Bugger! Drove from Noosa to Brisbane and back on the weekend and had 5 or 6 phantom breaking events in 'Autopilot'. It had happened occasionally in the past but this was much worse and quite unnerving.
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Phantom Braking / Slowdowns
- Thread starter Power Hungry
- Start date
Phantom brAking or phantom slow down?
I've experienced slow downs in the Tesla but I've never experienced phantom braking (have in several radar based vehicles though, ie a full ABS emergency lockup for absolutely no reason).
99% of the time when someone says phantom braking, when you actually dig into it, it was just a slow down of a few km/h. Even though I'm well aware of this I myself got caught out into thinking a slowdown recently was much more dramatic than it was. Main reason is I wasn't paying full attention, normally I have my foot over the accelerator and particularly when anything that happens which generally causes a slow down, I can catch it within 1-2km/h. This particular time I wasn't quite paying full attention and therefore it FELT like I slowed down dramatically.
Fortunately though I was filming at the time and it is actually published on youtube, when I went back and watched the video the speed only actually dropped 3-4km/h.
I think it's very important to be accurate when you are talking about this, usually the 'phantom' slow down has a reason, eg when you are passing a truck and it starts to wander towards the center line, the car can slow down, a car crossing on a highway in front of you (which seems to have improved based on my last trip), etc. Very different from when a radar based vehicle sees a false echo on a completely empty street and slams on the brakes, which I've had in both Mazda and BMW a couple of times each and my wife has had in the Toyota.
I get phantom "slow downs" as above every now and then, and yes its only a few kmh and usually when there is strong contrasts ie bright light and dark shadows where i assume the car is slowing to work it out.
I thought i had phantom braking last week... approaching a turn out on an 80kmh road and the brake pedal sunk to the floor, car didn't lock up but it stopped very quickly.
At first i thought, wow, thats phantom braking, but a second later a truck went barreling straight thru the give way sign in front of me at full speed.
The car definitely saved my life there as i didn't even see it coming and would never have stopped in time. For better or for worse im still here to tell the story. If i was still in my ICE car i would be getting washed off the front of a bull bar with a firehose.
you made one too many assumptions haha
Ahh yes, explains all the pubes
Yes I think you're right. It was probably more a slowdown although when doing 110km/h on an expressway, when the car drops into regen breaking mode, it definitely felt like a breaking incident. It frightened the crap out of my wife so much she demanded I actually drove the car myself. As I said, in over 11 months that had happened maybe twice, but last weekend, as I said, maybe 5-6 times.
BTW, we've owned 6 BMW's (330CI, X5's and 5 Series sedans) and an E Class BENZ and that has NEVER happened in any of them.
Yeah, don't mean to be pedantic, but I think it's important as they are two different things.
If I'm on AP I generally keep my foot over the accelerator for this reason, I think on my CBR-MEL-ADL-CBR trip I probably had 3 or 4 over the ~4000km. I expect 2 or 3 on a long trip, and there are certain spots where you can expect them, passing trucks is the one I find still applies, shadows can do it, but I haven't had any of those yet, a car crossing when you are over 100km/h has done it in the past, even if the car is over 100m in front, but on my last trip I was surprised to see it didn't react with a closer car crossing, (but still well enough in front that it wasn't going to present a danger).
I prefer it errs on the safe side, particularly when you hear of instances like above and see video of the car avoiding accidents that no other vehicle can avoid.
One thing I dont like about the Tesla is there is no right foot rest. A lot of cars don't have that either so I can't really complain except my VW Passat has a right foot rest to the right of the accelerator. Makes driving in Cruise control very easy and taking over pedal functions very easy and quick
Currently like you, I have to hover over the accelerator and it does make the heel of the foot a bit sore after a while.
In three years I've had a number of slow downs or hesitations. Like others, I do hover near the accelerator and sometimes give it a touch. Only ever one full-on brake event for me with a very sharp shadow a couple of years ago.
With respect to the slowdowns, I've sometimes thought "why did it slow down when the car crossing is a fair way in front." Then I've thought, if he slammed on the brakes would I still be able to stop in this lane? That explains some of them- a conservative driving approach.
Yes I understand that in some circumstances conservative driving approach might trigger an event. But, each 'slowdown' I had was at around 110 km/h on expressway conditions. There was no apparent reason the car would 'brake' as it did.
Max Spaghetti
Member
On certain parts of the Hume Hwy (both NSW and VIC sides) it will slow down approaching certain cross-roads (not all of them) - so not technically a controlled access motorway in those sections. There doesn't have to be any traffic around and it's repeatable every time. I tend to learn to predict when it will happen.
I wish they would fix it. But on the other hand it's not so annoying that I want to turn off TACC/Autosteer. The autopilot saves me so much fatigue and so many speeding tickets it's worth the pain. (But the adaptive cruise in my 2019 Ford Ranger does NOT do this. Ever.)
I'm hoping that when we get the US version of software running (even the basic V11 highway code) things will improve. Allegedly those with V11 FSDb had better highway performance than those without. And I don't think things will improve until that time - it's just not Tesla's focus right now. FSD is.
I sincerely agree with @Quickst about the fatigue in the right foot when attempting to hover above the accelerator pedal, or resting lightly on it. I tend to drive with heavy boots on so maybe that makes it worse, but to me it feels as though the accelerator pedal needs a stronger spring - I think it feels lighter than my previous vehicles, so harder not to accidentally press when lightly resting on it.
Having said that, I join in with @dronus at being impressed with a non-phantom braking event recently, although it was a bird rather than a rogue truck. Having already bent my number plate hitting a bird at 100km/h while ago, this time - it suddenly braked before I even saw the bird, and then I said thank you.
I wish they would fix it. But on the other hand it's not so annoying that I want to turn off TACC/Autosteer. The autopilot saves me so much fatigue and so many speeding tickets it's worth the pain. (But the adaptive cruise in my 2019 Ford Ranger does NOT do this. Ever.)
I'm hoping that when we get the US version of software running (even the basic V11 highway code) things will improve. Allegedly those with V11 FSDb had better highway performance than those without. And I don't think things will improve until that time - it's just not Tesla's focus right now. FSD is.
I sincerely agree with @Quickst about the fatigue in the right foot when attempting to hover above the accelerator pedal, or resting lightly on it. I tend to drive with heavy boots on so maybe that makes it worse, but to me it feels as though the accelerator pedal needs a stronger spring - I think it feels lighter than my previous vehicles, so harder not to accidentally press when lightly resting on it.
Having said that, I join in with @dronus at being impressed with a non-phantom braking event recently, although it was a bird rather than a rogue truck. Having already bent my number plate hitting a bird at 100km/h while ago, this time - it suddenly braked before I even saw the bird, and then I said thank you.
100% this! We've had VWs for the last 10 years so definitely missing the foot rest. For a car that is meant to be all about auto-driving it seems a bit of a weird omission!
Steve446
Dusty Crophopper, M3 LR 2021 Midnight Silver
I haven't had a phantom braking episode in a while with just one exception - when a motorway with two or three lanes splits into three or four lanes with autosteer on. Frequently the car can't decide which lane to take and jams on the brakes 
For slow downs I sometimes have the feeling that it's linked to bad local authority speed limit database maintenance. The last time I experienced that last week was at a junction that nominally was 80 km/hr with no slow down for straight through but I noticed the car had shown 50 on the screen before going back to 80.
For slow downs I sometimes have the feeling that it's linked to bad local authority speed limit database maintenance. The last time I experienced that last week was at a junction that nominally was 80 km/hr with no slow down for straight through but I noticed the car had shown 50 on the screen before going back to 80.
On the menu:
Controls > Autopilot > Set Speed and choose either Speed Limit or Current Speed.
I use the "Current Speed" setting for TACC rather than "Speed Limit" and never see these issues.
In every other car I've owned, while using cruise control I always kept my foot over the brake. With the Tesla, you learn to keep it over the accelerator instead..
I've learnt where is might hesitate and prepare, usually over hills or when there is a big change in contrast. Also its very sensitive to cars in emergency lanes etc
I've learnt where is might hesitate and prepare, usually over hills or when there is a big change in contrast. Also its very sensitive to cars in emergency lanes etc
Can a moderator please change the title to "Phantom Braking" NOT "Phantom Breaking"?
Totally different things.
Moderator: Done.
Totally different things.
Moderator: Done.
Last edited by a moderator:
This. I always keep my foot on the accelerator pedal when I can see a car in the breakdown lane ahead. Otherwise TACC has conniptions and thinks you need to slam the brAkes on.
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