Resolved - Braking Issue/PSM Failure, with Video

[WasserGKuehlt]

Copy. That.

Seriously neat exemplar. Yours?
Also, looks deceptively simple. ?

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[dtich]

Haha, no not mine, just internetted. I wouldn't want to change valves on that sucker.

 

[DynamoCappo]

https://newsroom.porsche.com/en/202...ke-force-distribution-recuperation-30953.html

Seeing the graphs here and reading it, I get the idea a bit more, but honestly, somehow it feels maybe a little too complicated for a braking system. Really, really relies on this calibration session and realtime calculations to make brake feel smooth and precise.

It also goes against how I see myself using my Taycan. I like to keep it nearer the top end of the charge so that, should I have to undertake longer journies that are unexepected - say being called out to a meeting during the day, I'm not burdened with a stop along the way due to range.

My understanding was that that was the mindset for EV useage and you didn't run it nearly dry like an ICE car where you can easily stop to refuel.

 

[irrelevant]

Latest update…brake system has been bled, and advisor says brake pedal is firm again. They believe the brake booster is faulty. My understanding is they think it may be cycling rapidly, causing aeration of some of the brake fluid.

The current plan is to remove and replace the brake booster. No information yet on how long it will take to get a replacement.

While I appreciate them providing the loaner car, I’m pretty much fed up with the Macan. I think I’ll leave it in the garage, and drive the Corvette instead.

 

[dtich]

It also goes against how I see myself using my Taycan. I like to keep it nearer the top end of the charge so that, should I have to undertake longer journies that are unexepected - say being called out to a meeting during the day, I'm not burdened with a stop along the way due to range.

My understanding was that that was the mindset for EV useage and you didn't run it nearly dry like an ICE car where you can easily stop to refuel.

The Tao of Lithium Ion is: Never get to Empty, Never stay at Full.

So, charge with 20-30% left in, and charge to 80-85 when it's convenient, and if you have to charge to 100, never let it sit there, start discharging soon. Li batteries like to sit around 50%. They can stay there for a LONG time without adversely affecting charge capability. Fast charging, quick and deep discharging, sitting at full or empty, is what it doesn't like. And it hates heat and eschews cold. Quite finicky really .

But, keep it in its happy place for the most part, and it will live a long and attention-free life.

 

[DynamoCappo]

And it hates heat and eschews cold. Quite finicky really ..

Sounds like the wife...

 

[irrelevant]

After ten days in the shop, our Taycan was returned this morning with a new brake booster and freshly-bled brakes. The car is stopping normally now, without the spongy brake pedal or “braying goat” noise when coming to a stop as it transitioned from regenerative braking to friction brakes.

 

[jcg]

Excellent! thank you for the update

 

[jvincent]

This past weekend I had the "opportunity" to charge overnight from below 20%SoC to 80ish. The next day the brake pedal felt amazing - consistent throughout, so much so that I couldn't help myself and did several full stops.

My brake feel has been all over the place lately. I usually keep my battery pack between 25 and 65% (I really don't need the range and why not pamper the battery). Read your post and charged 7-85% last night. Went for a drive this morning and the first results are positive; the nice, firm, uniform brake pedal feeling has returned. Thanks!

 

[Jonnysevel1]

I had the same problem on my 2023 Taycan 4S. Wen tiinto shop and they found a service bulletin that was for brake pedal travel. it required bleeding the brakes and then charging the car to recalibrate. It WORKED....for 3 weeks...then the spongy feel and "groaning" noise returned. Porsche is now saying that they want to replace the PSM. So we wait for the part from Germany....hopefully not too long.

Interestingly enough, my 2021 Taycan 4S has never experienced any of these braking issues. Brakes have been great for 12,000 miles and 2 years...

waiting to see what happens.

 

[irrelevant]

I had the same problem on my 2023 Taycan 4S. Wen tiinto shop and they found a service bulletin that was for brake pedal travel. it required bleeding the brakes and then charging the car to recalibrate. It WORKED....for 3 weeks...then the spongy feel and "groaning" noise returned. Porsche is now saying that they want to replace the PSM. So we wait for the part from Germany....hopefully not too long.

Interestingly enough, my 2021 Taycan 4S has never experienced any of these braking issues. Brakes have been great for 12,000 miles and 2 years...

waiting to see what happens.

I'm sorry to read this. Best wishes for a speedy resolution.

The fault code "stored in the PSM" for ours was PP05FF00. According to the service report, the "PSM Hydraulic Unit" was replaced, and the brake system re-bled. 700 miles later, the problem hasn't returned...though that's admittedly not many miles to draw a solid conclusion from.

 

[Jonnysevel1]

Actually that is good news to me!! I am so happy to hear that 700 miles and no recurrence. Fingers crossed the part gets in quickly.

 

[Chuck J]

That is very good information. Can I ask if you found less creeking whe you had the regen on?

Chuck j
2020 4S

 

[irrelevant]

That is very good information. Can I ask if you found less creeking whe you had the regen on?

Chuck j
2020 4S

There would be no change expected, because the issue occurs as the Taycan transitions from regen to friction braking, which occurs around 7 mph during normal deceleration. It was the brake booster servo cycling that was causing the noise, which also was aerating the brake fluid, leading to a soft brake pedal.

 

[Chuck J]

There would be no change expected, because the issue occurs as the Taycan transitions from regen to friction braking, which occurs around 7 mph during normal deceleration. It was the brake booster servo cycling that was causing the noise, which also was aerating the brake fluid, leading to a soft brake pedal.

You hit it right on the button.

Thanks

Chuck J

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