I searched, I didn't get specific results.
I checked the service manual, and am still a bit confused.
Just fyi, so you don't attempt to flame me. Thanks.

While driving my s4 GXL, I have been having erratic, poor braking. Sometimes it is after some hard driving, sometimes it is casual driving not exceeding even 3k rpms. It is very random. This erratic, poor braking is due to a very stiff feeling pedal. I have never needed to pump the brakes, but when this pathetic braking problem occurs, it feels as if I have been pumping the brakes and caused a stiff pedal. I have to apply strong pressure with my foot, and it still feels like it doesn't want to stop.
Note: I've had no braking problems since I bought the car in the summer until this cold weather. Coincidence?

I read that it could possibly be a check valve. If so, where is that, and how do I correct it?
A bad master cylinder will cause the pedal to drop, so it is not that, correct?


Thank you..

Scott
RVA

 

Anyone?

 

Any support? I'd like to be able to brake safely.

 

Sounds like maybe a dead vacuum booster, does it feel the same as if you had the car off? Pedal feel..

 

IGNORE. (double post)

 

Yes, it feels very similar. I need to get this handled asap! How would I go about determining if its a dead vac booster?

 

i would first check the vacuum lines on the vac booster for cracks, bad connections etc. I would do a general vacuum check on the engine.

Then I would trouble shoot the vacuum booster as per the FSM. Find that in the archive section.

Good luck.

 

I read it over in the FSM. I didn't see how to determine if it was good or not. I just saw where it basically says, "Replace if damaged" or whatever.

Maybe I missed something?