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Losing my mind over the random slowdowns

KiloV

Member
Jun 26, 2019
33
75
YYC
Have the option to turn off Adaptive Cruise Control and just use regular CC. Adaptive Cruise Control has a tendency to slow down very abruptly when you don't want it to and speed up when it shouldn't.
OMG, I'd pay $10K for this. I find I'm constantly fighting the so-called "TACC", because it's neither traffic- nor speed-limit aware. Some of the stupidity I've come to hate:

I'll set the cruise just above the posted speed as I come into a new speed zone, and it'll immediately drop the setting back to the posted limit. Why? I literally just set a speed, just do what I asked!

I'll come into a slower speed zone, but traffic hasn't yet slowed down, and TACC will set the lower limit immediately and start decelerating... why does TACC need to brake-check the traffic behind me? Just go with the flow FFS!

In construction zones, TACC constantly ignores the set speed (lower than posted speed) and tries to accelerate to either a) the posted temporary speed limit, or worse b) the full speed limit from the road (take from an internal database, or something?). Either way, it's suddenly jumping at the car in front of me or trying to blast through the construction zone. Why? I set a safe speed, just obey the speed setting!

I've come to hate TACC/AP/FSD over the past few weeks - it was bad before, but the FSD beta has made it terrible.

My worst fear about TACC/AP/FSD is Elon's comment that "all input is error" - it's totally backwards. Human input is a statement of intentions, and the system's job should be to follow the human's intent, except where it's obviously unsafe (e.g. accelerating into a storefront). If this is the driving philosophy behind Tesla, I suspect my M3 is going to get even more undrivable.
 

Snerruc

Unqualified Doofus
Apr 16, 2016
1,269
3,170
Palm Bay
OMG, I'd pay $10K for this. I find I'm constantly fighting the so-called "TACC", because it's neither traffic- nor speed-limit aware. Some of the stupidity I've come to hate:

I'll set the cruise just above the posted speed as I come into a new speed zone, and it'll immediately drop the setting back to the posted limit. Why? I literally just set a speed, just do what I asked!

I'll come into a slower speed zone, but traffic hasn't yet slowed down, and TACC will set the lower limit immediately and start decelerating... why does TACC need to brake-check the traffic behind me? Just go with the flow FFS!

In construction zones, TACC constantly ignores the set speed (lower than posted speed) and tries to accelerate to either a) the posted temporary speed limit, or worse b) the full speed limit from the road (take from an internal database, or something?). Either way, it's suddenly jumping at the car in front of me or trying to blast through the construction zone. Why? I set a safe speed, just obey the speed setting!

I've come to hate TACC/AP/FSD over the past few weeks - it was bad before, but the FSD beta has made it terrible.

My worst fear about TACC/AP/FSD is Elon's comment that "all input is error" - it's totally backwards. Human input is a statement of intentions, and the system's job should be to follow the human's intent, except where it's obviously unsafe (e.g. accelerating into a storefront). If this is the driving philosophy behind Tesla, I suspect my M3 is going to get even more undrivable.
If you don’t want the car to slow down when you enter a slower speed zone, just accelerate to the speed you want and then set TACC. If you just start TACC before reaching speed, it. Defaults to your preset over speed ( +5 or 10% over or mph over ). Note, even 1 mph over default works on my S. However, the onus is now on you to adjust speed to the new limit. As far as construction zones, the cars don’t recognize most construction limit signs yet. If they are using standard speed limit signs, the cars see them. This seems to be a rare case. All this is a known problem on most cars with some form of TACC. There are government investigations on some makes. If you set a cruise speed and the car drops to the limit, check your over setting. It may have been changed in an update. Also, it might have been corrupted in an update. I’ve had things like that happen. If resetting your mph over doesn’t solve the problem, put in a ticket with Tesla. They can read your car and see a problem most of the time. They fixed a similar type of problem on my car. Good luck!
 
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nvx1977

Unknown Member
Nov 25, 2017
3,073
7,231
NH, MA
FSD beta, although I get the sense from comments that most of the slowdown concerns are coming from Vision owners, FSD beta or otherwise. Maybe I’m off base on that, though? I remember in the early days of my 2019 Model 3, phantom braking was rough with underpasses, but that got resolved ages ago.

I'm likely in the minority, but I very rarely get any sort of phantom braking on the highway. I'm on FSD beta 10.11.2 and use it on the highway all the time. I just got done with a 400-mi trip and had no phantom braking. Back in the radar days, I would invariably get the occasional freakout for a sign or overpass. This was never resolved for me, up to the point I got into the closed beta. That issue has been completely resolved for me on vision-only.

I can't explain why so many people have more PB on vision-only. I can only assume that the system works better on the hardware on my car (a first-production LR RWD).

When I use FSD-beta on local roads, my foot hovers over the accelerator so I can override any whimsical hesitations or phantom braking events. On the highway, I can relax my foot on the floormat because PB just isn't an issue anymore.
 
I'm likely in the minority, but I very rarely get any sort of phantom braking on the highway. I'm on FSD beta 10.11.2 and use it on the highway all the time. I just got done with a 400-mi trip and had no phantom braking. Back in the radar days, I would invariably get the occasional freakout for a sign or overpass. This was never resolved for me, up to the point I got into the closed beta. That issue has been completely resolved for me on vision-only.

I can't explain why so many people have more PB on vision-only. I can only assume that the system works better on the hardware on my car (a first-production LR RWD).

When I use FSD-beta on local roads, my foot hovers over the accelerator so I can override any whimsical hesitations or phantom braking events. On the highway, I can relax my foot on the floormat because PB just isn't an issue anymore.
For me, highways have generally been pretty good. I do get the occasional slow down, but the real problem is 2 lane roads like county roads and state highways. I'm on FSD 11.2, too and just got back from our cabin. Half the trip was on the interstate and went fine. The other half was on a 2 lane state highway and PB events were still abundant.
 

Yelobird

Active Member
Aug 24, 2020
1,594
2,125
Illinois
Can confirm that my wife will not ride in the car with even just cruise control on due to phantom braking. It is VERY frustrating that they haven't fixed this issue. I will grant that it is a rare event but it only takes one (like yesterday) to reset my wife to zero tolerance.
Hmmm sounds like a win to me. I don’t have PB but if all I have to do is slam on the brakes a few times to have my wife not drive with me I’m in.
 
OMG, I'd pay $10K for this. I find I'm constantly fighting the so-called "TACC", because it's neither traffic- nor speed-limit aware. Some of the stupidity I've come to hate:

I'll set the cruise just above the posted speed as I come into a new speed zone, and it'll immediately drop the setting back to the posted limit. Why? I literally just set a speed, just do what I asked!

I'll come into a slower speed zone, but traffic hasn't yet slowed down, and TACC will set the lower limit immediately and start decelerating... why does TACC need to brake-check the traffic behind me? Just go with the flow FFS!

In construction zones, TACC constantly ignores the set speed (lower than posted speed) and tries to accelerate to either a) the posted temporary speed limit, or worse b) the full speed limit from the road (take from an internal database, or something?). Either way, it's suddenly jumping at the car in front of me or trying to blast through the construction zone. Why? I set a safe speed, just obey the speed setting!

I've come to hate TACC/AP/FSD over the past few weeks - it was bad before, but the FSD beta has made it terrible.

My worst fear about TACC/AP/FSD is Elon's comment that "all input is error" - it's totally backwards. Human input is a statement of intentions, and the system's job should be to follow the human's intent, except where it's obviously unsafe (e.g. accelerating into a storefront). If this is the driving philosophy behind Tesla, I suspect my M3 is going to get even more undrivable.
You do know you can set the speed limit behavior, right? Go to the AutoPilot menu in settings and change it to just use your current speed. Of course it won’t automatically slow down for you when the speed limit changes.
 

rjpjnk

Active Member
Mar 12, 2021
1,386
984
NJ
I've tolerated the random slowdowns and occasional false AEB since I joined the FSD beta and Tesla stopped using my radar, but then I drove 700 miles this weekend, mostly on two-lane highways.

Oh my god. Toward the end of this trip, I started cracking. I started dreaming of installing an aftermarket cruise control kit, and actually looked them up. (For many obvious reasons, no such Tesla-compatible accessory exists.)
Are you sure having the radar makes it any better? I’ve heard plenty of stories that claim AP/TACC is just as bad with or without radar. It sounds like in your case the it made a big difference. When you run with FSD with radar deactivated is it the same exact performance of vision only cars without FSD? Wish I could try one with radar to see for myself.
 

rjpjnk

Active Member
Mar 12, 2021
1,386
984
NJ
My worst fear about TACC/AP/FSD is Elon's comment that "all input is error" - it's totally backwards. Human input is a statement of intentions, and the system's job should be to follow the human's intent, except where it's obviously unsafe (e.g. accelerating into a storefront). If this is the driving philosophy behind Tesla, I suspect my M3 is going to get even more undrivable.
I think this is exactly what Elon’s comment means. The human driver’s actions are the truth data, and by definition are the correct response. Any time the driver has to intervene to correct the car’s decisions this human input represents the error signal to the Automated system. It indicates where the system has failed. Hence, all input is error. Perhaps he should have said all input is correction?

At least that’s how I read it based on a control theory model.
 

KiloV

Member
Jun 26, 2019
33
75
YYC
You do know you can set the speed limit behavior, right? Go to the AutoPilot menu in settings and change it to just use your current speed. Of course it won’t automatically slow down for you when the speed limit changes.
I’m pretty sure I know how the settings are supposed to work, because I’ve been living with TACC for 4 years. This seems to be a problem with the FSD stack.

The problem I have is that it DOES automatically slow down when the speed limit changes. And it DOES automatically speed up when (it thinks) the speed limit changes.

Every time I enter a new speed zone, it decides to reset the cruise speed. Even when I’ve JUST set it at the start of the zone, it resets on me.

I don’t want it to do either of these things. I just want it to hold the last speed I set. Simple.
 
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KiloV

Member
Jun 26, 2019
33
75
YYC
I think this is exactly what Elon’s comment means. The human driver’s actions are the truth data, and by definition are the correct response. Any time the driver has to intervene to correct the car’s decisions this human input represents the error signal to the Automated system. It indicates where the system has failed. Hence, all input is error. Perhaps he should have said all input is correction?

At least that’s how I read it based on a control theory model.
“All input is training data” or “all input is an error signal” is very different than “all input is error”.

I hope he wouldn’t misstate that, but who knows. He’s not what I’d call a glowing presenter. ;)
 
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I’m pretty sure I know how the settings are supposed to work, because I’ve been living with TACC for 4 years. This seems to be a problem with the FSD stack.

The problem I have is that it DOES automatically slow down when the speed limit changes. And it DOES automatically speed up when (it thinks) the speed limit changes.

Every time I enter a new speed zone, it decides to reset the cruise speed. Even when I’ve JUST set it at the start of the zone, it resets on me.

I don’t want it to do either of these things. I just want it to hold the last speed I set. Simple.
Then disable FSD.
 
“All input is training data” or “all input is an error signal” is very different than “all input is error”.

I hope he wouldn’t misstate that, but who knows. He’s not what I’d call a glowing presenter. ;)
Elon's tweets are never both accurate and clear. The times he makes a clear tweet it's not accurate. The rest of the time you can only say it's accurate because it's so ambiguous.
 
I dunno, I'm just using the FSD Beta all the time - freeways and streets - and it works great, certainly well enough on the whole. I set my speed offset to -5 MPH and adjust target max speed with the roller all the time, and I use the accelerator whenever I want to. If the car reads a billboard number as a speed limit sign, or slows down on a possibly threatening situation and gets confused, it takes a second to correct.

My role is to supervise and make choices. Active supervision, engagement. The system's role is to drive, steering and navigating. Most of the time I just watch, it's gotten really good. I never use TACC or any half-measures. We work very well together. If I'm late to an appointment, I drive aggressively, completely in manual.

I think it involves a real learning curve and adaptation, as it's a very different way to drive and it requires change. People who are happy with it have figured this out. Either you want it, and start from exploring how to best use it, or you don't. I do. FWIW it took me a month or two of significant discomfort at first in early 2019. Don't ask about the wife. But at this point I wouldn't give this up for anything, and my passengers are fine.
 
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