periodic "spongy" brakes. that don't stop. if i die please have my family sue Porsche

[sailboat310]

After leaving the Taycan overnight at work, I tried it again today and voila, after the first hard break with spongy pedal, the car seems to have recalibrated. The brakes feel a little firmer than usual, but no groaning or spongy feel. The cutover from the regen to mechanical brake seems almost unnoticeable.

Now that the wet weather has abated with fairly dry roads, the problem seems to have gone away.... go figure. Now how to replicate this for the service department.....

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[DerekS]

I was digging through the manual and found something interesting:

In heavy rain, when driving through water or after leaving a car wash, the braking action may be delayed and increased foot pressure may be required.

• Ensure that the temperature of the vehicle is between approx. -20 °C and +30 °C during the charging process.
• Check the brakes after washing the vehicle.
• For this reason, keep further back from the vehicle in front and “dry” the brakes by applying them at intervals. Make sure that the traffic be- hind you is not affected.

 

[IBZman]

I was digging through the manual and found something interesting:

In heavy rain, when driving through water or after leaving a car wash, the braking action may be delayed and increased foot pressure may be required.

• Ensure that the temperature of the vehicle is between approx. -20 °C and +30 °C during the charging process.
• Check the brakes after washing the vehicle.
• For this reason, keep further back from the vehicle in front and “dry” the brakes by applying them at intervals. Make sure that the traffic be- hind you is not affected.

My OPC quoted this reference when it was last in for this issue. Unfortunately, all this shows is they are aware of this issue! Sadly, I don’t drive my Taycan they way I won’t to… I simply cannot trust it to stop!

 

[sailboat310]

Yes, this is what the service rep told me, but it didn't do anything to help yesterday.

Today, that worked, but ALL DAY yesterday, nothing would get rid of the spongy brake feeling. The regen braking worked fine, but when it cut over to the mechanical at low speed, the brake pedal would have to be depressed almost to the bottom which would then lead to it shuddering/groaning suddenly to a halt.

I tried to replicate it today with spraying an immense amount of water on the brakes and driving through the puddles I made, but it doesn't come back.....

The dealer says if it happens again, they will provide me a loaner Taycan until one of their senior engineers come by end of January. Guess I'll be driving the truck on wet days until then. Don't want to unnecessarily risk for it to happen again.

 

[DerekS]

Question. How often do you charge?

I was trying to find it in the manual but I swear I read somewhere that the brakes are recalibrated during charging.

 

[bsclywilly]

Question. How often do you charge?

I was trying to find it in the manual but I swear I read somewhere that the brakes are recalibrated during charging.

The brake stiffness learning function is described in the TSB
https://static.nhtsa.gov/odi/tsbs/2022/MC-10217260-0001.pdf

Basically everytime the vehicle is charging or 200-300km.

The ultimate recommendation of the TSB is to do a brake bleed after some software checks. Then replacement of brake booster, then master cylinder. Anyone with this issue should insist on a brake bleed as a first step to troubleshooting.

 

[WasserGKuehlt]

The brake stiffness learning function is described in the TSB
https://static.nhtsa.gov/odi/tsbs/2022/MC-10217260-0001.pdf

Basically everytime the vehicle is charging or 200-300km.

Thanks for sharing, that explains quite a lot of this thread (and the underlying functionality is very cool on its own).

 

[AboveTheLaw]

I have had the same issue. Took the car in a few months ago and they did the work suggested in the service bulletin. The issue persists when the brakes get wet and there is a significant loss in braking ability. Requires the brake pedal to be floored to have any stopping power.

Has anyone had an accident related to this issue? Please let me know. I am considering a class action lawsuit.

 

[bluegrassvroom]

I have had the same issue. Took the car in a few months ago and they did the work suggested in the service bulletin. The issue persists when the brakes get wet and there is a significant loss in braking ability. Requires the brake pedal to be floored to have any stopping power.

Has anyone had an accident related to this issue? Please let me know. I am considering a class action lawsuit.

no wreck yet - but i'm compiling and taking the info to the NHTSA. Porsche NA was looking into this and deemed it working as designed. Apologies to you guys who might get your cars recalled. I know i should have threatened this before they went Public....

Last weekend was the first torrential downpour since i had a major service appointment 2-3 months ago, and it did the same thing. I just haven't been driving it in the rain, been taking my wife's Q8 when practical and possible

 

[bluegrassvroom]

Submitted to the NHTSA - i'll let ya'll know how it progresses. Very little info to submit (per their site)- difficult to summarize this in 2000 characters (first take was 4700) and no way to upload videos, only images. Hopefully that's just the doorkeeper and next round we can share more information

 

[bluegrassvroom]

I uploaded this video to another thread on this site and thought i'd add it here

i went back and watched some videos - here's a truncated one - showing me stopping halfway into a road when going 6-7 miles an hour. if the car stops 10 feet long at 6-7 miles an hour, imagine what it'd do going 30 or 40 or 50 mph when this happens

I didn't realize NHTSA complaints were public and search-able - and some other Forum posters found mine and commented heavily before i saw the thread and posted supporting information

https://www.taycanforum.com/forum/t...onditions-nhtsa-complaint-march-2-2023.15067/

 

[DerekS]

I uploaded this video to another thread on this site and thought i'd add it here

i went back and watched some videos - here's a truncated one - showing me stopping halfway into a road when going 6-7 miles an hour. if the car stops 10 feet long at 6-7 miles an hour, imagine what it'd do going 30 or 40 or 50 mph when this happens

I didn't realize NHTSA complaints were public and search-able - and some other Forum posters found mine and commented heavily before i saw the thread and posted supporting information

https://www.taycanforum.com/forum/t...onditions-nhtsa-complaint-march-2-2023.15067/

You should get someone else to hold the cam. It's impossible to make any assessments about what is going on from this.

 

[Redhot2474]

Ive

You're not the only one. I've noticed this too and there was another thread about it on here a couple of weeks ago. Do you have PSCB?

https://www.taycanforum.com/forum/threads/pscb-during-rain-no-friction.8449/

I’ve noticed this after a car wash for sure , spongy breaks , yep

 

[bluegrassvroom]

You should get someone else to hold the cam. It's impossible to make any assessments about what is going on from this.

I'm not denying that. But to me - it's clear that a) the regen isn't kicking on at all, and B) - the car stopped a half a car length into the road, when i was only going 6-7 mph.

one thing i could never get the video to show, whether i hold it or someone else did - is that pushing the brakes has zero resistance, it's like a 'dead pedal'

it's just not a condition that video really helps illustrate. if anyone has any ideas what i could video (myself or with help) to illustrate this not functioning correctly, i'm all ears. Honestly - what video what get the NHTSA to act, or media to respond, or Porsche to care?

I'm not going to be that guy who's spent millions to show how bad Tesla's AutoPilot can be in sone situations... As an aside - if you are unfamiliar - https://www.google.com/search?q=man+spent+millions+at+superbowl+to+show+tesla+autopilot

 

[Tooney]

@bluegrassvroom
I may have missed it in earlier posts. Have you done your braking test after driving through standing water with braking recuperation enabled? If so, do either of the two problems still occur:
--regen braking not occurring
--needing to floor the brake pedal to get mechanical brake to stop the car?
In other words, is driving with brake recuperation enabled a workaround for the problem?

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