On my XJ8 1999.
Sometimes my RF wheel start to pulsate when no brakes is in use. The problem must be related to the ABS. I have changed both censors,
both right and left side and cleaned everything. The pulsating is still there, but no codes are set.
Can someone help me?

 

Take it to a good brake shop -- they need to check the run out on the disk. Suspect warped.

 

No any visible clear cracks on the abs ring? Every tooth are crearly seen?

 

Thank you for the answer, but it is not that. It is the brakes grabbing on that wheel alone.

 

The ABS ring is not checked, but I will do that. Thank you.

 

You earlier said that the front RH wheel was "pulsating" and now you say "grabbing". You need to clarify which one it is. Do you mean that the brake on this wheel is "dragging", i.e. not fully releasing after braking?

Otherwise, the only case when the ABS automatically applies some braking force on individual wheels is during the Traction Control but this is only acting on the rear wheels. So, it is unlikely that your problem is caused by a fault in the ABS. If the brake is "dragging", it could be caused by corroded (sticking) piston in the caliper or perhaps by the brake hose that has swollen internally restricting the brake fluid flow.

 

Hi.
No it's not dragging. All brake parts are ok. The piston return as it should. We have tested all that.
The brakes are pulsating, as if the wheel is unbalanced (it is not).
I know that the Traction Control is working on the rear wheels only, but what about the Stability Control? The Stability Control is acting on all wheels individually.

 

The Stability Control does not activate any brakes. It uses only the readings of the ABS sensors to determine if any wheel is about to slip/spin during acceleration based on which it will reduce the throttle opening and, at the same time, momentarily retard the ignition somewhat and cut-off the injection. All these actions are to reduce the torque of the engine until the wheels get good friction again.

You said that you get pulsation when not using the brakes. How did you then determine that the pulsation is coming from the FR wheel brake? Do you feel the pulsation when not really braking but just lightly touching the brake pedal?

 

When you say "we" can we assume you are using professional help? If it is not brakes, bent rim?

 

I can feel it is from the FR wheel, it does not matter if I brake or not. The brake on that wheel will also be hot. The problem is not constant.

 

You have a warped brake disc; have a brake shop conduct a run out test.

 

Thank you for your answer, but the disc is ok. If it was the disc it would have been felt all the time. On my car it can go days between the problem.

 

Have you checked the wheel bearing and all the suspension bushes? Somewhat worn bushes can cause wheel vibration (wobble) even though the wheel is perfectly balanced, the tyre is not out of round etc.

 

The car was on Monday in for its yearly control with no faults at all. The suspension, steering and wheels is controlled. The mechanics could not feel the problem when they drove the car. Two days later it was back.

 

I had a similar intermittent problem on another car and it turned out to be the the inner portion of the brake hose was deteriorated and collapsing. No sign of a problem on the outside of the hose.
Wish that was the 1st part I had changed trying to resolve the issue instead of the last.