Odd throttle behavior

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turbo2ltr

Well-known member
Joined
Jul 31, 2010
Messages
1,376
Location
Phoenix, AZ
I've been hesitant to post this as I thought it was just my imagination, but I've proved it to myself so many times now, it must be real.

I have a heavy foot and I do not drive conservatively. If you do, then you would probably never run into this.

In normal drive mode from a stop, if you aggressively get on the throttle, then partially back off a couple seconds later, many times the car keeps pulling with excessive power output compared to the throttle position. When I feel this extra power, my test has been to note how far down I have the pedal by letting completely off (usually it's very little). Then I go to that same throttle position, and the power ("butt dyno" as well as the bubble meter) is significantly less. There is definitely something wacky. I might have to log some CAN data to capture it.

It only seems to happen when you aggressively get on the throttle from a stop or very slow roll.

I have never experienced this in Eco mode.

Anyone else?
 
Yes, I've observed it too and have a hypothesis as to what might be happening... I suspect that when you first apply a lot of throttle, you are requesting power more than the car can provide for whatever reason at that instant. When you subsequently back off the throttle, you are still requesting what the car is already providing, or perhaps still more than it can, and thus there is no real change in power. Just a theory on my part...

turbo2ltr said:
In normal drive mode from a stop, if you aggressively get on the throttle, then partially back off a couple seconds later, many times the car keeps pulling with excessive power output compared to the throttle position.
 
That doesn't sound terribly dangerous, but it does seem to fit under the general definition of "uncommanded acceleration". As such, I would guess that Nissan would want to investigate this lickity-split. People seem pretty darn litigious about such things, these days.
 
Naw, I don't think it is dangerous at all, in fact. I found it much more interesting that bothersome... I've seen similar behavior from some ICE vehicles with electronic throttles.

DaveNagy said:
That doesn't sound terribly dangerous, but it does seem to fit under the general definition of "uncommanded acceleration". As such, I would guess that Nissan would want to investigate this lickity-split. People seem pretty darn litigious about such things, these days.
 
Hello,
Mine does it as well. I think (opinion - not derived from empirical test data) in "Drive" mode the current curve programmed into the inverter is simulating an ICE experience so it ramps up the current to give the feeling of engine torque increasing as it revs up. So it is still ramping up as you are letting the E peddle up until it's up enough to limit the power. Not happening in "Eco" mode.

On Edit: I also THINK that part of it is because when you let up the throttle you are expecting it to back off and when it doesn't the experience is amplified. Example, when you step on the brakes and they don't work it actually feels like you are accelerating.
 
turbo2ltr said:
I've been hesitant to post this as I thought it was just my imagination, but I've proved it to myself so many times now, it must be real.

I have a heavy foot and I do not drive conservatively. If you do, then you would probably never run into this.

In normal drive mode from a stop, if you aggressively get on the throttle, then partially back off a couple seconds later, many times the car keeps pulling with excessive power output compared to the throttle position. When I feel this extra power, my test has been to note how far down I have the pedal by letting completely off (usually it's very little). Then I go to that same throttle position, and the power ("butt dyno" as well as the bubble meter) is significantly less. There is definitely something wacky. I might have to log some CAN data to capture it.

It only seems to happen when you aggressively get on the throttle from a stop or very slow roll.

I have never experienced this in Eco mode.

Anyone else?

Could be the vibration control system doing its job.

Read page 20, 3rd-5th paragraph:
"Electric drive motors provide outstanding torque response that is makedly superior to that of conventional gasoline and diesel engines...."
http://www.electricauto.org/resource/resmgr/media/nissan_leaf_sae_2_11.pdf
 
turbo2ltr said:
I've been hesitant to post this as I thought it was just my imagination, but I've proved it to myself so many times now, it must be real.

I have a heavy foot and I do not drive conservatively. If you do, then you would probably never run into this.

In normal drive mode from a stop, if you aggressively get on the throttle, then partially back off a couple seconds later, many times the car keeps pulling with excessive power output compared to the throttle position. When I feel this extra power, my test has been to note how far down I have the pedal by letting completely off (usually it's very little). Then I go to that same throttle position, and the power ("butt dyno" as well as the bubble meter) is significantly less. There is definitely something wacky. I might have to log some CAN data to capture it.

It only seems to happen when you aggressively get on the throttle from a stop or very slow roll.

I have never experienced this in Eco mode.

Anyone else?

Try to apply the brake pedal for a brief moment - gently -
This may be a feed back loop issue -

If it is and the effect goes away once you hit the brake pedal, then it is a "software" issue...

Ralph
 
turbo2ltr said:
In normal drive mode from a stop, if you aggressively get on the throttle, then partially back off a couple seconds later, many times the car keeps pulling with excessive power output compared to the throttle position. When I feel this extra power, my test has been to note how far down I have the pedal by letting completely off (usually it's very little). Then I go to that same throttle position, and the power ("butt dyno" as well as the bubble meter) is significantly less. There is definitely something wacky.

If Nissan uses a PID type motor control algorithm you may be experiencing integral windup. If it is windup the excessive acceleration would correct itself over time. You may not be able to tell however due to the ultimate speed limit.
 
Yes. It does seem to be a side effect of the fly-by-wire throttle software. IMHO it is not really dangerous put will raise an eyebrow the first couple times you experience it. You will be lifting from full throttle (maybe back to 70-80% throttle position) but the car will still be pulling 100% torque for a second or two while you are lifting. If you lift suddenly and completely the torque cuts out real fast as expected. It's the slow lift from full throttle that makes you go hummmm? Probably just needs a small software tweak.
 
I've noticed something like this a couple of times. Almost like the car is not delivering the same amount of power with the reapplication of the throttle. Or the car is delivering too much power on the initial application of the throttle. Either way. I'm not sure what to make of it, but I kinda like the extra power from takeoff and sorta dislike the way it feels when the throttle is backed off and then reapplied. So clearly the answer to me would be to stay on the throttle hard no matter what (unless it became dangerous to do so). :lol:
 
JimK said:
turbo2ltr said:
In normal drive mode from a stop, if you aggressively get on the throttle, then partially back off a couple seconds later, many times the car keeps pulling with excessive power output compared to the throttle position. When I feel this extra power, my test has been to note how far down I have the pedal by letting completely off (usually it's very little). Then I go to that same throttle position, and the power ("butt dyno" as well as the bubble meter) is significantly less. There is definitely something wacky.

If Nissan uses a PID type motor control algorithm you may be experiencing integral windup. If it is windup the excessive acceleration would correct itself over time. You may not be able to tell however due to the ultimate speed limit.

I guess you are referring to this thing: http://en.wikipedia.org/wiki/PID_controller

The problem is that it only occurs in this one defined stage not all over the spectrum of acceleration, so the PID controller has no way of “learning” what is wrong…
That is why I asked to “change” input devices – AKA the brake pedal – once triggered it will reset the original input – and for that session of driving the “hokus pokus” will disappear, until the next start / hard acceleration session is initiated.
A little trick to avoid this:
Foot of break – on to gas, then a very low pressure onto the go pedal and then actively increase your go “signal” this should avoid the “blind” spot that is currently programmed into the motor control software.
So please if you guys that have experienced this issue please “feedback” if hitting (lightly just for contact) the brake pedal indeed resolve the issue.
If it does then it needs to be addressed by Nissan – since it is a software issue (feedback loop)
 
Could be the vibration control system doing its job.

That is why I asked to “change” input devices – AKA the brake pedal – once triggered it will reset the original input – and for that session of driving the “hokus pokus” will disappear, until the next start / hard acceleration session is initiated.

Foot of break – on to gas, then a very low pressure onto the go pedal and then actively increase your go “signal” this should avoid the “blind” spot that is currently programmed into the motor control software.


Holy speculation batman. Where do you people come up with these things?
 
turbo2ltr said:
Could be the vibration control system doing its job.

That is why I asked to “change” input devices – AKA the brake pedal – once triggered it will reset the original input – and for that session of driving the “hokus pokus” will disappear, until the next start / hard acceleration session is initiated.

Foot of break – on to gas, then a very low pressure onto the go pedal and then actively increase your go “signal” this should avoid the “blind” spot that is currently programmed into the motor control software.


Holy speculation batman. Where do you people come up with these things?


This is what you do here, make stuff up. If you want to solve your problem get the clear throttle retraction protector, it's $24.95 from Nissan but is on back order until 4/21.
 
EVDRIVER said:
This is what you do here, make stuff up. If you want to solve your problem get the clear throttle retraction protector, it's $24.95 from Nissan but is on back order until 4/21.

Lol! :lol: :lol: :lol:
 
EVDRIVER said:
This is what you do here, make stuff up. If you want to solve your problem get the clear throttle retraction protector, it's $24.95 from Nissan but is on back order until 4/21.

You are better off with the black one, it wont show scuff marks as readily, but its also on backorder!
 
throttle response on gas car;

depress an inch, torque response = 10%
depress 2 " torque response = 20 %


throttle response on EV;

depress an inch; torque response= 100%
depress 2 " torque response = 100%

any questions?

this is also why i use eco all the time. it really makes a difference when trying to control speed under 40 mph
 
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