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Reduce/eliminate phantom braking (trigger warning)

Marius A

Member
Apr 2, 2019
612
525
NORWAY
Some weeks ago I posted a poll on how often people experience phantom braking, and the results were around 50% for "Almost never" and the rest spread out over "seldom" to "almost always". That's a really high number so I decided to test out different strategies to improve it (I was one of the "almost always" voters). This is the results from my testing.

Car: October build Model 3 Performance. Autopilot, no FSD. No vinyl, no PPF, no wax, no coating. 2020.12.6
Road: 50km of high speed (100-110km/h), 15km of medium speed (60-80km/h) two lane highway each way and physical separator between driving directions (by the book). In total 120km+ round trip every time on AP. Plenty of ramps, a lot of trailers, plenty of other cars.
Timing: Always middle of the day, no traffic going out, heavy traffic going back.

Test method
Always activate Autopilot, and keep on as much as possible. If not possible, use TACC (but this never occurred). Switch lanes responsibly, use several seconds or wait for the next chance. Abort lane change over speeding up.

Base line. Dirty car, collision detection set to early. 2x sunny days:
Phantom braking happens a lot. Nearly every trailer I pass causes braking, all overhead passes causes emergency braking, and switching lanes sometimes cause a minor brake situation. It's quite untolerable and I felt awful driving like this not only on round-trip, but two. It was not something I would be OK living with.

Second test. Clean car, collision detection set to early, 1 sunny day, 1 cloudy day:
It seems like phantom braking happens just as often. I had washed the car the day before, so I pulled over mid-trip to go over the radars and the cameras with a clean microfiber cloth. It did not make a difference, and I felt like a real danger in traffic just waiting for the car to suddenly brake again. I washed the car again (machine wash, shame on me) the next week and tried again on a cloudy day, but it was still as bad. Direct sunlight vs cloudy didn't seem to have any difference in the phantom braking effect.

Third test. Clean car, collision detection set to late, sunny day:
I didn't experience any phantom braking, but the follow distance seemed WAY off in this setting. I came up really close to cars in front of me before the car decided to start braking. It felt extremely aggressive, and I was worried people would get mad at me. I was really not comfortable on my way home again in heavy traffic. I braked manually many times because I didn't like how close I got before it did the job itself. Setting follow distance to 7 helped, but this left a gap that even trailers utilized so it wasn't really my cup of tea.

Fourth test. Dirty car, collision detection set to medium. Rainy day:
No phantom braking experienced for the whole trip. Follow distance when cars braked in front of me was uncomfortable, but I adjusted the follow distance up from 3 (what I used with early collision detection) to 5. This was quite an enjoyable ride, and let me drive all the way without any incidents.

Fifth test. Dirty car, collision detection set to late. Cloudy day:
Pretty much the same as the first time I set to late. I switched back to medium on my way home because I didn't like this setting, and it was stressful in stop-and-go traffic.

Sixth test. REALLY dirty car, collision detection set to medium. Rainy day:
Same as the previous time I set it to medium, except I had a valid emergency brake due to a motorcycle acting like a lunatic. It came pretty close but nobody was hit. 5 seems like the sweet point on follow distance for me. Set to 1 it works pretty well in stop-and-go queues.

Seventh test. Dirty car, collision detection set to medium. Really bright, sunny day:
No difference from other tests on medium. This is my go-to setting right now.

Wrap up
On my car it seems that the only setting which really matters is the collision detection settings. Dirty or clean made no noticable difference, and sharp, direct sunlight and rain had no effect on AP performance.
I would like to note that this is my second TM3, and the first one also had awful phantom braking. I did not, however, perform these tests with that car.

Now I can finally install 2020.16 :)
 

jpfive

Member
Supporting Member
Oct 31, 2019
565
543
Pensacola, FL
Some weeks ago I posted a poll on how often people experience phantom braking, and the results were around 50% for "Almost never" and the rest spread out over "seldom" to "almost always". That's a really high number so I decided to test out different strategies to improve it (I was one of the "almost always" voters). This is the results from my testing.

Car: October build Model 3 Performance. Autopilot, no FSD. No vinyl, no PPF, no wax, no coating. 2020.12.6
Road: 50km of high speed (100-110km/h), 15km of medium speed (60-80km/h) two lane highway each way and physical separator between driving directions (by the book). In total 120km+ round trip every time on AP. Plenty of ramps, a lot of trailers, plenty of other cars.
Timing: Always middle of the day, no traffic going out, heavy traffic going back.

Test method
Always activate Autopilot, and keep on as much as possible. If not possible, use TACC (but this never occurred). Switch lanes responsibly, use several seconds or wait for the next chance. Abort lane change over speeding up.

Base line. Dirty car, collision detection set to early. 2x sunny days:
Phantom braking happens a lot. Nearly every trailer I pass causes braking, all overhead passes causes emergency braking, and switching lanes sometimes cause a minor brake situation. It's quite untolerable and I felt awful driving like this not only on round-trip, but two. It was not something I would be OK living with.

Second test. Clean car, collision detection set to early, 1 sunny day, 1 cloudy day:
It seems like phantom braking happens just as often. I had washed the car the day before, so I pulled over mid-trip to go over the radars and the cameras with a clean microfiber cloth. It did not make a difference, and I felt like a real danger in traffic just waiting for the car to suddenly brake again. I washed the car again (machine wash, shame on me) the next week and tried again on a cloudy day, but it was still as bad. Direct sunlight vs cloudy didn't seem to have any difference in the phantom braking effect.

Third test. Clean car, collision detection set to late, sunny day:
I didn't experience any phantom braking, but the follow distance seemed WAY off in this setting. I came up really close to cars in front of me before the car decided to start braking. It felt extremely aggressive, and I was worried people would get mad at me. I was really not comfortable on my way home again in heavy traffic. I braked manually many times because I didn't like how close I got before it did the job itself. Setting follow distance to 7 helped, but this left a gap that even trailers utilized so it wasn't really my cup of tea.

Fourth test. Dirty car, collision detection set to medium. Rainy day:
No phantom braking experienced for the whole trip. Follow distance when cars braked in front of me was uncomfortable, but I adjusted the follow distance up from 3 (what I used with early collision detection) to 5. This was quite an enjoyable ride, and let me drive all the way without any incidents.

Fifth test. Dirty car, collision detection set to late. Cloudy day:
Pretty much the same as the first time I set to late. I switched back to medium on my way home because I didn't like this setting, and it was stressful in stop-and-go traffic.

Sixth test. REALLY dirty car, collision detection set to medium. Rainy day:
Same as the previous time I set it to medium, except I had a valid emergency brake due to a motorcycle acting like a lunatic. It came pretty close but nobody was hit. 5 seems like the sweet point on follow distance for me. Set to 1 it works pretty well in stop-and-go queues.

Seventh test. Dirty car, collision detection set to medium. Really bright, sunny day:
No difference from other tests on medium. This is my go-to setting right now.

Wrap up
On my car it seems that the only setting which really matters is the collision detection settings. Dirty or clean made no noticable difference, and sharp, direct sunlight and rain had no effect on AP performance.
I would like to note that this is my second TM3, and the first one also had awful phantom braking. I did not, however, perform these tests with that car.

Now I can finally install 2020.16 :)

Thanks for putting the work into this. Your experience mirrors mine. I use the late setting almost always. I found that in local driving the biggest trigger for phantom braking is cars approaching the highway from side streets, regardless of whether they are stopping normally or aggressively approaching the merge. Even with late braking I stay very alert to disengage when I see vehicles approaching in this way. On Interstates I find the problem confined almost always to exits and merging lanes, and also to shifting of lanes due to construction. I disengage approaching these areas as a matter of course.

Bottom line. I find TACC and AP to be indispensable aids to this 73 year old man. However, I have never considered the car to be "self driving" and always stay fully engaged with piloting the car. It is always my responsibility, never the car's. (edited for conclusion)
 
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grmdl3

Member
Apr 21, 2020
154
112
Oregon
This is great, and a little reassuring since the fix seems to be software, not hardware. It would be REALLY disconcerting if the issue were caused by sensors that could be tricked by bug splatter or dirt.
 

Marius A

Member
Apr 2, 2019
612
525
NORWAY
This is great, and a little reassuring since the fix seems to be software, not hardware. It would be REALLY disconcerting if the issue were caused by sensors that could be tricked by bug splatter or dirt.
It certainly seems so. Also means that you don't have to treat your car like a fragile, glass ornament.
 

EV Promoter

Member
Nov 30, 2019
335
998
Europe
Some weeks ago I posted a poll

Can i ask if is possible:

- to exclude the automatic braking at all
- to set the TACC as a normal non-braking Smart CC
- set the AEB max speed of action

Am i forced to use a car without the most basic CC to avoid major issues?
Will be impossible to exclude AEB in any case (even TACC excluded) ?

I see most of car producers sets AEB at quite low speed, say 50-60 km/h, to avoid major problems due to phantom braking at high speed, and old tests from the EU NCAP shown EU Model 3 at the same level of max speed of intervention. Then it changed, perhaps with a progressive increase of that speed limit.

It is clear that Tesla felt more daring of the average, but i see there's pretty good reasons to revert back to safer speed limits,
It does not seems an issue that can be software-controlled more than this...
 
Last edited:

Fernand

Active Member
Mar 22, 2019
1,622
1,797
Northern california
I can't say what European regulations are requiring, but thankfully in the US Tesla has been unshackled. We've had a chance to experience everything (positive and negative) that the tech can deliver.

From end 2018 until the last 2 months I have had very very few phantom slowdowns, like 2-3 in over a year. Collision detect always set to early, lane change set to Mad Max. The freeway EAP/FSD was excellent, handling full speed end to end no-intervention Navigate on Autopilot, including bridges, multiple horrifying freeway splits/merges etc at 65-75 MPH, like this itinerary. You can navigate on the google map, and see all the merges and overpasses, like my most unfavorite split. Like other M3s with HW2.5 it stopped yielding the passing lane around late 2019.

After installing HW3 and newer software it has a different character since ~July 2020. It does yield the passing lane very politely. No problems with overpasses, BUT I've had unnecessary slowdowns occasionally when approaching merging traffic on freeways - something that might be considered "phantom braking". It's an irritating regression since it used to muscle its way between merging cars very well. Awaiting next version improvements.

BTW, I'm sorry your car performs as so-so whether clean or dirty, but that's not much of an argument, is it? :)
.
 
Last edited:
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john5520

Active Member
Mar 3, 2020
1,047
855
Florida
My phantom braking happened regardless of what the collision detection system was set to. I set it to medium mostly, but ran it on late (forum members said it helped)for a few weeks, and it made no difference. It's back on medium now.

The good news for me, is that since the last update, it seems to be happening a lot less. And when it slows around larger vehicles it's very manageable now, rather than abrupt like before.
 

ftmaybe

Member
Feb 11, 2020
258
377
San Joaquin
I have gotten phantom braking quite a bit, at least once or twice a week. Normally you'd expect something influenced it like a shadow or a truck, however a few weeks ago I had my worst case of phantom braking on a city street in broad daylight. No shadows, no other cars... just decided to slam on the brakes for about 1 second before resuming. Bloody annoying.
 

Brock-WI

Member
Aug 4, 2020
86
70
Green Bay, WI
We just drove 600 miles in a day and we had 6 phantom braking instances. All on highway driving, 3 of them we knew what caused them (overpass or weird pavement coloring), 3 were totally out of nowhere. One of them was while we had a car close behind us, it was scary, I know people shouldn't follow so close, but I am sure they were within a foot of our back bumper after slamming on their brakes. I almost wondered if our car was annoyed we were being tailgated and brake checked the car behind us. Again on that one there was nothing anywhere in front of us, lighting or color wise.
 

TLLMRRJ

Active Member
Dec 19, 2019
2,054
2,452
Houston
Anyone try the new version that can read the speed signs? That at least should help with the slowdowns for false speed changes...hopefully.
 

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