ABS Woes!!

[A80Avant]

ok
so ABS sensors all new, sleeves all new, everything sits at 1mm, discs and pads all new.

Breaks work fine to stop the car if speed is more than 40-50km/h. On very low speeds, ABS kicks in and disables proper breaking!!!

anyone heard of that or am i the first with this problem???

[Dynasty]

Fault codes?

[Christophski]

Try moving the sensors a litte as they may not be seated correctly

[quattro-nick]

maybe You can read all the wheel signals simultaneously with vagcom so you can see if there are big difference between them?
normaly the abs pump kicks in only with to much wheelspeed difference

[mcandmar]

That usually happens when the gap between the sensor and ring is too great, as above move them all closer and retest.

[Error404]

One or more sensor gaps is likely too big, the VR sensor signal amplitude increases with the ring gear speed & proximity, so if the sensor is too far away the signal drops off at low wheel speed. If you can find out which one on VAGcom great, if not try and reduce sensor gaps to more like 0.5mm or better log the sensor outputs on a scope and see which signal goes awry at low wheel speeds.

[newsh]

ABS Woes!!

Or you have a build up of rust/magnetic swarf in the teeth of the rotor, have you cleaned them lately?
Afaik the only way to do this without pressing the hubs out is to remove the sensor and use airline/vacuum cleaner down the sensor hole.

[A80Avant]

Thanks for all of the responses.

There is no dust or anything as all parts are new and so clean.
I take your input of the distance difference as I was told that they are all at 1mm however if slight differences can create a problem we shall be more peristent with their position.

There are no fault codes and I have a small vag viewer which I'm not sure I can read individual blocks but I'll sure try and see if that feature is available.

Many thanks I'll update!

[igor136]

Bomb?

[A80Avant]

There is no hydraulic system on anymore. Just a vaccum servo

[newsh]

Check your speed signal is present at the ABS ECU

[A80Avant]

I was told by the garage that car is running fine now. They took them in and out a few times to adjust them. Did lots of tests and it finally seems to be ok.

I bet it must have been distance difference of the sensors.

Thanks for the inputs!

[igor136]

Wrong distance without error light

[A80Avant]

Yes!! It only happens in my car

[A80Avant]

Turns out the problem is not 100% eliminated. Is there any tool like a gauge to be able to accurately measure the 1mm space when mounting these sensors?
Otherwise I am trying to think of it is worthwhile testing a second hand ABS unit I have...

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