stop and hold it.

 

[evnow]

Acceleration pedal is not linear, though what turbo is describing is different. Infact regen on acceleration pedal means it can't be linear.

The car is always responsing to whether you are pressing the pedal or lifting the pressure off of the pedal. For eg. when you press a little - let us say 1" - you get a bit of acceleration. But when lifting off the pressure on the pedal with the pedal now at 1" - you may get regen i.e. deceleration ! So, the linear position of the pedal does not determine the acceleration completely - lot of other things go into determining the power supplied.

 

[johnr]

What has been described in this thread is my experience as well. Exactly as Turbo and Groundloop have described. I think this behavior is by design, as the response is thereby tailored for optimal resolution at any speed. When accelerating, it gradually increases the power until you back off. I've noticed when I back off after accelerating up to speed, it feels almost like a deceleration. That's just a side effect of this. If it did not have this feature, the pedal response would be linear from 0% = 0mph to 100% = 90mph, and the car would be much more difficult to control. As someone else has said, this also makes it feel more like a traditional engine vehicle which has a more narrow speed range at each gearing range. So, I think what is being described is just a side-effect, or even an advantage, of this nonlinear control. For the most part, I like it.

 

[DaveEV]

If it did not have this feature, the pedal response would be linear from 0% = 0mph to 100% = 90mph, and the car would be much more difficult to control.

I disagree - what one expects is that the pedal position will more or less result in a linear change in power output. 0% = 0 kW, 50% = 40 kW, 100% = 80 kW. A regular car pretty much behaves this way (though it depends on engine RPM and transmission gear). If the pedal behaved more linearly - we wouldn't be having this discussion right now.

 

[turbo2ltr]

I disagree - what one expects is that the pedal position will more or less result in a linear change in power output. 0% = 0 kW, 50% = 40 kW, 100% = 80 kW. A regular car pretty much behaves this way (though it depends on engine RPM and transmission gear). If the pedal behaved more linearly - we wouldn't be having this discussion right now.

100% agreed. In general, the pedal isn't tied to speed, it's tied to torque, which combined with other variables like wind resistance and other losses, will ultimately dictate your end speed. This is true in an ICE or EV. But the leaf in this particular failure mode is not acting that way.

 

[johnr]

Pedal isn't tied to speed, it's tied to torque, which combined with other variables like wind resistance and other losses, will ultimately dictate your end speed. This is true in an ICE or EV.

I'm surprised to hear you say this, as we have both experienced the software-skewed control of the pedal - where you accelerate, then you ease up a little, then pressing again to the same position results in a different acceleration rate than expected. Again, I'm not saying this is a bad thing - but my point is that it is not simply tied to speed or even torque. It's clear to me that there must be a software-imposed hysteresis at play here.

 

[turbo2ltr]

Pedal isn't tied to speed, it's tied to torque, which combined with other variables like wind resistance and other losses, will ultimately dictate your end speed. This is true in an ICE or EV.

I'm surprised to hear you say this, as we have both experienced the software-skewed control of the pedal - where you accelerate, then you ease up a little, then pressing again to the same position results in a different acceleration rate than expected. Again, I'm not saying this is a bad thing - but my point is that it is not simply tied to speed or even torque. It's clear to me that there must be a software-imposed hysteresis at play here.

Sorry, I was talking about expected behavior in both the EV and ICE, not actual behavior in the leaf. Edited for clarity.

 

[DaveinOlyWA]

so can say postulate that motor response to pedal is mimicking a variable transmission response in regular car? that does seem plausible but at the same time, it seems to be mimicking automatic transmissions of the 80's and not the one's of the 21st century

 

[palmermd]

I noticed the other day that you don't even have to press it fully right off the bat. It seems just an abrupt change in throttle from a stop will cause it. Like press 30-40% from a stop and hold it.

This is what I experienced as well. I never noticed it when pressing hard on the pedal because I expect a lot of power when you press down further. What caught me by surprise was when the car did it when only pressing 20% or so on the pedal. Like I explained in the other thread. http://www.mynissanleaf.com/viewtopic.php?p=176502#p176502" onclick="window.open(this.href);return false; If you press down quickly from a stop you get power to ramp fully to 80kW. If you press more slowly to the same 20% you get 5kW. Once the car is rolling you can press to the same place as quickly or slowly as you like and you will always get the 5kW output. It is only when stopped that when you quickly press to the same 20% that the motor ramps to 80kW.

 

[garygid]

Perhaps this the "Drag Racer" feature?

However, for somebody like my wife, this "computer-generated" strong acceleration would be a panic-causing event.

Since the same effect can be achieved by "punching" the throttle all the way down, it seems totally unnecessary, and a safety issue, to have a 20% pedal position (from stop only) produce a full-power Drag-Race effect.

I call it a BUG, ...
until Nissan recognizes this "feature" and explicitly says that it is intentional.

Each time you experience this, you should call LEAF Customer Support and report it. After a thousand calls, if Nissan still ignors it, then time to report it to the National Traffic Safety Board.

(My Opions.)

 

[palmermd]

it is a bug, but not really a problem. When the car starts doing this, if you get scared, you let of the accelerator pedal and the car stops accelerating. No big deal. It is just a quirk in the code. Not worth reporting to Nissan.

 

[garygid]

After this BUG causes confusion and an accident or death, ...
only then take it seriously?

 

[palmermd]

If it eases your mind, then by all means go ahead and report it.

I'm comfortable that any normal person will not have an issue with this. Heck many cant replicate it when they try. Instinct is to pull your foot when it happens, and the event stops.

Have you tried replicating this quirk? Were you able to do it? How did you react?

 

[Nubo]

Perhaps this the "Drag Racer" feature?

However, for somebody like my wife, this "computer-generated" strong acceleration would be a panic-causing event.

Since the same effect can be achieved by "punching" the throttle all the way down, it seems totally unnecessary, and a safety issue, to have a 20% pedal position (from stop only) produce a full-power Drag-Race effect.

I call it a BUG, ...
until Nissan recognizes this "feature" and explicitly says that it is intentional.

Each time you experience this, you should call LEAF Customer Support and report it. After a thousand calls, if Nissan still ignors it, then time to report it to the National Traffic Safety Board.

(My Opions.)

From the sounds of it, it's definitely goes against the universal expectation of what a throttle does and whether or not someone would normally react to abort it, still represents a safety hazard, imo. It's like the computer is applying an exponential function. Not good.

 

[lpickup]

From the sounds of it, it's definitely goes against the universal expectation of what a throttle does and whether or not someone would normally react to abort it, still represents a safety hazard, imo. It's like the computer is applying an exponential function. Not good.

True, but my experience is that I had to try really hard to even get it to happen in the first place. It's just not instinctual to hold the pedal absolutely still for that long while you're accelerating. The LEAF has pretty good acceleration, but not so good that you don't have plenty of time (and instinct) to ease off on the pedal. If not for the fact that people were talking about it here I seriously doubt I would have ever even noticed this behavior.

 

[EVDRIVER]

My car has none of these bugs. Most are imagined and group think. One of my friends had a LEAF pedal bug until I proved to him it was perception not reality, he was convinced and the felt like a fool once he released his mind was tricking him. Too many people treat the LEAF like a lab rat under study and find issues that would otherwise be unknown to most. Like the car accelerating on its own. If this were remotely true every LEAF would be recalled before you could say HEPI.

 

[DaveEV]

My car has none of these bugs. Most are imagined and group think.

Just because you have not experienced it, does not mean it does not exist. turbo2ltr documented this behavior and provided evidence long, long ago in this post:

http://www.mynissanleaf.com/viewtopic.php?p=112560#p112560" onclick="window.open(this.href);return false;

I can't believe it's still up for debate!

 

[DaveinOlyWA]

My car has none of these bugs. Most are imagined and group think.

Just because you have not experienced it, does not mean it does not exist. turbo2ltr documented this behavior and provided evidence long, long ago in this post:

http://www.mynissanleaf.com/viewtopic.php?p=112560#p112560" onclick="window.open(this.href);return false;

I can't believe it's still up for debate!

i agree but the debate is not whether it exists as it has been reported by more than enough to consider this a valid event. now as to whether it warrants a fix? well, if it concerns anyone, then it should be addressed.

i tried to reproduce it and i "believe" i have. i fail to see the problem but its like anything else. "knowing" and "expecting" greatly influenced my decision that it is not an issue

but like the person who gets lost in an unfamiliar area, the unexpected needs to be more "predictable" and i believe this will cause an accident and be attributed to a perceived UIA