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

[bluegrassvroom]

i've had a few odd electronics/pcm 'quirks' - but nothing that scares me. Even when the PCM reboots - my car is safe and drivable

however - i'm scared to death of my car. in the rain.

before posting this - i've been reading the boards and google - and i haven't seen anything similar reported or experienced. One person DID mention: SPONGY BRAKES AFTER GETTING A CAR WASH - AFTER ONE GOOD (AND LOUD/SQUEAKY) STOP AFTER THE CAR WASH - THEY WERE FINE AFTERWARDS. This person used the best term - 'spongy brakes' - that discussion kind of ended with - BAH - IT'S A PORSCHE "FEATURE" WITH THE HIGH-END BRAKES. ONE GOOD STOP AND YOU'RE FINE, NO WORRIES

"Gogs" in this post https://www.taycanforum.com/forum/threads/strange-braking-issue.4818/
said : When braking the brake seems to work then it sinks a further few inches without any braking torque. If you push further then it seem to slow down. But not as fast as normal.

His post kind of went nowhere- i don't think the others were experiencing the same thing.

so i was hesitant to say anything. I thought - maybe this is normal.

i'm driving a 2021 4s with PSCB. i notice this ALMOST EVERY TIME I'M DRIVING IN MODERATE OR HEAVY RAIN. Not not every stop in heavy/moderate rain. If i'm running errands in that weather- i imagine i'll use brake pedal 6-8 times each way of a trip - this will happen maybe 1 of 7 brake applications

my brakes don't work. well, that is. My brakes don't work well in the heavy or moderate rain. For some stops

i get a weird/odd pressure from the brake pedal. I've driven this enough to know what the feedback pressure from that left pedal should be - and it's like it goes limp. Best analogy i have- imagine in an older car - if the bake line were cut, you'd have no pressure when you push in the brake pedal (i imagine??). I won't say my brakes aren't gripping (and yes, yes, yes, i know, blah blah blah majority of stopping is regenerative blah blah blah) - sorry- i won't say my brakes aren't gripping - it's more like my pedal goes bad and isn't telling them to

I HAVE TO LAY ON MY BRAKES SO HARD, THAT MANY TIMES, THE GREEN HOLD IS LIT ON MY DASH AFTER ATTEMPTING TO STOP. (if you didn't know - if you're stopped, and then press the brake pedal even harder, a green HOLD lights on the dash, you can take your foot off the pedal, and your car will sit there and not slowly inch forward)

And i'm not a 16 year old boy jamming the pedals all the way when i drive - i'm driving the same stop/start speeds as the other cars around me. normally - i apply 10-20% brake pedal - no one should EVER press the brake pedal hard enough to have the HOLD light come on after a stop

It was so bad once - my car wouldn't stop coming up to a light. i was going to hit the car in front of me, thank goodness, the turn lane was empty so i got into it and the car DID stop before the light. My kid asked where we were going (knowing it wasn't the way home) and i made up some excuse that sounded better than "daddy almost killed you in this death trap"
Two reasons i'm hesitant to take it in:

1) i'm 90 minutes from the dealer
2) it's so un-reproducable that i'm SURE they won't experience exactly what i am when this happens. then they'll think i'm exaggerating and not take it seriously.

ok, that and my kid is away on active duty, and i can drive her car in the rain. Says something abut this car when i'd rather drive a '18 Nissan Kicks on wet days....

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[smohr33]

How do you expect a potential problem to be solved without diagnosis?

If your car really has an issue, state your case clearly to your SA, and let them troubleshoot. This is what service departments do. Ask to ride with a tech if you have to.

My dealer had my car for weeks before they diagnosed a bad motor. They drove it numerous times to diagnose.

If you don't want to take the 90 minute drive to the dealer - then you're stuck with the brakes you have.

 

[02bluesuperroo]

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/

 

[RaidenTsao]

I have a similar experience with my Audi e-tron. I have no idea why. I suspect the system is confused between regen and mechanical brake. In all cases, I don't hear mechanical brakes engaged. And regen (green bar) is not activated (engine too cold or SOC too high)

 

[bluegrassvroom]

thanks for replies. as i was typing, @smohr33 , i realized how much a dumb@$$ i was for saying I'M AFRAID I'LL DIE and not taking it in.... Thanks for calling me out on it - i needed that

i have made my sales guy and the service department aware of the issue (i had to pull over practically in tears i was so scared one day- about a month ago) and they're researching and looking into it- nothing popped immediately.

my plan was to look for a week with multiple rain days and try and get it to them then and let them hold on to it for an extended time. Trouble is - never get more than a day of rain and sometimes in advance it's hard to tell if it'll be a sprinkle or a Noah-like deluge

@Archimedes - never in the dry. Maybe once in the snow but i was accidentally sold summer tires instead of documented All Seasons ($50 if you can figure that out) so i'm not driving it in the snow currently.

@02bluesuperroo - yes, PSCB - the very first post sounded like mine - but unlike some of the responses - it's not simply something to get used to. imagine having to run off the road or quickly change lanes because your car is taking four times longer to stop. That's not something i can put up with

OK - Mind's made up after typing that last line - i WILL take it in. it's a safety issue at this point and i'll schedule something. I'm getting a K40 installed (near the dealership) end of Feb so i'll try to schedule it all for one drop off - and update ya'll

if anyone else has anything to add please keep the replies coming

 

[JimBob]

Have you referred to the section on Brakes and water film on brake discs in the owners manual? I think its page 61. This paragraph appears to apply to all 3 brake types. Is your problem worse than this?

I have had this occur after washing the car or occasionally in heavy rain as indicated or the car has been idle for a long period of time.

 

[Fish Fingers]

You defo need to take it in. Don't mess about with tyres and brakes.

I don't think normal braking ever gets close to turning the green HOLD light on for me.
It's never done it even under hard braking.

I have the standard brakes on mine.

But I'm sure I have seen it mentioned on here when speccing the car that the 'higher spec' brakes are OTT for the Taycan with its regen and are uneccesary?

 

[bluegrassvroom]

Have you referred to the section on Brakes and water film on brake discs in the owners manual? I think its page 61. This paragraph appears to apply to all 3 brake types. Is your problem worse than this?

I have had this occur after washing the car or occasionally in heavy rain as indicated or the car has been idle for a long period of time.

from the manual - exactly where you said (that's kind of scary, no??)
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.
- 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 behind you is not affected.


Yeah- thanks, i appreciate that. This entry to me implies it's SLIGHTLY decreased. Not decreased to the extent where you're running on the shoulder to avoid rear ending the car in front of you and frantically searching how to apply the emergency brake if it happens again.

The weirdest part to me - the brake pedal seems to be what's not working, not the mechanical friction to slow you down part... The pedal has to be pushed much much further than normal, and it's not giving the same resistance it normally does.

I have not tried "drying" the brakes by applying them at intervals. I can attempt that in the next rain. If i never post again, this didn't work and i died.

but for real - in the heavy rain if you're driving running errands for an hour or two - what does it want us to do- pump the brakes every 30 seconds whether you need to slow down or not? I'm not even kidding. what does this mean? ANd why is this a practical solution?

Upon typing all this - i'm actually remembering i have tried this unsuccessfully - i've tried to apply normally brake pressure - OH NO, NOT SLOWING DOWN, jam down the brake pedal - starts slowing a little - like 1/8 or 1/4 normal, i release and brake pedal and pump it again - getting same squishy/spongy/mushy response and poor performance and just 1/8-1/4 the normal stopping power

 

[JimBob]

As the dealer will likely point this part of the manual out to you, best to be prepared to make your case.

I have the iron brakes and I get it every time I wash the car. The first few times I almost smacked the car in front of me at a stop light so now do a hard braking when I leave the house. I also get it when the car sits for a weeks. I can see the oxidation on the rotors but it is cleared quickly with a hard braking.

Super wet weather is a bit more problematic, so I stretch out the distance between cars. I don't know what happens if you happen to be using ACC and how it handles this, if at all.

The problem is that with that paragraph in the owners manual and the traffic code, the chance of you avoiding being at fault is likely to be pretty remote.

 

[02bluesuperroo]

@02bluesuperroo - yes, PSCB - the very first post sounded like mine - but unlike some of the responses - it's not simply something to get used to. imagine having to run off the road or quickly change lanes because your car is taking four times longer to stop. That's not something i can put up with

Trust me, I know. One two occasions I have almost slammed into a curb while pulling into a parking space because I was traveling 5-10 MPH pulling in and I hit the brakes lightly to come to smooth stop and the car didn't stop. I then had to slam the brakes right before hitting the curb in order to stop in time.

Here is another thread discussing the issue so it's definitely been a problem noticed by a lot of people: https://www.taycanforum.com/forum/threads/brake-feel-after-amb5-not-good.6315/#post-89389

 

[RAHRCR]

from the manual - exactly where you said (that's kind of scary, no??)
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.
- 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 behind you is not affected.


Yeah- thanks, i appreciate that. This entry to me implies it's SLIGHTLY decreased. Not decreased to the extent where you're running on the shoulder to avoid rear ending the car in front of you and frantically searching how to apply the emergency brake if it happens again.

The weirdest part to me - the brake pedal seems to be what's not working, not the mechanical friction to slow you down part... The pedal has to be pushed much much further than normal, and it's not giving the same resistance it normally does.

I have not tried "drying" the brakes by applying them at intervals. I can attempt that in the next rain. If i never post again, this didn't work and i died.

but for real - in the heavy rain if you're driving running errands for an hour or two - what does it want us to do- pump the brakes every 30 seconds whether you need to slow down or not? I'm not even kidding. what does this mean? ANd why is this a practical solution?

Upon typing all this - i'm actually remembering i have tried this unsuccessfully - i've tried to apply normally brake pressure - OH NO, NOT SLOWING DOWN, jam down the brake pedal - starts slowing a little - like 1/8 or 1/4 normal, i release and brake pedal and pump it again - getting same squishy/spongy/mushy response and poor performance and just 1/8-1/4 the normal stopping power

I have had this occur 2 or 3 times in the past couple of years on my Pan ST with std brakes during heavy rain when getting off of the highway. Tough to argue that this is acceptable in any way but I have been able to prevent it now that I know that it can occur.

 

[tigerbalm]

I have PSCB. I live in Ireland. It rains. All the time. I don't have this.

 

[02bluesuperroo]

I have PSCB. I live in Ireland. It rains. All the time. I don't have this.

What model year car do you have? Did you have the AMB5 software update done?

 

[PanameraFrank]

PSCB shouldn't be the problem. It takes a LOT of braking to even engage mechanical brakes, almost all of the brake pedal travel is regen braking, this sounds more like an issue with regen working properly.

Take it in immediately and make it clear the brakes are effectively not working sometimes. They should take this quite seriously.

I drive in rain and snow all the time and braking has been 100% bulletproof amazing at all times.

 

[Windpower]

OP I would definitely take the car to the dealer for inspection, preferably during a week where rain is expected.

If its not raining, then drive it through a car wash (bad for the paint but might help show the problem without waiting for rain).

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