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Slight uncommanded acceleration

Slight uncommanded acceleration

P85D ~45K miles

About once a month or so for around 6 months I've detected a slight uncommanded vehicle acceleration that lasts less than a second. It's over before I can move my foot to the brake. It's an attention grabber for sure, somewhat akin to that moment when you turn the wheel on an icy road and the car doesn't turn.

I have no idea if it's associated with any sw update. Seems to happen most often when I slow and begin a turn on city streets. It's not sensitive to the regen setting. I don't believe it's driver induced.

A mystery...

NKYTA | 10/03/2019

TACC enabled?

DallasTG | 10/03/2019

Nope..

TeslaTap.com | 10/03/2019

Never seen something similar on my two Teslas. Something doesn't sound right do thing, but might be almost impossible for service to find such a rare intermittent. A couple of ideas:

TeslaTap.com | 10/03/2019

1) Try a reboot. Always surprising what it often fixes.

TeslaTap.com | 10/03/2019

2) If/When it occurs again, quickly press the voice button and say "Bug report - unexpected short acceleration". It may be necessary to do on 2 or 3 occurrences, and then have service look at the logs. Hopefully something will show up that can explain and fix it. Also note anything you can that might explain it occuring at that time

TeslaTap.com | 10/03/2019

for example, always on a right turn, or perhaps after hitting a pothole.

(had to split this post up to get through the anti-spam)

DallasTG | 10/03/2019

Great ideas will give it a shot!

Haggy | 10/03/2019

The only time I had anything like it, it was due to the Autopilot lever being inadvertently being pushed down when turning the steering wheel right after getting out of a parking space. If you have something like a heavy winter glove or an orange on your steering wheel or something else that could make something casually bump the lever without realizing it, then you'd feel a surge and it would end instantly when you instinctively tap the brake pedal. At the speeds it happened to me, it would have set it to 18 mph, which would have been a bit faster than I would have been going.

Beginning a turn is the circumstance that could cause what happened to me. It would also be theoretically possible to use the lever instead of the turn signal, but you'd be more likely to realize that.

PBEndo | 10/03/2019

The first time I drove loaner with AP1, this happened to me as I hit the TACC/AP lever when I intended to hit the turn signal as I was leaving the Tesla parking lot. Could it be that?

DallasTG | 10/03/2019

Hmmm...intriguing...it might be that, but I swear it ends before I can get to the brake.

In any event, I'll be more conscious of that and report back.

"Surge" is a the much better description.

Thanks all.

MilesMD88 | 10/03/2019

Never experienced this in 4 yrs, 2015 P85D. PBEndo has the best explanation which I’ve done. Gone for the turn signal, brain fade, pulled the TACC instead. Car attempts to accelerate to speed limit +9 which is my settings.

Chunky Jr. | 10/03/2019

Creep mode enabled?

Bumper | 11/03/2019

You are not nuts. I have felt the same in my MS a handful of times over the last year. It seems to happen just as I get my foot to the break. Like a little surge before I actually start really pushing on the pedal. As I push on the break it instantly stops. At no time have I felt in danger, but it for sure makes me wonder what is causing the glitch. When I read articles about folks that have their car accelerate through a wall or into a lake, it makes me wonder if just the right conditions will make this glitch go supernova. Thankfully the logs from those accidents frequently point to driver error (other accidents I just don't see any followup for so no idea).

PBEndo | 11/03/2019

@MilesMD88
It is easy to do as I have two Ses with the 2 different stalk configurations.

TeslaTap.com | 11/03/2019

@Bumper - All those cases of acceleration through walls, etc has been shown to be pedal misapplication - the owner pushes the accelerator thinking it is the brake pedal. Happens in all cars (ICE and EVs) every so often.

Toyota had a problem years ago with the floor mats trapping the accelerator, but that was a totally different issue.

TeslaTap.com | 11/03/2019

Also Tesla added a new feature last year "Obstacle-Aware Acceleration" to further reduce the likelihood of serious damage due to pedal misapplication at low speeds. I'm not aware of any other carmaker that offers such a feature. From the manual:

Obstacle-Aware Acceleration is designed to reduce the impact of a collision by reducing motor torque and in some cases applying the brakes, if Model S detects an object in its driving path. For example, Model S, while
parked in front of a closed garage door with the Drive gear engaged, detects that you have pressed hard on the accelerator pedal. Although Model S still accelerates and hits the garage door, the reduced torque may result in less damage.

More details in the manual.

hbwlau | 11/03/2019

2018 75D... I had had that happened a couple of times, while I at the service for an unrelated fix (air conditioning odor) last month, I told the service tech about the incidents, and I was told to make note of the incident at the precise date/time so they can review the log, I was also told that I could request a report from the car at the moment it happens, as TeslaTap suggested, I have not had that happened since though.

DallasTG | 13/03/2019

Update - it happened again 2 days ago.
City street slowing from 40 to a red light. No turning, left hand on wheel.
At around 20 mph right front wheel went into small pot hole.
Noticed it about time wheel exited pot hole.
Thanks to TeslaTap i recorded the bug immediately.

MilesMD88 | 13/03/2019

Avoid those potholes...haha
Let us know what the logs show, what you find out...thanks

jordanrichard | 15/03/2019

Bump, to get ahead of the spam

valrud | 15/03/2019

This is a repeat of my message of 12/2017.

"In spring of 2017, sudden acceleration happened to me while I was about to make a right turn. Luckily for me, I had enough time and space to press the brake pedal to avoid a collision.

I was not so lucky in June of 2017 when it happened to me again while I was about half way into a parking spot. The car jumped forward, and the damage was extensive.

In December of 2017, about four months after the car was repaired, I left my car in the San Diego Tesla shop for the annual service. A day after that, I received a call from Tesla, stating that their technician by accident ran the car into some obstacle. As a result, the front bumper of the car had to be replaced. Tesla did the repair in a matter of a few days."

kernel | 15/03/2019

Since there is mention of potholes, what I think is happening is that when the car is decelerating from regen and detects loss of traction (like if you fall into a pothole), regen seems to turn off momentarily until traction is regained. By doing so, there is a loss of deceleration, which feels like the car is accelerating briefly. Could that be it?

This happened to me recently too and it was enough to be alarming but not enough to actually be dangerous unless I was already tailgating way too closely.

DallasTG | 21/03/2019

Here is what the SC says:

Concern: Customer: states when slowing to a stop using regenerative braking the vehicle will sporadically lunge forward. Happens around 20mph.
Drive tech: Sharon is addressing this concern.
Corrections: Rear Drive Inverter General Diagnosis Conclusion: No Trouble Found
We were unable to duplicate this concern during the test drive.
Bug report was created on 3/11 @ 10:26:13. Looking at log data, traffic aware cruise control was set to 40MPH at 10:25:55 and then disabled at 10:26:01. This occurred while slowing to a stop and would explain the sudden acceleration as the set speed was noticeably higher than the speed the customer was traveling at when cruise was activated. The brake pedal switch state was set to "on" (Very sensitive switch) at the exact same time the cruise was enabled. That explain why it seems that the acceleration only occurs for a very short amount of time.

For the record I dont agree with that, but how can I argue with “the logs”…( I cant believe i would have the TACC engaged for 6 sec w/o realizing it)

I am not sure about the pothole/regen theory because it has happened several times on smooth pavement.

The only thing I am sure about is I’m buying the extended warranty....

Bighorn | 21/03/2019

Potholes can kick in ABS and make the braking feel briefly ineffectual on any car.

DallasTG | 22/03/2019

Nah this is a surge prior to braking..

Its there i know it

Stiction | 30/03/2019

I vote for traction control / abs.

I have a place where I drive up and over a hump, that also has train tracks at the top. . The traction control goes nuts, as the car is slightly unloaded from the hump, when I hit the tracks. Always gets me (and my passengers)
attention 8)