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

[bluegrassvroom]

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

2021 4S - got it in AUgust. I think. They had to hold onto it to do a large update right before i got it. if that update came out after then - then it hasn't been updated unless it's OTA

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[02bluesuperroo]

2021 4S - got it in AUgust. I think. They had to hold onto it to do a large update right before i got it. if that update came out after then - then it hasn't been updated unless it's OTA

Based on the timing, that's probably the AMB5 update. It was due to a recall that was issued on June 29th 2021. So you probably do have it which makes it potentially odd you didn't notice anything. Maybe it's too rainy there so you're just used to it.

 

[Jrkennedy37]

Does this occur in certain driving modes or is it all modes? I’ve noticed when regen is off that the brake pedal needs to be pushed quite a bit harder/further than when regen is on. I’ve grown used to it now but it caught me off guard the first few times I started driving and regen had not yet kicked in.

 

[Boss Hogg]

If you have Porsche Assistance in North America call them next time it rains and say you have a safety issue with the brakes and the car is unsafe to drive. If like in the UK, they'll recover your car to the dealer and arrange a rental while the issue is investigated/fixed.

 

[Boss Hogg]

Does this occur in certain driving modes or is it all modes? I’ve noticed when regen is off that the brake pedal needs to be pushed quite a bit harder/further than when regen is on. I’ve grown used to it now but it caught me off guard the first few times I started driving and regen had not yet kicked in.

I also notice this and it used to catch me out, especially on short trips where there is not enough time/braking for the car to switch to regen.

 

[atebit]

There is an “Excessive Brake Pedal Travel” bulletin. I had my car in for it. Ask your SA for it.

 

[DerekS]

Not only would I take it in immediately, I would call 1-800-PORSCHE and flatbed it in.

It sounds absolutely unsafe to drive.

 

[DerekS]

And FWIW I have PSCBs and have never felt anything but confidence from the brakes including emergency stops.

 

[Chris8536]

I had this happen too and in dry weather! In a hard stop the break suddenly pops forward and stops working. Scared the hell out of me. Jesus wtf is wrong with Porsche.

 

[Chris8536]

There is an “Excessive Brake Pedal Travel” bulletin. I had my car in for it. Ask your SA for it.

can you link to something?

 

[tigerbalm]

MY21

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

MY21 – delivered in Feb 2021. Yes, I do have all software updates/campaigns done on the car.

 

[logic]

I lol'ed reading the OP title.
And I learned how to stop my car from creeping forward (I really didn't know), thanks!

It only happened once after a long drive in wet conditions.
I switched to a more spirited drive and immediately needed the brakes (came in hot)... they did absolutely nothing (or not enough) for a slight moment but recovered quickly to normal. At high speeds you cover a lot of distance during that slight hesitation and that's a scary moment. It isn't any different from what I experienced in previous cars tho, in regards to having a wet braking surface. But the thing that catches you is that this car uses regen, and you may think you're "cleaning" the brakes but that's not the case. Only when you brake hard enough, it will switch to mechanical breaking. I need to take that into account and do a little brake check first.

But that's nothing compared to this. ?

 

[bluegrassvroom]

[snip]
But the thing that catches you is that this car uses regen, and you may think you're "cleaning" the brakes but that's not the case. Only when you brake hard enough, it will switch to mechanical breaking. I need to take that into account and do a little brake check first.

But that's nothing compared to this. ?

that's a great thought - thanks. pumping the breaks lightly doesn't 'clean' them because you're going regen brakes-off-regen brakes - off - regen brakes-off-regen brakes - off and not 'hitting' the mechanical brakes..... i never stopped to think about that and realize that

thought though - hadn't thought of this till now - mine wasn't in super fast conditions nor hard braking - mostly stop and go traffic (ok, maybe whatever's JUST ABOVE stop and go traffic - you know, with a bunch of cars at traffic light, accelerate to 35-45mph, another traffic light, slow down, repeat). i THOUGHT in those conditions, it was 100% regen brakes?

i wouldn't imagine regen brakes shouldn't be affected by conditions. IN my head - the resistance from the magnets and electric coils from the motor should work 100% of the time

maybe i'm using a LOT MORE mechanical braking than i realized

in most conditions- i feel like i'm not depressing the brake pedal more than 20%.

DOES ANYONE KNOW "WHEN" THE MECAHNICAL BRAKING KICKS IN? how to tell when you've gone beyond regen braking? I feel like, even in these circumstances, that little power/regen meter on my car never goes past, hmm... this professionally rendered mockup shows you what i'm thinking

see image uploaded - i feel like i hardly ever go past #1 on the regen meter - and i wouldn't think mechanical brakes come into play until #2 or further (you can choose this view on the dash - when you're using the motors, the meter starts at 12 o'clock and goes clockwise - the harder you accelerate, the further the POWER USAGE goes. when (regen) braking, it starts at 12 o'clock and goes counterclockwise. i don't know if i've EVER seen the regen meter go past 9 o'clock....

 

[JimBob]

If you do a search under Porsche Recuperation Management you can find some information on your questions. Not particularly detailed as to how it is actually implemented.

Here is an excerpt from their brochure.

 

[Benji_OOS]

I have noticed this once or twice after washing my car with the standard brakes. And also once experienced the low speed delay mentioned (I think also after washing or weather.)

What I like to do to ensure the disks are clean is to put the car in to Neutral while rolling and apply the brakes which prevents regen from activating so I know they are cleaning the disk for certain. Not ideal but it might be worthwhile to know of this method while dealing with your issue or waiting for diagnosis.

Ask your dealer to spray down the brakes before test drive to help create the problem without needing weather to be in your favor!

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