So I finished up the front right wheel bearing replacement and all control arms and tie rod this morning. I took it out for a test drive and the abs is acting funny. When I first pulled out of the driveway I sped down the side street and went about 50-60% on the brakes and I got a small flutter and could feel the abs kick in, did't feel like it was full on abs just a little bit...kept driving and It continued...the brakes feel like they should, everythings quiet (no odd noises). Could I have damaged the abs sensor??? Does the computer have to relearn the markings on the axle? What do you guys think?

I was hoping to do both sides but I'm officially done for the weekend...football time. But next week the other side will get done and I'll probably have to schedule an alignment not long after that.

Thanks for your input

Oh and it's a 1997 audi a4 1.8tq 5 speed

 

Assume there is no ABS light on, yes?
Generally an unwarranted ABS activation is from the sensor not being seated fully (air gap to large) or the tone ring has cracked or is damaged or loose..........etc.

Still could be the sensor itself also. Before replacing it though, look very carefully at the tone ring on the CV joint. Inspect the entire circumference, check that it's tight on the joint and that it's not damaged in any way. It doesn't take much to "fool" the ABS module into thinking the wheel is starting to lock.
Also make sure the air gap isn't too big. Not sure if there's a spec but the sensor should be fairly close to the tone ring. Depnding on where you live, rust can build up between the sensor and knuckle, pushing the sensor out and making the air gap too big.

 

Sometimes they get dirty and just cleaning it can fix it. Same thing happened to me when I did a control arm. Remove sensor, clean it, if you have air, you can blow out the bore where it mounts.

 

I was just thinking....I sprayed all the bolts/bushings with pb blaster and that included the abs sensor. I'm thinking this could be causing the issues. I never actually removed the sensor and in cleaning the bearing housing and surrounding area I'm sure there was some debris that got to the sensor. I'll try cleaning it later this week...I'm sure that will fix it and I'll get back to you with the results after.

 

pull it out- if it was really rusty in that area then lots of metal flakes get stuck to the magnet causing it not to pick up the ring. Only one bolt - easy peazy.

 

UPDATE:

So I pulled the sensor this morning and it did have some rust/debris on the end of the sensor. I was able to remove the sensor and retaining clip without damage. (When I did the rears years ago it was so rusted/clogged up I ended up destroying the sensor) Anyways, I cleaned everything up and reinstalled and took it for a test drive...works like a charm, no abs pumping or odd petal feel.

Thank You

I also added a half bottle of seafoam to the gas tank (about 1/3 tank, always run 91) and the other half to the intake, let it sit for 15 min and fired it up...super smoke show...(this was before the test drive), test drive burnt most of the seafoam off and it seems to of helped with general running, Idle's a bit smoother and didn't get any misses or engine codes. I'll see how long it lasts

I have another post about the 02 sensor which is coming Tuesday. But this seems to of helped...maybe it cleaned a bit of junk out of the cat.