Soft brake pedal and thinking about bleeding your brakes?

[Shug]

I have a soft brake pedal which was not improved by the recent front brake hose recall.

I wondered whether there might be air trapped in my ABS that would be difficult to flush and saw that PIWIS has a routine that assists by opening the ABS

The ARB0 recall for the brake hose replacement states to "bleed the brake system", however this may only be a front brake bleed.

The service procedure for bleeding the brakes (470107) it states:-

Bleed brakes in the normal way (in combination with bleeding device at the brake fluid reservoir and 2.0 bar pressure).

Additionally, if the hydraulic unit has been replaced and, after bleeding in the normal way (primary circuit), the brake pedal travel is excessive, use the PIWIS Tester to bleed the brakes (secondary circuit)

It seems reasonable that if you have a long pedal, using the PIWIS to bleed the secondary circuit at the same time as the primary circuit would provide confidence that there is no air in your brake system.

PIWIS is not the friendliest system to use so decided to have a play around in the simulation mode as follows:-

Select Diagnostics

F12 simulation mode

Select your model

Select Brake booster then F12

Select F11 or F12 for VAL / No VAL

Switch to the Maintenance tab and select - Service bleeding and Maintenance repairs

F12

This guidance is then provided – F12 to continue

Select the wheel to bleed, then F8

F8 to continue

This is all done in simulation mode.

Plan to try it when plugged into the car next.

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[gtm]

In theory there is no reason why the entire brake system would be flushed when the brake hoses are replaced. Bleed the air from the front lines and done. Get a copy of workshop bulletin WPK0. There is a software update for the PSM module and specifics on how to "ventilate" the brake system. WPK0 might be US specific, but I doubt it, and was issued to address the brake pedal feel. You should be able to have the dealer perform the work under warranty. Made a huge improvement in my brake pedal consistency and feel.

 

[Draff1]

2023 Taycan CT4S - had the brake recall done in December. My brake feel before the recall was a not so solid 6 out of 10. Typical Taycan squishy but worakble pedal feel. Upon collecting the car post recall, the brake pedal feel went down to a 2 out of 10. Probably unsafe and definitely removed all fun from driving as there was a delayed braking reaction that caused alarm. Brought it back and they re-bled all lines and returned to previous crappy but acceptable levels. If anyone can diagnose this pedal feel to bring up to Porsche standards I’d love to know how to do it.

 

[gtm]

2023 Taycan CT4S - had the brake recall done in December. My brake feel before the recall was a not so solid 6 out of 10. Typical Taycan squishy but worakble pedal feel. Upon collecting the car post recall, the brake pedal feel went down to a 2 out of 10. Probably unsafe and definitely removed all fun from driving as there was a delayed braking reaction that caused alarm. Brought it back and they re-bled all lines and returned to previous crappy but acceptable levels. If anyone can diagnose this pedal feel to bring up to Porsche standards I’d love to know how to do it.

Something is not right. My car had very inconsistent braking to the point I would not let anyone else drive the car. I seriously doubt the brake hose recall did a thing, but I had WPK0 done at the same time (a software update to address the wonky pedal and a fairly involved bleeding/ventilating process). Night and day. Consistent engagement of the brakes, high pedal, barely ever feel any transition from regen to mechanical any more. If you have had WPK0 done then the system has not been "ventilated" (Porsche's term) properly.

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