S4s ABS porblem... any experts there

[bojangles]

Finally got my car picked up and it is really great..
I could go on but Ill save that for later.
Car has 19000 miles on it, and runs great.
'Cept the brakes...
OK, so I do hear a lot of ABS pump noise cycling often - not sure if this is normal.
If i push getly on the brake, the system kiks in and starts to push my foot back up , if I hold my foot steady the brakes just sorta self apply harder and harder. if I keep the light pressure the pedal lifts my foot up until it get to almost home position the itreleases adn my food drops down and the cycle continues
If I apply the brakes hard, the pedal is hard, then at some high braking pressure it suddenly releases and the pedal drops down and the car shakes then brakes again...

For sure something is wrong....
Id like to have an idea what I am up against before surrendering to a dealer..
comments appreciated
Bruce

[JK1]

Bruce,

What you describe does not sound too out of the ordinary other than the pump recycling which it will do, the question is if it is cycling too much.

It is normal for the pedal to push back against your foot pressure. I think the shaking that you are referring to sounds like the abs system engaging to prevent wheel lock. It is rather sudden and unsettling to the car. Not nearly as smooth as most of the later abs systems on other vehicles we are accustomed to. Hence the many complaints

Go to this link and perform the troubleshooting procedure for the Delco abs system and let us know what you find.


http://home.att.net/~aldridgec/TGP/brakes/powermaster.htm

I thought I had similar problems when I first got mine but after replacing the pads and turning the rotors (which it needed badly) I got used to the feel and have had no further problems.

Jim
95S4s

[Skerd]

The ABS on the 95.5 S4s is known to be terrible. My right front has a mind of its own.

[bojangles]

maybe I am spoiled from driving BMW, but even my 88 M5 has better feel and operation...
there must be something wrong..
I have driven GM cars from the 95 era and they are better too...
i guess I will muck around a bit and see what I can figure out...
Maybe a BMW Bosche ABS system can be fit in... heeh that would be very cool....

[bojangles]

ok, well 35 secs to charge the system,
and the pump cycles every second time I pump the brakes..
sometimes I get the red telltale light when I brake moderately.
This Am the yellow ABS light was on,,, care was wet from driving in the rain, - after driving one block then re-starting the ABS light stayed off...( could be english car syndrome)
still crappy brakes..

[karlfranz]

bojangles said:

ok, well 35 secs to charge the system, and the pump cycles every second time I pump the brakes.. sometimes I get the red telltale light when I brake moderately. This Am the yellow ABS light was on,,, care was wet from driving in the rain, - after driving one block then re-starting the ABS light stayed off...( could be english car syndrome) still crappy brakes..

This happens when the accumulator is starting to go and can no longer hold proper pressure. The same thing is starting to happen to my car so I will be replacing the accumulator as well. And yes, I agree with others: the ABS system in the S4s sucks!