Brief torque loss during acceleration, a potential life-threatening event.

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rduclos

Member
Joined
Jul 8, 2017
Messages
10
Location
Nova Scotia, Canada
While similar events were described four years ago at http://www.mynissanleaf.com/viewtopic.php?f=30&t=18849&start=10 , my recent experiences have seriously upset my faith in the safety of EVs. I have owned and driven a 2014 Leaf 39000 Km over nearly four years, during which its quick and reliable acceleration had given me confidence in performing certain maneuvers, such as quickly merging into a traffic stream, or turning left through a gap in opposing traffic. Now I am experiencing occasional random total loss of torque during rapid acceleration, occurring usually one or two seconds after applying the increased power and lasting about a second, and sometimes repeating, then resuming full normal acceleration. I normally drive in Eco mode and often also in B mode. I live in eastern Canada with temperatures near freezing.

This is, as I said, occasional and random, and is hard to replicate. A dealer might never encounter it, so I am starting to take it seriously enough to try to analyse the circumstances when it does occur. I am also starting to drive more conservatively when in traffic (sort of spoils some of the fun of driving an EV).

Edit on Sun Feb 24, 2019 2:41 am:
Two months and two thousand kilometers later on the same car and driver this has not happened again!
So why it happened (about five times) last December is still a mystery. The last time was particularly bad as it occurred twice during the same acceleration while moving into a traffic stream ahead of another vehicle --- very upsetting at the time and leading me to post this notice the same day. I continue to drive more cautiously in traffic as a result.
 
It's possible it's normal and that it's traction control and/or stability control cutting power when it detects wheel slippage. What tires are you running? Are the front tires nearly worn?

You say "rapid acceleration" and "full normal acceleration" and "eastern Canada with temperatures near freezing." Also, you mention Eco. The responsive of the go pedal is really sluggish feeling for much of the travel in Eco (I almost never use it) and then perhaps you're making a sudden sharp increase when floor it or nearly floor it.

If it happens only on wet road or road that's snowy or slushy under hard acceleration, that's probably your problem. Do you have other FWD cars w/non-snow tires and with traction control or stability control?

Remember that on FWD cars, when you accelerate, the car squats and weight is transferred to the rear wheels, which provide no propulsion. And, weight is coming off the driven front wheels so there's less downforce on the fronts and more potential to lose traction and have the front wheels break loose.
 
rduclos,
Understand your concern 100%. That would be very unsettling if the acceleration wasn’t there when you expected and needed it.

Traction control could be part of the issue. (As cwerdna mentioned.) I remember (vaguely) that my 2002 Prius had an issue similar, but I think it was related to the breaking suddenly wouldn’t work over certain bumpy road conditions. Toyota had to replace the electronic components that sensed the road conditions. (Sorry at the moment can’t recall exact name of components).

Another possibility is the extreme cold temperatures (and aging) affecting the connections of the electrical components. Have dealer check all the connection. Also maybe the component controlling the acceleration needs to be replaced.

Besides contacting the Dealer I would also call customer service to see if there is any technical bulliten related to this kind of condition.

Because this is definitely a safety concern be sure to get resolved as soon as possible!
 
cwerdna said:
It's possible it's normal and that it's traction control and/or stability control cutting power when it detects wheel slippage. What tires are you running? Are the front tires nearly worn?

You say "rapid acceleration" and "full normal acceleration" and "eastern Canada with temperatures near freezing." Also, you mention Eco. The responsive of the go pedal is really sluggish feeling for much of the travel in Eco (I almost never use it) and then perhaps you're making a sudden sharp increase when floor it or nearly floor it.

If it happens only on wet road or road that's snowy or slushy under hard acceleration, that's probably your problem. Do you have other FWD cars w/non-snow tires and with traction control or stability control?

Remember that on FWD cars, when you accelerate, the car squats and weight is transferred to the rear wheels, which provide no propulsion. And, weight is coming off the driven front wheels so there's less downforce on the fronts and more potential to lose traction and have the front wheels break loose.

Another thing that can trigger traction-control is having differently-sized tires between front and back. I replaced 2 tires (due to puncture) on our 2012 and even though they were the same specs, the difference in diameter between the new and worn tires was enough to cause the car to hunker down, especially around turns. Dealt with it temporarily by swapping front/rear. I forget which tires ended up where.
 
Nubo said:
Another thing that can trigger traction-control is having differently-sized tires between front and back. I replaced 2 tires (due to puncture) on our 2012 and even though they were the same specs, the difference in diameter between the new and worn tires was enough to cause the car to hunker down, especially around turns. Dealt with it temporarily by swapping front/rear. I forget which tires ended up where.
I ran tires that had a larger diameter than stock for a while (235/50R17). What I found was that the size of the rears didn't matter. But having front tires with a larger diameter than stock really confused the traction control system. For the most part, there was no issue. But for whatever reason, taking a sweeping bend at around 40 mph would cause the traction control to kick in like crazy. I'd lose all forward momentum and slow down as the traction control kept pumping the brakes. It was very disconcerting.

rduclos, if you've installed tires with a different diameter as well, and you suspect that this might be what you're experiencing, then disable traction control. That "solved" the problem for me, at least until I wore out those front tires and replaced them with a smaller diameter tire.

Even when I replaced them, I went a little larger diameter than the 16" OEM tires (but should have been the same as the 17" OEM tires that Leafs came with a few years later, 215/50R17). And even with those tires, I had a problem when I kept the air pressure in the 40s. At that point, lowering the air pressure to 30-35 prevented the issue from happening. So that's another thought - even if you have the OEM 17" wheels, make sure you don't have the air pressure too high. The traction control doesn't like the little bit of increase in tire diameter that the increased pressure causes. The traction control is unnecessarily finicky.
 
rduclos said:
While similar events were described four years ago at http://www.mynissanleaf.com/viewtopic.php?f=30&t=18849&start=10 , my recent experiences have seriously upset my faith in the safety of EVs. I have owned and driven a 2014 Leaf 39000 Km over four years, during which its quick and reliable acceleration had given me confidence in performing certain maneuvers, such as quickly merging into a traffic stream, or turning left through a gap in opposing traffic. Now I am experiencing occasional random total loss of torque during rapid acceleration, occurring usually one or two seconds after applying the increased power and lasting about a second, and sometimes repeating, then resuming full normal acceleration. I normally drive in Eco mode and often also in B mode. I live in eastern Canada with temperatures near freezing.

This is, as I said, occasional and random, and is hard to replicate. A dealer might never encounter it, so I am starting to take it seriously enough to try to analyse the circumstances when it does occur. I am also starting to drive more conservatively when in traffic (sort of spoils the fun of driving an EV).
The problem and link you referenced are from my posting a few years ago. Unfortunately I no longer have the car or the service paperwork describing the repair. The skinny on the malfunction is the power control system thinks the brakes are applied, thus blocking acceleration. I do remember it involved replacing an insanely expensive brake system module and some software updates.
 
If my memory doesn’t fail me, that module was north of $2k USD at the time. I do remember it was enough to convince me that I never want to own one of these outside of full warranty protection.
 
rogersleaf said:
If my memory doesn’t fail me, that module was north of $2k USD at the time. I do remember it was enough to convince me that I never want to own one of these outside of full warranty protection.

So not an EV specific issue then...
 
DaveinOlyWA said:
rogersleaf said:
If my memory doesn’t fail me, that module was north of $2k USD at the time. I do remember it was enough to convince me that I never want to own one of these outside of full warranty protection.

So not an EV specific issue then...
Not enough information was gathered at the time to determine if this module was specific to the LEAF, or common to other vehicles, or if Nissan was price gouging for the repair part (similar to the electric water pumps). Also not known is why the module failed, or how frequently this actually happens, or if the module is still being used in production. I do know the failure did not log any diagnostic codes, did not flash any ABS or traction control indicators (as suggested by others), and that their LEAF tech was directed by Nissan support to replace the module as if they knew of the problem.

The event was significant enough to make me think twice about buying off the lease. I called it Strike 1 at the time. Strike 2 was being turned away from getting a simple tire rotation 4 months later because their LEAF tech was on vacation. Strike 3 was the negative-equity financing with disappointing resale value. Came to the personal conclusion that this technology was too exotic, too dependent on dealer service, and thus affordability too shaky for the long term. Hope to have better luck the next time.
 
Thanks to all seven of you for monitoring this site and commenting on my post! Like you, I love my Leaf and regard it as near perfect for what I do, driving locally forty or fifty kilometers each day.

To cwerdna, Nubo, garsh and SageBrush, I don't think actual wheel slippage is involved, as the incidents took place on dry roads and I have the best Michelin winter tires with only twelve thousand Km logged on them, and correct 35-36 lb pressure. I might turn off Eco mode, though I normally never have a problem accelerating with it on.

To lkkms2, I think you may be right about temperature and aging, as the worst events happened with outside temp a few degrees below freezing and I don't recall any incidents during summer. The car has been driven through much colder weather in previous winters, however. I live more than 120 Km from the nearest Nissan dealer, which I can just reach in warm weather but would be difficult this time of year, so I will put off a dealer visit until summer, as the car still drives like new most of the time, and I will avoid rapid acceleration in traffic.

To DaveinOlyWA and garsh, I will monitor the VDC traction control as best I can during away-from-traffic tests, with it on and off. I didn't notice it during the very brief incident that led me to post my concerns, or earlier ones.

To rogersleaf, thanks for elaborating on your original post of 2015. I sure hope my Leaf doesn't have the same fault as yours did. Mine is owned, not leased, and hopefully still in warranty for this type of issue.
 
FWIW, if you truly believe there is a safety defect, you could report it to https://www.tc.gc.ca/eng/motorvehiclesafety/reporting-defects-motor-vehicles.html. If some repair is actually needed, might be better to do it after it's been resolved or an attempt has been made to resolve.

It won't give you any immediate satisfaction or may not result in any reimbursement, but could result in a recall.
 
Whatever you find out please update the original post and make a new post announcing the update. This will greatly enhance this site and reduce frustration
 
I don't understand how the original poster can definitively say that there is a model-wide safety issue with the car just because he has experienced a problem. He needs to take it to the distant Nissan dealer to look for problems and codes on the computer.

We should also not be encouraging him to report an unknown symptom to governmental offices about "defects"... I mean, just because any car might stall or stop does not mean that they are not "safe" (as a blanket statement).

What I think this boils down to is that people appear to have a love/hate relationship with their cars and are willing to pull the plug on their relationship with the vehicle if they have a problem.. I hope they are not like that in their relationships..
 
I have also experienced this in my 2011. It only happens while in eco mode. On a few different occasions from a stop I would need decent acceleration and would not get it. A bit scary but nothing that was not cured by shifting out of eco mode.

Have not had that experience in Drive. Acceleration has always been fine in Drive.
 
rogersleaf said:
rduclos said:
While similar events were described four years ago at http://www.mynissanleaf.com/viewtopic.php?f=30&t=18849&start=10 , my recent experiences have seriously upset my faith in the safety of EVs. ... I am experiencing occasional random total loss of torque during rapid acceleration
The problem and link you referenced are from my posting a few years ago. Unfortunately I no longer have the car or the service paperwork describing the repair. The skinny on the malfunction is the power control system thinks the brakes are applied, thus blocking acceleration. I do remember it involved replacing an insanely expensive brake system module and some software updates.

Roger, in your post from 2015:
http://www.mynissanleaf.com/viewtopic.php?f=30&t=18849&start=10#p421769
...you mention an ABS module. I suspect that means this:
https://www.ebay.com/itm/2011-2012-2013-Nissan-LEAF-ABS-Control-Unit-Module-47660-3NA0A/112601854783?epid=516817297&hash=item1a3797f33f:g:qYEAAOSwwVBblN5u
...about $150 used.

Other things that have been suggested:
- try pulling up on the brake pedal. If that ends the slow-motion start, then maybe the pedal is not coming all the way up by itself (per Arnis)
- try driving with traction control disabled (see http://www.mynissanleaf.com/viewtopic.php?f=38&t=24738 )
- One person said driving without ECO fixed something possibly similar (but may have just been referring to the strange way the accelerator responds with ECO)
 
powersurge said:
I don't understand how the original poster can definitively say that there is a model-wide safety issue with the car just because he has experienced a problem.
I don't think he ever said that nor is it EVER required that there be a "model-wide safety issue" to exist with a car in order to report a safety defect to a regulatory agency. Even when recalls happen, in many cases, not all vehicles are affected.

These example recalls affected a small portion of the vehicle population:
https://www.ft.com/content/347f7b7e-87d9-11e5-9f8c-a8d619fa707c#axzz4BXHp5RVS affected one vehicle.
https://transportevolved.com/2015/07/20/smallest-recall-ever-2015-chevrolet-volt-involved-in-ten-car-steering-recall/ affected 11 vehicles, 1 of them a Volt
https://www.autoblog.com/2013/12/12/chrysler-200-avenger-compass-patriot-engine-recall/ affected 522 units
https://www.cnet.com/roadshow/news/ford-issues-three-recalls-two-of-which-cover-fewer-than-five-cars/ "Ford issues three recalls, two of which cover fewer than five cars"

My 06 Prius was recalled for a potential steering shaft problem. However, after inspection, it was not deemed affected.

Please look at pages 3 and 4 of https://static.nhtsa.gov/odi/rcl/2012/RCDNN-12V537-8546.pdf. Can you imagine if nobody reported the issues and it was just blown off? The NHSTA campaign id is 12V537000, if you want to do further digging at https://www.nhtsa.gov/vehicle/2006/TOYOTA/PRIUS/4%252520DR/FWD#recalls. You can look under associated documents for each recall for sometimes interesting PDFs.
powersurge said:
We should also not be encouraging him to report an unknown symptom to governmental offices about "defects"... I mean, just because any car might stall or stop does not mean that they are not "safe" (as a blanket statement).
I agree that in the case, since the vehicle hasn't been totalled in an accident yet, more can be done to investigate, attempt to repro and attempt to repair, if needed. This is why I wrote what I did.

As for the last part, if a car loses propulsion barring user error (e.g. running out of charge or fuel, incorrect operation of shifter or accelerator), those have become recalls. Google for name_of_automaker_here recalls stalling or name_of_automaker_here recalls may stop. Probably hundreds of millions of vehicles have been recalled worldwide for "stalling", for various reasons.
 
by downeykp » Thu Jan 03, 2019 1:55 pm

I have also experienced this in my 2011. It only happens while in eco mode. On a few different occasions from a stop I would need decent acceleration and would not get it. A bit scary but nothing that was not cured by shifting out of eco mode.

Have not had that experience in Drive. Acceleration has always been fine in Drive.

That is very noteworthy, I will keep that in mind. Perhaps Eco is not intended for emergency-type accelerations.

I continue to drive my Leaf daily as before, and have not experienced any repeat of the behavior that led me to start this thread, even while still driving in Eco mode.

I think I over-dramatized the title of this thread with the "life-threatening" wording, but I don't think I can change that now (would mess up all the replies, unless the site programming can compensate for that).
 
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