Stuck Throttle?

[lincomatic]

I don't want to get people too alarmed, because I wasn't in the car to observe what happened, but my wife had a big scare today. She was accelerating onto the freeway and then had to suddenly slow down due to stopped traffic. She hit the brake, slowed to a crawl, and when she released the pressure on the brake pedal, the car accelerated like the throttle was being depressed. She hit the brake again, slowed almost to a stop, and when she let up, it again lurched forwards. Finally, she pressed the brake pedal very hard. This time, the ABS kicked in, and as it was stopping, the front of the car dived... this really sounds like braking under power. The car was back to normal after she stopped and let off the brake this time. She insists that she didn't accidentally hit the accelerator, nor was there anything jamming the pedal.

Has anyone else experienced this? I'm wondering if I should take it in to the dealer or just chalk it up as a fluke.

 

[Boomer23]

I'd be at the dealer's first thing tomorrow if that happened to my wife. Or she'd know the reason why!!! :shock:

 

[GeekEV]

Wow, that's weird. It sure couldn't hurt to have the dealer pull some diagnostics off the computer. I would imagine the sooner the better so the don't get overwritten or erased! I've sure never had that happen. The worst that happens to me is occasional inexplicably grabby brakes at low speed - there was another thread about that somewhere...

 

[lincomatic]

I'd be at the dealer's first thing tomorrow if that happened to my wife. Or she'd know the reason why!!! :shock:

You're right. After posting last night, I decided to have her leave the car with me today. Hopefully, the dealer can fit in some time to try running some diagnostics, but I really wonder how they're going to figure anything out.

It was actually pretty surprising how calm my wife's reaction was about the incident. She said it was scary ... almost slammed into the car in front of her. Yet, she went on and drove it to a meeting before coming home, and had originally planned to take it to work again today.

 

[lincomatic]

OK, I took it to the dealer this morning. As I expected, it didn't throw any fault codes. After it came up clean on the diagnostics, they drove the car on the freeway testing it, enough to burn off 2 bars of charge, and weren't able to reproduce the problem. They also called Nissan, and the reply was that they hadn't received an reports of similar incidents. Someone from Nissan is supposed to call me and follow up.

I know the knee jerk diagnosis is that somehow my wife had her foot on both the accelerator and the brake, but she adamantly rules out that possibility. I looked at the car, and there's no way the floor mat could have gotten caught on the pedal. Also, the relative positions of the brake & accelerator pedals is such that it's not easy to depress them together unintenionally.

I *hope* it was just a fluke that won't happen again. We love our Leaf, and I'm not trying to be a rabble rouser about the car. In any case, I've instructed her to shift to reverse (which causes the car to beep and go into Neutral when it's in motion) if the car ever accelerates uncontrollably again ... AFAIK, this is the fastest way to get the car to instantly cut the power to the wheels while leaving all the other systems powered up. If someone has a better way to stop unintended acceleration let me know. Trying to shift to Neutral is no good, because you have to hold the shift lever in Neutral for several precious seconds before it switches to Neutral. I once tried hitting the power button while the car was moving slowly, and that wasn't a good idea, because the car suddenly stopped an engaged the parking pawl even though it was still in motion.

 

[palmermd]

I suspect this was an ABS problem. Pure speculation on my part, but there are other reports here on the forum if you search regarding ABS behaving oddly when in an emergency situation and going on and off brakes.

I suspect what she thought was acceleration was actually coasting. If you have ever driven an electric car that had zero regen it is a strange feeling. The first time you let off the accelerator, you feel as if you are accelerating because you are so accustomed to a car decelerating when off accelerator. You quickly get used to it, but the Leaf has regen off throttle and if it ever did not you might think it was accelerating. If she hit the brakes and then let off and the car gave no regen nor power it might feel like it was accelerating.

I'm glad everyone was ok. I hope this is the last we have to hear about unintended acceleration.

 

[DarkStar]

I suspect what she thought was acceleration was actually coasting.

This is my first thought as well. Lifting off the accelerator from an almost full battery in the EV has a completely different feel from an ICE.

 

[Herm]

Step on the brakes with both feet if you have to, and hold the power button down until it shuts off.. and so be it if the parking pawl engages with the car still in motion, better than a crash.

 

[smkettner]

Since she actually stopped the car, I believe the story.
The rest that have runaway acceleration and cannot stop are total BS.

Keep us posted. It could have been a perception of speed issue.

BTW she does not drive with two feet does she?

 

[EVDRIVER]

I seriously doubt the car computer made it accelerate on it's own. Likely a perception issue.

 

[lincomatic]

No, she doesn't drive with two feet.
The car still had regen because the SOC was about 50% at the time.
Yes, it's a good point that coasting could possibly interpreted as acceleration.
I wish I'd been in the car when it happened, because I could easily have verified if that was the case or not.

The Nissan Consumer Affairs rep gave me a call a little while ago. The guy at first said there was another incident, but then
retracted that statement, and said the other incident was an ABS issue.

I'm willing to give the car the benefit of the doubt. It's good to know that the brakes were good enough to stop it.

But ever since reading about the various unintended acceleration incidents w/ Toyota, I've been careful to work out methods of controlling
my cars in the unlikely even that such an incident would occur. I discussed how to cut the power in the car w/ the rep, and he said to rapidly
push the start button 3x. However, not only is this hard to do in a panic situation, but it turns the car off completely, which I suppose means you
lose both brake boost and power steering. So far, I'm going to stick w/ my idea of shifting to reverse to get it into neutral instantly, since it keeps
the steering & brakes powered up. The downside is if you're really stopped when you do it, the car really will go into reverse, so it should only be
done when the car is in motion.
[STANDARD DISCLAIMERS: DON'T AS I DESCRIBED ABOVE, I'M JUST SAYING WHAT I WOULD DO, DO IT AT YOUR OWN RISK BLAH BLAH BLAH]

 

[RickS]

You know I've noticed when I wear sandals it has a tendency to get stuck under one pedal or the other. I've not really had a problem with this with any other vehicle, but it's definitely not the cars fault.

 

[EVDrive]

I think the break and accelerator are a bit too close. I have hit the breaks in a similar situation and when I let off the breaks, lurched forward because the edge of my foot was unintentionally on the accelerator. Its actually easy to make this mistake in an emergency stop situation. I've done it three times.

 

[lkkms2]

Suggest your wife to drive in ECO mode. I normally drive in ECO mode, but once in a while forget and it feels like I am flying down the street. Especially when I first start in the morning and the batteries are charged up.

 

[bradleygibson]

This issue was on my mind (the Toyotas) when I picked up our Leaf.

If you ever need to kill the engine, the dealer told me either hold the power button down or press it three times.

I won't venture a guess as to what happened, as I wasn't a witness to it, but let's hope it was a perception issue.

I am surprised the cars don't have logs that the dealer can review. The logs would be able to indicate what the car thought the inputs were (throttle, brake, steering) and what it was actually doing (velocity).

Surprising they don't have logs...

Thank you for sharing,
Brad

 

[RickS]

From my understanding dealers typically can't pull data logs for privacy concerns. This information typically exists, but they will only have maybe two laptops in existence in the country which can pull this type of information and it requires a very high up person to have access to it.

For example I remember reading a press release about Toyota stating that they had two laptops which could pull vehicle crash data which would have this type of accelerator and brake pedal levels recorded. Also I know the normal Toyota scan tools dealers have can hard reset the vehicle immobilizers (if you loose all your keys) but only the shops master technician can access this feature and in talking to one he told me that he has to put in his social security number every time they do this so everything is traceable and tracked, basically to prevent vehicle theft.

So yeah, that information is not something you'd likely just be able to get. Admittedly I'm not that familiar with Nissan yet, but I suspect those procedures are more or less similar across the board.

 

[bradleygibson]

Weird, because if I felt my car was accelerating on its own, I'd give them permission to pull my personal data (would want to insist on it) before something horrific happened.

In any case I tested both the hold the button down for 3 seconds technique, and the triple press technique tonight on a quiet side road. Both killed the car dead, but the triple press is the quicker method of the two. Beware, you lose power steering, etc. so be safe if you choose to try this out.

-Brad

 

[myleaf]

Hi Everyone,

I have been noticing a similar effect while slowing to a stop at a traffic light. To me it seems there is a transistion following when the regenerative breaking is released. After which only the mechanical breaking is working. It gives a sensation of acceleration. Initially when I felt this effect, I probably applied additional brake pedal force, which cause a subsequent abrupt stop.
Still haven't gotten use to this yet, but I am not surprised by the sensation.

Does anyone notice a similar effect ??

 

[lincomatic]

Update...
I'm impressed with how Nissan really took this issue seriously, and are on top of things. The afternoon that I took it to the dealer, after the Consumer Affairs guy called, one of their engineers called me, too. He said if I hadn't taken the car home already, he would have asked the dealer to hold on the to car for a couple of days. He said he saw this thread on MNL, and also got the report from the dealer, so he knew it was the same guy. So if you have suggestions/rants about the Leaf, it's nice to know that they're being heard by Nissan, even if they don't respond via the forum. I also got a message from Nissan NA in TN, but haven't been able to touch base w/ them yet.

Also, I discussed the incident again with my wife, and she said the car wasn't just rolling when she let off the brake, that it lunged forwards. Also, it was on a flat road, not downhill. Anyway, I haven't experienced it myself, and it hasn't happened again since.

 

[lincomatic]

I forgot to mention something interesting the engineer told me. He said the car has a data logger that collects data only when triggered by a DTC. The dealer doesn't have access to the data, only Nissan can get to it. My car had no DTC's, so no data.