Phantom braking so bad I want to return my car

[Tha_Ape]

Yes - I’ve experienced the phantom braking and it sure scares the out of ya. But here is an interesting twist and not sure others have noticed this. I’d have AP engaged and set to 75mph in a 65mph zone. Traffic was all moving at 75mph or more. I crossed from a 65mph zone to a 55mph zone (everyone was still driving 75mph) and the AP braked aggressively to, yes, get the speed down to 55mph. Was a little surprised when this happened and it has happened more than once. Now I’m starting to wonder if some (and I do mean some) of these phantom braking issues are related to AP moving between speed zones.

I have radar and have had some PB experiences in the past, havent had any in about 6months. The ones I did have recently can be explained by EXACTLY what you mentioned above. The car thinks I'm off a highway so it limits speed to 5 over what it thinks the limit is. It took me a while to realize what was happening. I kept being told radar sees an overpass yadayadayada.... but I paid attention to the speedometer and indicated speedlimit in the car once and saw it drop when I went near the overpass (I think it thought I was on an off ramp or the road above). So that is no longer "PB" to me, its explained. Hopefully this latest map update remedies that.

I used to get PBs from trucks pulling up next to me which i think was the vision part of TACC over reacting, but I honestly cant remember the last time thats happened.

 

[ElectricAnt54]

Yes - I’ve experienced the phantom braking and it sure scares the out of ya. But here is an interesting twist and not sure others have noticed this. I’d have AP engaged and set to 75mph in a 65mph zone. Traffic was all moving at 75mph or more. I crossed from a 65mph zone to a 55mph zone (everyone was still driving 75mph) and the AP braked aggressively to, yes, get the speed down to 55mph. Was a little surprised when this happened and it has happened more than once. Now I’m starting to wonder if some (and I do mean some) of these phantom braking issues are related to AP moving between speed zones.

I have moved between speed zones (faster to slower) and autopilot did not slow down. I just used autopilot + autosteer to do most the driving over 700 miles & had no issues.
Perhaps people are pressing the detected speed icon by accident? That will slow down the car.

Model Y Owner's Manual | Tesla

Learn about Speed Assist and its specifications.

www.tesla.com

 

[Icehedgehog88]

I never touched the speed icon. It just does it randomly. BTW thanks for pointing me to the manual which confirms the weirdness of what’s going on.

 

[WhiteWi]

Car is smarter than you think Sleepydoc.

 

[WhiteWi]

It sees and trying to predict what happens all the time. That is why we see some random PB events.

 

[NYMY]

I do wish that it didn't presume that everyone walking on the side of the road was heII bent on jumping out in front of the car.

so true. and it drives along happily until it suddenly decides this is threat level 11 and must brake immediately

 

[sleepydoc]

Yes - I’ve experienced the phantom braking and it sure scares the out of ya. But here is an interesting twist and not sure others have noticed this. I’d have AP engaged and set to 75mph in a 65mph zone. Traffic was all moving at 75mph or more. I crossed from a 65mph zone to a 55mph zone (everyone was still driving 75mph) and the AP braked aggressively to, yes, get the speed down to 55mph. Was a little surprised when this happened and it has happened more than once. Now I’m starting to wonder if some (and I do mean some) of these phantom braking issues are related to AP moving between speed zones.

ve radar and have had some PB experiences in the past, havent had any in about 6months. The ones I did have recently can be explained by EXACTLY what you mentioned above. The car thinks I'm off a highway so it limits speed to 5 over what it thinks the limit is. It took me a while to realize what was happening. I kept being told radar sees an overpass yadayadayada.... but I paid attention to the speedometer and indicated speedlimit in the car once and saw it drop whe

This may explain some events. Others have postulated that areas where the car is on a road passing over or under another road with a different speed limit causes the system to get confused. Ultimately, they are still system failures. The job of adaptive cruise is to keep the car traveling at the correct speed limit, slowing down for cars or obstacles in its path. Period. You may be able to explain a PB event by a bridge, shadow, GPS confusion, etc, but what ever the reason, it's still a failure.

 

[sleepydoc]

Car is smarter than you think Sleepydoc.

Than why is it I can tell when it's wrong but it can't?

It sees and trying to predict what happens all the time. That is why we see some random PB events.

ah, but it's not that smart for exactly the reasons you state - it ties, gets it wrong and we see random PB events. i.e. it fails. If it was doing a better job than every other car on the road I'd forgive the mistakes. Heck, even if it was doing better than half the cars on the road it'd still be better than average. But it's not.

Edit: Did you just admit that PB is real????

 

[Tha_Ape]

This may explain some events. Others have postulated that areas where the car is on a road passing over or under another road with a different speed limit causes the system to get confused. Ultimately, they are still system failures. The job of adaptive cruise is to keep the car traveling at the correct speed limit, slowing down for cars or obstacles in its path. Period. You may be able to explain a PB event by a bridge, shadow, GPS confusion, etc, but what ever the reason, it's still a failure.

Agree its a failure, but seems like an easier one fix with maps/logic update other than some sort of vision algorithm in which fixing may affect something else. Updating maps is benign

 

[SalisburySam]

For me, v20.8 has reduced the number of DEFCON 1 panic-inducing PB events to almost never…only have had one since the update. Still getting the occasional and annoying DEFCON 4 events. If this trend continues my (disparaging) thoughts about Tesla’s software team could actually improve…not that they’re at all concerned about my opinion.

 

[MylerB]

PB used to be horrible with vision only cars, it was bad enough that I actually regretted purchasing my car... but it improved by a huge amount after the NHTSA investigation was started... now it is pretty comparable to the radar equipped cars unless you have FSD Beta... if you have FSD Beta it is still significantly more paranoid than regular AP with vision only or with radar.

I do wish that it didn't presume that everyone walking on the side of the road was heII bent on jumping out in front of the car.

Keith

So reassuring - thank you for this. The posts I found go back several months and indeed it seems to have been way worse a little while ago. Certainly seems to have died down compared to then.

 

[sleepydoc]

We drove from Minneapolis up to Grand Forks yesterday and had zero phantom braking events all the way to Fargo. I've never been able to drive this long without PB issues. Driving north from Fargo there was a section construction where it was reduced to a 2 lane road with orange construction posts dividing the lanes. In this section it would slow down randomly about every 1-2 miles. I don't spend a ton of time on interstates normally but AP/TACC appears to be much better than other roads, even if they are divided.

 

[pmont1]

May have to add another situation for PB. Has anyone had PB with blue mile marker signs in the median of an interstate? I had three moderate PB for these at night between Nashville and Knoxville on I-40. By the third one, I was able to correlate the PB to the signs. Thinking that the car confuses the Blue reflection of the mile markers with blue emergency lights.

 

[cmy4x4]

No trips planned for the near future, but anxious to get on the road and see if the latest update V2022.24 has any affect on PB!

 

[Dennisis]

In the middle of a 2.5K trip using AP a lot on 2022.24.6. Middle of the day, straight interstate with no one close cruising at 80 and all of a sudden we slow to 40 or so before I can hit the go pedal. Happened 3 times in similar conditions - frustrating. And for some reason it wants to move to the passing lane though no one is ahead for a mile or so, happened many times. Still room for improvements!!

 

[SalisburySam]

In the middle of a 2.5K trip using AP a lot on 2022.24.6. Middle of the day, straight interstate with no one close cruising at 80 and all of a sudden we slow to 40 or so before I can hit the go pedal. Happened 3 times in similar conditions - frustrating. And for some reason it wants to move to the passing lane though no one is ahead for a mile or so, happened many times. Still room for improvements!!

Great. And yet another reason to push back the 2022.24.6 “update.” I wonder if I can defer the install until 2022.28.n is more widespread and hope it’s better?

 

[DrGriz]

In the middle of a 2.5K trip using AP a lot on 2022.24.6. Middle of the day, straight interstate with no one close cruising at 80 and all of a sudden we slow to 40 or so before I can hit the go pedal. Happened 3 times in similar conditions - frustrating. And for some reason it wants to move to the passing lane though no one is ahead for a mile or so, happened many times. Still room for improvements!!

"It wants to move to the passing lane" seems very strange to me for basic AP. How did it go about that? I haven't heard of that problem before.

 

[Dennisis]

"It wants to move to the passing lane" seems very strange to me for basic AP. How did it go about that? I haven't heard of that problem before.

I have FSD with the lane change actually.

 

[DrGriz]

I have FSD with the lane change actually.

But not beta? OK, I see. Interesting.

 

[Dennisis]

But not beta? OK, I see. Interesting.

No not beta, can’t drive that carefully