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Speed Changing with TACC,FSD, or Basic Cruise Control?

spokey

Member
Aug 8, 2020
889
475
Flagtown
Can't find any reference to this in the manual and I note others seem to have some problems with car changing speed when the speed limit goes up or down on the road.

So my question is

How is this supposed to work? No matter what mode I put it in (i.e. single/double stalk engage) the car will accelerate up to the limit if I'm below it and stay at the speed I'm at if I'm above the limit. So I've got that part. But my speed never goes up or down when the speed limit changes. Is there some setting for that? Under what circumstances is it supposed to or not change?

The car is aware of the current speed limit because I get the chime when I go over it. It just doesn't change speed when the speed limit changes.
 

EVRider-FL

Active Member
Aug 18, 2015
1,010
577
South Florida
TACC does not automatically adjust to speed limit changes, but there are conditions where it will slow down, documented in the manual. The same is true when using Autosteer or NoA, but those have additional restrictions that might limit your speed. Basic cruise control only exists in older cars without any form of AP, and I’ve never seen documentation for that in any version of the manual I’ve looked at.
 

spokey

Member
Aug 8, 2020
889
475
Flagtown
DOe
TACC does not automatically adjust to speed limit changes, but there are conditions where it will slow down, documented in the manual. The same is true when using Autosteer or NoA, but those have additional restrictions that might limit your speed. Basic cruise control only exists in older cars without any form of AP, and I’ve never seen documentation for that in any version of the manual I’ve looked at.
I'm aware of it slowing because of the vehicle in front of it and lights and such. Sometimes it will even slow down around a curve.

Does FSD change with the speed limit changes? There are certainly threads here that talk about the car changing speed based on a change in the speed limit although the threads seem to also indicate that it doesn't work very well.

One thing I found disconcerting in the manual was that the emergency braking is not meant to avoid a crash but to minimize it. P 118

Automatic Emergency Braking

Model Y is designed to determine the distance from a detected object traveling in front of it. When a frontal collision is considered unavoidable, Automatic Emergency Braking is designed to apply the brakes to reduce the vehicle's speed and therefore, the severity of the impact. The amount of speed that is reduced depends on many factors, including driving speed and environment.
 

spokey

Member
Aug 8, 2020
889
475
Flagtown
Page 86 of the manual, tap the speed limit sign on the screen and the car will change to the new limit.
I understand that and I believe I have used that upon occasion and it has worked. But there are threads here that (at least seem to) indicate that one of these (FSD only?) will lower and raise with changes in the speed limit
 

Fistobar

Member
Sep 3, 2020
22
11
Tasmania, Australia
When in FSD the speed will change to the new limit, but not always and I haven’t worked out the reasoning. I must admit I mostly just spin the right control wheel to manually reset the limit (pretty quick if you do it fast, 5kph)
 

hugh_jassol

Member
Jan 26, 2019
803
909
Los Angeles
The regular FSD available to the masses doesn’t adjust to speed limit changes, unless Tesla changed that behavior recently.
It sure does. There's a stretch of freeway I drive every morning that has speed limit 65, but the car thinks it's 55 for about 1/4 mile... so it adjusts down and I have to scroll wheel it back up.

It's done this for some time - one thing they added in the last 6 months or so was the speed limit sign reading. You can check YouTube ... there's at least of few videos of you tubers trying to be first to post it.
 
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spokey

Member
Aug 8, 2020
889
475
Flagtown
When in FSD the speed will change to the new limit, but not always and I haven’t worked out the reasoning. I must admit I mostly just spin the right control wheel to manually reset the limit (pretty quick if you do it fast, 5kph)
that's what I"m doing now. Spinning the wheel. I tend to go slow, particularly up
 

EVRider-FL

Active Member
Aug 18, 2015
1,010
577
South Florida
Interesting. I haven’t taken a road trip since last fall, but AP definitely did not adjust to speed limit changes at that time. I’m not sure I’ll like the new behavior, especially when the car doesn’t accurately detect the speed limit.
 

Wnuk

Member
Jul 9, 2017
368
1,148
PA
My 2018 with FSD is funny with this. If I’m on a road that has a speed limit of say 45 and then it changes to 55, my car won’t react to it and I need to change the speed manually. But if it notices a slower speed limit it will drop down to it on its own
 

bedoig

Member
Nov 29, 2016
600
913
The Woodlands, TX
On undivided highways and side roads it adjusts downward to the speed limit +5mph maximum. If it adjusted itself down it will also adjust itself back up when the speed limit rises (and you haven't played with it in between). On divided highways there is no maximum over the speed limit (other than 90mph) so it doesn't adjust. As others have noted you can tap the speed limit sign, use the scroll wheels, or do a long press down on the right stalk to adjust to speed limit + set offset.
 

spokey

Member
Aug 8, 2020
889
475
Flagtown
On undivided highways and side roads it adjusts downward to the speed limit +5mph maximum. If it adjusted itself down it will also adjust itself back up when the speed limit rises (and you haven't played with it in between). On divided highways there is no maximum over the speed limit (other than 90mph) so it doesn't adjust. As others have noted you can tap the speed limit sign, use the scroll wheels, or do a long press down on the right stalk to adjust to speed limit + set offset.
Do you mean AP, TACC or FSD? Is there any setting for that? As originally posted, mine does not. So you're saying that if I'm on a big interstate doing the limit at say 65 and the speed drops to 55 (as it does often at least around here), the car stays at 65 (assuming it isn't slowed by the car ahead of it)?

What is the long press? Pull all the way (past the detent) and hold? That sounds easier than scrolling.
 

bedoig

Member
Nov 29, 2016
600
913
The Woodlands, TX
Do you mean AP, TACC or FSD? Is there any setting for that? As originally posted, mine does not. So you're saying that if I'm on a big interstate doing the limit at say 65 and the speed drops to 55 (as it does often at least around here), the car stays at 65 (assuming it isn't slowed by the car ahead of it)?

What is the long press? Pull all the way (past the detent) and hold? That sounds easier than scrolling.

I think it's an Autosteer restriction that drives that behavior, so if you're on TACC only I don't think the speed will drop. It's more a byproduct of Autosteer speed restrictions on side roads / undivided highways (speed limit +5mph) than intelligent speed adjustment to respect speed limits. Correct that it won't adjust on major interstates. I don't think it's really configurable, it's just that autosteer enforces the limit +5mph ceiling on non-interstate roads.

The long press is just holding at the first soft detent for like 2-3 seconds (on 3/Y at least, not sure if there's any equivalent for other models).
 

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