CharlieMac

I recently replaced my front and rear pads and rotors with some Drilled/slotted Adams rotors and EBC reds pads. Change went smooth but I have an extremely squishy brake pedal with a LOT of travel.

Now that I have explained my issue let me go into more detail, I have a 2011 US A8 that desperately needed new pads and rotors. I waited a long time past getting the ole "Brake Pads" warning to replace since I was ordering rotors
from Adams rotors and it took me a while to decide what I wanted and then to get the finished product. Prior to getting the parts I would occasionally get a soft brake pedal and then a ACC & Brake guard are not available warning.
I honestly figured I was getting it due to the state of my pads and rotors, the issue itself got worse and worse and pretty much happens all the time now. I replaced the equipment thinking it would fix the problem and it didn't.
At this point I went to the dealer and they said it was the ABS controller that needed to be replaced, $3k later the part is replaced and I still have the same issue.

To recap:
I have a lot of travel in the pedal, I still get the code.
I have new pads and rotors
I have a new ABS controller
Dealership said the bled the system so I "shouldn't" have any air in the lines.
Dealership said the vacuum was "great" so I don't appear to have any leaks.

Any ideas why I still have travel almost to the floor and I am still getting the ACC & Brake guard code?

I don't have my VAG scan on this comp, if you think it would be beneficial I can add.

Oh yea, The dealership has no clue why this is happening and has said that since I have "aftermarket brakes and pads" it could be the issue. I responded with "change to OEM but if the issue is still there then change back and don't charge me." Needless to say I got crickets from the dealership on that.

MP4.2+6.0

Questions: What is the full history of bleeding the system--for as long as you owned car? Did you bleed brakes when you did the brake work, or only the dealer later on? Did the long pedal movement arise gradually or quickly?

Offhand my guess is the issue is still around bleeding the system. Hence the questions there. In particular, if the system is ever run dry of fluid, it can be really, really hard to get it air free again, specifically around the ABS hydraulic unit. From having done it once, it takes many bleeding cycles to purge the air. It can happen simply by not watching the fluid level carefully while bleeding and it goes too low on one of the two reservoir sides. There used to be a way you could cycle the ABS unit with VCDS to assist in getting air out of it, but I haven't seen that mentioned in many years now. To be clear, for the ABS unit I am referring to the hydraulic part with the brake lines, not the controller you mention that screws to the side of it. The controller can typically be changed without opening the brake lines at all.

BTAudi

I agree. Brakes probably need bled. If fluid is older than 2 years just do a good flush and you should get all the air out.

odgreenboy

Also check that the retaining clips and pads are all properly seated.

CharlieMac

The full history of bleeding is unknown to me, I bought the car 2.5 years ago with 32k miles on it and up until about 60 days ago I never had any issues with the brakes. The squishy / long travel happened all of a sudden but normally after restart it would go away and not happen for a while and honestly not very often (maybe once a week) and other then that the brakes felt perfect. I can also only say that I Never check the fluid level myself but my car is in for service regularly and the dealership has never noted a Low fluid level. I have thought the very same thing (leak or air in the lines) with the travel and squishy pedal, but the dealership has said they "thoroughly bled the brakes with their vacuum tool".

rally

what he said. I had a soft pedal due to one side of a clip being improperly positioned. Dealer missed it several times.
clip repositioned and pedal returned to normal.

CharlieMac

I will see about checking the clips but I would assume if it was a clip issue it wouldn't have happened before the brake job as well. Right now the dealership thinks the ABS controller they got from Audi is a bad part and is ordering a new one. Lets see what they find.

MP4.2+6.0

FWIW, I'm not particularly buying the ABS controller. Even with that dead you should have full mechanical + hydraulic brakes, with the (vacuum) power assist. ABS hydraulic unit, maybe, master cylinder, maybe. Vacuum booster unit, maybe.

gk1

Master cylinder would be my guess.

odgreenboy

I went through all of this a few months ago and the car was in the shop for over 2 months.
OEM Rotors with EBC stuff. Issue started with in 1000 miles of installation.

Delear replaced brake booster, master cylinder, ABS control module, multiple bleeds software flash......blamed EBC....blamed indy that did the work. In the end they called audi engineering for help.
When they took pictures of the installation and sent them to the engineers it was clear that step one of the trouble shooting- condition and security (proper seating) was not completed. I had one retaining clip stuck under the pad.
I have photos some where and will post them once found.

If you have not double checked this is by far the easiest and cheapest cause to fix. I'm lucky to have an aftermarket warrantee from USAA that covered ~ $10,000 in bills.