I don't see any cues visually that the car should interpret as a speed limit, so this must be a mapping bug, very specific to that location.I got curious enough drive through the same route and try to reproduce what happened, and I had no problem reproducing it two times in a row.
While driving in TACC at between 60-70mph, the set speed simply jumps up to 90mph right after the speed limit sign on the screen changes to 70mph. (Side note: there are no actual 70mph speed limit signs.) Doesn’t appear to matter whether or not I’m manually increasing the set speed with the scroll wheel like the first time it happened. I tried it once each way.
I took a video and here are before/after screenshots taken a fraction of a second before and after the set speed jumps up to 90mph. The full video is at th bottom, and the jump happens at the 14-second mark.
Before: 65mph set speed.
View attachment 682437
0.1 seconds later: 90mph set speed.
View attachment 682438
I have experienced something similar when letting AutoPilot drive between two interstate highways.It just happened again, but this time on a different interchange: driving from Northbound I-355 onto Westbound I-88 (in the western Chicago burbs).
TACC set speed was ~65mph going through the interchange. Then near the end of the ramp it jumped to 90mph.
I’m surprised there aren’t more posts on this. I can’t believe I’m the only one this is happening to. And it’s such a bizarre behavior.
That’s what I suspected at first, but there’s no slowdown at all on the interchange mentioned in the first post. (EB IL-56 onto EB I-88)I have experienced something similar when letting AutoPilot drive between two interstate highways.
When you are on the original highway, the car is going your set speed (presumable speed limit plus offset). Then, when you move from the highway to the off ramp, the car has a database with the speed for that off ramp. The car will slow to that speed. For me, it has always been lower than the main highway, but I don't know if that is universal.
Since this is an interchange between two highways, the off ramp becomes an on ramp for the second highway. As you get close to the merge point, the car either reads a new speed limit sign or pulls from it's database the speed for the second highway. The car will then accelerate up to the new speed limit plus your offset.
If this is what is happening to you, then the car is just slowing down for the transition between the highways. I know that some transitions do not have sharp turns and the highway may not visually look different, so cars may travel at the same speed between the highways. But the car thinks it should be slowing down, so it does.
Not sure if this is exactly what you are seeing, but I have experienced it at just about every transition between highways I can remember.
A couple of observations: your set speed is always 15-30mph higher than the speed limit throughout your video. What is your speed offset setting in TACC? Please show that setting concurrently with your video.I took the Northbound I-355 onto Westbound I-88 interchange again. This time I drove through it with TACC engaged and made sure not to touch the scroll wheel at any point, and it still raised the set speed to 90mph at the end of the interchange.
I entered the interchange with the set speed at 65mph. The car lowered the set speed on its own, first to 60mph and then again to 55mph as it went through the curve. Then it raised it to 60mph. And then towards the end of the ramp it raised it to 90mph.
Video (set speed jumps at 0:47) (sorry for the shakiness and orientation) :
A couple of observations: your set speed is always 15-30mph higher than the speed limit throughout your video. What is your speed offset setting in TACC? Please show that setting concurrently with your video.
But to fully understand what's happening when you apparently set your speed 15-20mph higher than the speed limit before it changes to 30mph higher (by itself), set your offset to zero, then set the cruise when you enter the offramp to the speed limit (40mph), and repeat this experiment.
Well, hopefully Tesla gets to the bottom of that, as I agree it potentially could be dangerous.I’ve noted repeatedly in this thread that I don’t use a speed limit offset setting for the set speed. My set speed setting is to engage at the current vehicle speed. This behavior has nothing to do with speed limit offsets in the set speed settings.
Also, FYI: prior to the start of the video, and before entering the interchange, I had initially engaged TACC at a set speed of 65mph when the speed limit was 60mph. The speed limit sign on the screen later briefly disappears after entering the interchange (due to lack of nav system data, I suppose), but you can see that the set speed is still 65mph at the start of the video before the speed limit sign reappears as 40mph.
What is your speed offset setting in TACC?
I don’t use a speed limit offset setting for the set speed. My set speed setting is to engage at the current vehicle speed. This behavior has nothing to do with speed limit offsets in the set speed settings.
Try enabling the offset and setting it to zero, then disabling it?Turns out I was wrong about this bug not being related to the Autopilot Set Speed speed limit offset setting...
Even though I have the Set Speed setting toggled to engage at the current vehicle speed with no speed limit offset, my car is still using the "greyed-out"/disabled speed limit offset setting (which for some reason I had set to +30mph) and applying that offset to automatically change my set speed on almost every highway on-ramp that I take. (The speed limit offset value is still retained in the vehicle settings even after you toggle back to using current speed. You can still see it in the Autopilot settings menu -- it's just greyed out.)
I verified this by changing the speed limit offset setting to a bunch of different settings, and the set speed reliably jumps to whatever that offset speed is on the vast majority of on-ramps. This happens equally whether the offset is set to a MPH offset or a % offset, and it also happens whether I leave the offset setting engaged or toggle back to Current Speed.
So it's really like 2 bugs in one:
I do still wonder if this bug is somehow unique to my vehicle, or if this is a widespread bug that's just flying under the radar since it's unusual to engage TACC/AP on on-ramps.
- It's automatically increasing the set speed in the middle of on-ramps, which it's not suppose to do. (Note that TACC/AP can automatically decrease the set speeds when driving through interchanges and then later increase it back to the original set speed, as described in the owner's manual. But it's not supposed to randomly increase speeds based on speed limit offsets on on-ramps.)
- It's using the speed limit offset setting, even though I have that disabled.
I would say not, all cars have the same software. I do engage TACC/AP a LOT on ramps. I think the unusual setting is a +30mph offset, I never heard of anyone setting it over 15mph.I do still wonder if this bug is somehow unique to my vehicle, or if this is a widespread bug that's just flying under the radar since it's unusual to engage TACC/AP on on-ramps.
Try enabling the offset and setting it to zero, then disabling it?
I would say not, all cars have the same software. I do engage TACC/AP a LOT on ramps. I think the unusual setting is a +30mph offset, I never heard of anyone setting it over 15mph.