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High speed braking instability - ABS/ESP bug?

Realist

Member
Jun 10, 2013
321
80
Germany
Hello,

I drive a Model 3 Performance here in Germany. Car is limited at 250kph.

I can confirm the bug. Through fast corners at speed above 200 kph the ABS Systems seems to overreact, creating instability.

Best way to avoid is to brake very gently or go slower. Track Mode does make no difference here.

You clearly see that the car has never been tested on the Nürburgring Nordschleife. The steering is also way too nervous at high speed.
 

OPRCE

Member
Jun 16, 2018
860
768
Bern, CH
Hello,

I drive a Model 3 Performance here in Germany. Car is limited at 250kph.

I can confirm the bug. Through fast corners at speed above 200 kph the ABS Systems seems to overreact, creating instability.

Best way to avoid is to brake very gently or go slower. Track Mode does make no difference here.

You clearly see that the car has never been tested on the Nürburgring Nordschleife. The steering is also way too nervous at high speed.

Wow, so it looks like all M3s have the same problem then (and probably not just in Germany) ... what has Tesla said about this? ( @electrifier also)

Really there should be some official notification pushed to the in-car display warning all users to limit speed until a fix is out, else someone is likely enough to get killed by ESP causing loss of control @>=125mph.

TMC mods please sticky this thread on the front page until then ...

PS: Have just searched TFF.de but find no mention of this subject ... if either of you have posted about it there then please link.
 
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electrifier

Member
Apr 5, 2019
12
31
Germany
What maybe happening is regenerative braking does not know that it can't handle the power at those speeds until it tries to.
Also absolutely a possibility that it has to do with the transient of mechanical/regen brakes. In the wet it would be much worse!

1) what was the state of charge?
2) how cold was it the night before?
State of charge approx 70%
It was about 8 deg C the night before. I had driven 150km at speed that day, I think the battery was warm. Pretty sure the regen was showing full availability on the speedo.

Just to confirm that I am in the possession of the aforementioned car, attached an image of the splash screen (as kindly requested to substantiate my post)
 

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SammichLover

Banned
Dec 8, 2018
2,618
1,542
Yup
Wow, so it looks like all M3s have the same problem then (and probably not just in Germany) ... what has Tesla said about this? ( @electrifier also)

Really there should be some official notification pushed to the in-car display warning all users to limit speed until a fix is out, else someone is likely enough to get killed by ESP causing loss of control @>=125mph.

TMC mods please sticky this thread on the front page until then ...

PS: Have just searched TFF.de but find no mention of this subject ... if either of you have posted about it there then please link.
Plus tweet this at Musk. :p That'll shake the house and get a patch out quick as it is possible.

Thanks to both of you for reporting this.

This probably is a regional limit for testing, we don't have much here in North America to try this stuff out in any way and Tesla is still a very North America centric company with all their Big Brains based here in the US, mostly in California.
 

electrifier

Member
Apr 5, 2019
12
31
Germany
While I still believe its an ESP/ABS problem, one other thing that has come to mind is aerodynamics. Around the year 2000 Audi launched the TT and there were 5 deaths before Audi acknowledged that it had to modify the car with a rear spoiler. The accidents were in similar cirumstances as the one I have described, driving fast around bends on German Autobahns.
Audi Offers TT Fix After 5 Deaths
 

22522

Active Member
Jun 6, 2016
1,736
3,328
Texas
While I still believe its an ESP/ABS problem, one other thing that has come to mind is aerodynamics. Around the year 2000 Audi launched the TT and there were 5 deaths before Audi acknowledged that it had to modify the car with a rear spoiler. The accidents were in similar cirumstances as the one I have described, driving fast around bends on German Autobahns.
Audi Offers TT Fix After 5 Deaths

I think aerodynamic forces could well be part of it. They all (lift and drag) go as velocity squared. I doubt the algorithm for the rear wheel ABS has it factored properly.

I have not seen the actual flow over the vehicle, but did see a picture of one prototype with dining room table leaf sized spoilers coming off the deck lid...

Screen Shot 2019-04-09 at 3.43.00 AM.png

Imgur
Screen Shot 2019-04-09 at 4.25.16 AM.png

Here is speculation:
1) Pressure forces on a car can be estimated by the "streamline curvature" method. This means if you look streamlines of the actual airflow, the flow curves toward low pressure - low pressure is why it bends.
2) For cars that close the wake on a horizontal line, headroom for rear passengers conflicts with low drag and a closed wake. Chrysler 200 was notoriously canceled for compromising rear seat passenger egress.

“'The 200 failed because somebody thought that the rear-seat entry point inside the 200 — which is our fault, by the way — is not up to snuff,' Marchionne said.
The problem: The slope of the roof crimps the entry portal."
Chrysler 200: Why This Car Has Been Called a Failure
Screen Shot 2019-04-09 at 4.12.49 AM.png


For the Model 3, different than the TT BTW, the steepest part of the pressure recovery region is pushed toward the back of the car to provide headroom. Even with the glass roof headroom and aero is a struggle.

3) If the pressure recovery region is too steep, attached flow can be intermittent. Bigger spoilers can suck down the flow to make attached flow less intermittent. "Spoiler" may be used incorrectly here... Rather let's say a fence that keeps separated/reverse flow from creeping forward off the rear face of the car. See picture of table leaf above. Dagger boards sailboats sometimes have special rear edge treatments to avoid flutter and humming - rear edge treatments are known to help stabilize the flow.

Since at high speeds the forces are high, intermittent aerodynamic lift could mess with the electronic stability control algorithm. As the car dives or rotates forward on initial braking the flow may more completely attach, changing lift suddenly. In other words, initiating braking changes the angle of attack.

In other words, you might be onto something!
Thanks for speaking up to get this resolved quickly.

I like the idea of more downforce back there by using a real spoiler - even it hurts range a bit.
 
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OPRCE

Member
Jun 16, 2018
860
768
Bern, CH
Just to confirm that I am in the possession of the aforementioned car, attached an image of the splash screen (as kindly requested to substantiate my post)

Thanks for that photo, electrifier, exactly as requested per PM to help further authenticate your reporting for anyone perhaps with lingering doubt.

Please also link here to your report on TFF when it is published.

Any word from Tesla on this issue?
 

Realist

Member
Jun 10, 2013
321
80
Germany
There are no issues with lift and downforce.

The car is stable under throttle but ABS kicks in too early under braking in fast corners. Therefore your braking distance is lengthened.

I think the car has never been tested properly at these speeds. We are talking about 250kph corners. Unthinkable in the US, but reality in Germany.

It's basically a software problem and it mainly has to do with the setup of the ABS/ESP.
 

Electric Dream

Pilots the Millennium Milkfloat
Jul 21, 2016
1,683
2,759
UK
There are several test grounds in N. America. I'd be very surprised if high speed stability & emergency braking in fast curves hasn't been tested.

It's difficult to quantify what's being described without at least having a video clip, but even then you really need data logging to fully understand what might be happening.

This could be a particular combination of factors not many drivers have come across yet. Tyre pressures, tyre type, speed, road surface, cross winds etc. etc. etc.

Let's not forget there have now been at least two dedicated Tesla track days organised and at least one reasonably quick lap around the Nordschleif in the public domain and nothing unusual has been reported from those drivers.

The other thing to bear in mind is that hard braking at high speed with any amount of steering lock on is fundamentally going to unsettle any car and should be avoided at all costs regardless of how good the electronic driver aids are. I've been a passenger in more than one 4WD Porsche with all the fancy driver aids turned on and we still ended up on the grass because the driver didn't appreciate that the laws of physics are unbreakable.
 

OPRCE

Member
Jun 16, 2018
860
768
Bern, CH
There are no issues with lift and downforce.

The car is stable under throttle but ABS kicks in too early under braking in fast corners. Therefore your braking distance is lengthened.

I think the car has never been tested properly at these speeds. We are talking about 250kph corners. Unthinkable in the US, but reality in Germany.

It's basically a software problem and it mainly has to do with the setup of the ABS/ESP.

Please check your PMs regarding authentication photo, cheers.
 

TSLA Pilot

Active Member
Mar 12, 2013
1,736
2,388
United States
Based in Germany I am new to the "Tesla World". I took delivery of the M3 last week.

I guess with first M3s coming to Germany only last month, there is limited high speed handling experience with the car on "normal roads". Nevertheless, I would like to find out if anyone has had the same problem as me.

Yesterday I was driving at max speed 233kmh for an extended stretch (German Autobahn), the handling through long radius bends and slight undulations was very firm and reassuring. The M3s high speed handling very positively surprised me and is absolutely up there with a high end Audi/BMWs etc (which are made for high speed and the M3 I guess isnt). So far so good.

Later I was travelling at about 200kmh through another long radius bend (without undulations) and had to slow down due to traffic. As I touched the brakes at roughly 50% max brake power, the car suddendly got completely unsettled, ABS/ESP on all 4 wheels set off one after the other trying to stabilize the car only making it worse. The car all of a sudden felt like riding on soap! This ABS/ESP situation lasted for - what felt a few seconds - it was probably 2s? This is not a speed at whicih you want to crash out! Shocked of the experience I then reduced speed and a similar situation happened a few minutes later at around 160kmh (Darwin Award worthy?). For the record, I am stating below the conditions at the time.

After this incidence my confidence in the handling plummeted, as I don't know what awaits me next! Most disconcerning is that the car otherwise handles and brakes (in a straight line, even from high speed at 100% brake power) fine, so it would appear to be an electronic malfunction only under certain conditions.

I can only warn you not to "try this at home" as it was very seriously dangerous, but I would be appreciative of any advice or experience any of you may have had.

Car: Model 3 AWD LR 19"
Payload: only 70kg driver
Software: 2019.8.3 da116a6
Temperature: 14 degC
Road surface: Concrete
Dampness: Dry (warm afternoon)
Tyres: "summer tyres"
Tyre pressure: 2.9bar
Light: daylight
Road: Germany, A20 between Lübeck and Bad Segeberg, left hand curve near Mönkhagen travelling on left lane.

We were one of the early Model S buyers and reported a serious safety concern years ago--an odd software glitch which had the car remain at WOT despite removal of one's foot from the accelerator (and no, the floor mat was well clear). As a HF engineer by training, and a pilot by profession, this was a situation that I could handle, fortunately, so it happened to the right person, at the right time (open Interstate highway) so I had to some seconds to diagnose and react.

Fortunately, Tesla took me seriously and did a deep dive into the anomaly, which is impressive as about 99.9% of these situations are pedal misapplication/human error incidents.

Tesla zone rep called to advise me that yes, they had found an anomaly and software was upgraded OTA soon thereafter.

Tesla is a small company trying to save the planet. It is very likely they are unaware of this anomaly. I urgently suggest you contact your local service center and also leave a detailed write up, with "Escalation," on your Tesla webpage ASAP. Hopefully they'll go with you to this portion of the Autobahn and duplicate at slowly increasing speeds until they get to the bottom of it.

We have a planet to save and your report may save someone's life, and will also help Tesla immensely.

Thank you for your detailed and informative post.
 

22522

Active Member
Jun 6, 2016
1,736
3,328
Texas
There are no issues with lift and downforce.

The car is stable under throttle but ABS kicks in too early under braking in fast corners. Therefore your braking distance is lengthened.

I think the car has never been tested properly at these speeds. We are talking about 250kph corners. Unthinkable in the US, but reality in Germany.

It's basically a software problem and it mainly has to do with the setup of the ABS/ESP.

Does your performance 3 have a spoiler?
 
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Electric Dream

Pilots the Millennium Milkfloat
Jul 21, 2016
1,683
2,759
UK
Braking distance will be longer in a bend with or without driver aids because one or more of the tyres will be unloaded so there's not as much of a contact patch on the road or weight on those corners.

I think the question here may be whether the software is being over-cautious and not allowing enough braking to one or more wheels in this situation, or maybe the ABS is triggering too early which will compound the problem.

Either way, what need to happen is as said above. A test driver needs to duplicate the conditions described to see if they can reproduce the issue.

I also note that there's no mention of anyone losing control of the car in these cases. Just that they felt the car was braking less or was less stable. The electronics could be doing all sorts of things to help the driver avoid losing control which the driver may not like the feel of, but at least it prevented a complete loss.
 
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electrifier

Member
Apr 5, 2019
12
31
Germany
Thanks for all your input!

I also note that there's no mention of anyone losing control of the car in these cases. Just that they felt the car was braking less or was less stable.
I must emphasize the following - the conditions were optimal for keeping control of the car namely:
-it was dry
-it was daylight
-I was concentrated (no distractions and only started driving 20min earlier)
-I have driven many different cars in the same situation (in fact several in the same curve) and consider myself an above average experienced and able driver
-I was only doing moderate braking (far from full lock)
-I was driving in an anticipating way and so did the people around me
-it was only a moderate bend
-there was no camber in the road (lifting the car)
-there was very little wind

-> as it was, the situation was already dangerous. Any or several of the above being more adverse and I could have been off the road.

The other thing to bear in mind is that hard braking at high speed with any amount of steering lock on is fundamentally going to unsettle any car and should be avoided at all costs regardless of how good the electronic driver aids are.
I fully appreciate that but the M3s reaction was completely unexpected and sporadic and unilke anything I have ever driven.
The reality is that on an Autobahn you have to brake in bends under certain circumstances, ideal or not.

Hopefully they'll go with you to this portion of the Autobahn and duplicate at slowly increasing speeds until they get to the bottom of it.
I really hope not. I don't want to be near when this is being replicated, not at those speeds! I can only urge nobody to try and replicate the setup on a public road!

leave a detailed write up, with "Escalation," on your Tesla webpage ASAP
What do you mean by this? Issue is raised with Tesla, awaiting their reply.
 
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TSLA Pilot

Active Member
Mar 12, 2013
1,736
2,388
United States
Thanks for all your input!


I must emphasize the following - the conditions were optimal for keeping control of the car namely:
-it was dry
-it was daylight
-I was concentrated (no distractions and only started driving 20min earlier)
-I have driven many different cars in the same situation (in fact several in the same curve) and consider myself an above average experienced and able driver
-I was only doing moderate braking (far from full lock)
-I was driving in an anticipating way and so did the people around me
-it was only a moderate bend
-there was no camber in the road (lifting the car)
-there was very little wind

-> as it was, the situation was already dangerous. Any or several of the above being more adverse and I could have been off the road.


I fully appreciate that but the M3s reaction was completely unexpected and sporadic and unilke anything I have ever driven.
The reality is that on an Autobahn you have to brake in bends under certain circumstances, ideal or not.


I really hope not. I don't want to be near when this is being replicated, not at those speeds! I can only urge nobody to try and replicate the setup on a public road!


What do you mean by this? Issue is raised with Tesla, awaiting their reply.

Tesla used to have an "Escalate this issue" or equivalent on the owner's home page; no longer see it however.

Please keep us posted on how Tesla responds. Someone is likely to be seriously injured or die if this issue isn't limited to just your specific car, which would be unlikely . . . .

(Also, pretty much by definition, any licensed driver in Germany is likely in the Top 5% of US drivers by way of education, training, and actual expertise in high-speed vehicle operation:)
 
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