M3 suddenly slowed down while in Navigate on AP mode

M3 suddenly slowed down while in Navigate on AP mode

A couple of days ago, I was driving around 70 mph on I-280, in broad daylight with NAP on. The road was completely clear in front of me. Suddenly my M3 slowed down for several seconds as if I had just hit the brake. Then it resumed the set speed. Has anyone experienced a similar problem?

There was one car behind me (in my lane). I hope brake checking is not a feature included in the EAP software.

I have the latest software 2019.5.3 e31b992.

Hal Fisher | March 10, 2019

look at the top speed rated for the road your on when it does this. The speed may suddenly say 45 mph because it thinks it’s on the side road. I drive in the next lane over to prevent this. Report that spot to tesla, maybe they can fix it remotely.

Magic 8 Ball | March 10, 2019

It happened to me on 280 near 92.

Bighorn | March 10, 2019

Any overpasses or signage that could have been mistaken for an obstacle? Driving by an exit in the right lane sometimes will slow to what I presume is ramp speed.

Magic 8 Ball | March 10, 2019

In my case I was going under very high up overpasses and been through there before without incident. It is possible surrounding traffic may have played a role but there was nothing directly in front of me nor looking like they were going to encroach my lane. I was just in EAP not Nav On.

tung1900 | March 10, 2019

Check out YouTube on that,
It says cloud shadow can do that.

M3phan | March 10, 2019

I’ve never heard of nor experienced cloud shadow causing that. The other things mentioned above, yes. | March 10, 2019

Mine consistently does this on I-125 in Denver North bound at bridge for the light rail crossing at Arapahoe Station, very annoying

gmkellogg | March 10, 2019

I've had this happen to me at night. When I checked, the set speed had changed from 70 to 53 and I'm 100% sure I didn't hit the scroll wheel.

nhunguyen | March 10, 2019

It happened to me on 101 passing Tully about going toward the 280 overpass. Twice!!
Hope the car sending info back to Tesla.

Carl Thompson | March 10, 2019

The car literally is frightened of shadows. However, my previous commute car (a BMW) was much worse and panic-braked much more often.

Magic 8 Ball | March 10, 2019

What I experienced was far from a panic brake, it was more like hard regen. It was an automatic reflex to stomp on the accelerator to override and since I pull over when people tailgate me it was never an issue.

windfall2 | March 10, 2019

It happened to me, I was passing an exit. I will take Hal’s suggestion if it happens again

Rbnaidu | March 10, 2019

i have had the same happen to me on 880S a few times since my last firmware update. Never had this issue prior to the update. I suspect it has something to do with the firmware. Hopefully future release fixes this problem. I have reduced its usage in fear someone rear ends my car.

2pwr10 | March 10, 2019

yep, it happened to me going 70 on 65 on 680N (with 4 lanes), was in the second lane from left. I can remember a yellow car in my right lane speeding ahead in its lane, left lane was empty, yeah it was cloudy, luckily the guy behind me was a bit far. My reflexive reaction was look in the rear view mirror and hit the accelerator simultaneously :) my heart might have skipped a beat. though nothing happened, I guess its a better driving experience in the night. except the other night it went over a shiny metal plate (atleast a foot high and 5 feet wide) lying right in my lane at 2:30 am with rain drizzling (dont ask, late night airport pickup, flight was just 5hrs late), did not have enough time to react to the obstacle to disengage AP, give indicator and change lane, I just grabbed the steering tight and held my breath, luckily it seemed like an aluminium frame, just scratched paint under the front fender (just ordered paint fix from Tesla). My Mom sitting next to me let out a yelp and closed her eyes and my dad in the rear seat was sound asleep and did not feel a thing until we told him when we reached home.

RedPillSucks | March 11, 2019

People should file a bug report when this occurs, so Tesla will pay more attention to this and hopefully fix the issue.

gcklo | March 11, 2019

2019.5.4 or before has Autopilot bugs.

I just got 2019.5.15 yesterday and it seems like the bugs have been fixed.

M3NOICE | March 11, 2019

@gcklo Good to hear that.
I found 2019.5.4 while on TACC very "moody" with short, sudden slowdowns without any particular reason. I am still using it daily, but definitely looking forward to the next rev.

ccash | March 11, 2019

I agree with you M3NOICE, "moody" is a good word for it. Will update to 5.15 tonight.

As a noob, should I find it odd that we're descending in version numbers?

Rt002k | March 11, 2019

If there is a merging lane next to you, or two lanes over, I have found that it will latch on to the car in the lane and slow down expecting it to merge. Easily notice don the screen - the car you are tracking is darker during day mode, lighter during night mode, and you can see it switch this to the car in the lane next to you. It can be a bit jarring when it's the lane two over that's merging (and stupid in my opinion). It's not a bad feature but is not implemented very well. It will do this even if there is plenty of time for you to get ahead of that person if you continue your current speed.

I have experienced this several times - but never the sudden speed limit change, and haven't had the phantom shadow issue since about week 1 with the car (July).

LeePA | March 11, 2019

I updated my software to version 2019.5.15 yesterday and the problem occurred again today: on I-280 going north (from Palo Alto to San Francisco) *** just before I reached the Sand Hill Road overpass ***. I was on lane 2 of a 4-lane highway going about 70 mph. Since the problem happened before, this time I paid attention to the surroundings when it occurred. The sky was clear, no car ahead on my lane or the adjacent lanes. There was a sharp shadow of the overpass on 280! If I have to guess, this shadow might have been misinterpreted by the AP software.

I've had just 4K miles on the car and the problem occurred only twice (both incidents within the last few days).
How can I report this specific incident to Tesla so they can review the situation? Preferably not immediately after the incident because I'd rather pay attention to driving than filing a real-time bug report.