Nullabgleich nötig nach Wechsel des ESP Quersbesch.-Sensors? | Posts 16+

Quote:

This vehicle does not have ABS rotors; instead, it uses active wheel speed sensors that capture the signal via the wheel bearing (magnetic ring).

However, it doesn't change the fact that the sensors can sometimes provide inaccurate wheel speed readings or strange values.
I assume you've already checked that all the wheels are displaying the same wheel speed values?

This problem with brake interference hasn't just started recently; I think it's been going on for about two years now.

The problem was addressed systematically: (step-by-step).

- Brake hose (front left)
- Brake caliper (front left)
- Wheel speed sensor (front left + rear right)
- Wheel bearings (front left + rear right)
- ABS unit (control unit with the same part number + hydraulic block with the same part number).

- Next, we'll be looking at ESP sensors, and a zero-calibration might already be helpful.
or at least brings about a change, whether for better or worse.


Wheel speed values were also read, and they provide the same values, except when...
"The rotation rate changes. And rotation rates of 8°/s or more are observed with a steering angle of..."
"Values of 0.60° are already quite unusual, and furthermore, the significant difference between..."
both sensors (e.g., 14°/s vs. 0.7°/s) or even different signs.
(99% ++ or -- and 1% +- or -+) I will provide a Screenshot to illustrate this.


But it's all within the acceptable range, so it's not really a mistake.

Okay... Is the steering wheel pointing straight ahead at a steering angle of 0 degrees, and not tilted to one side?

Regarding the strange sensor readings, are they really securely fastened? I seem to vaguely remember that we once had a case in this forum where a sensor was loose.

Best regards, Rainer.
Edit: https://community.dieselschrauber.org/en/viewtopic.php?t=25412

According to the RLF (German Road Traffic Regulations) from 2014 onwards:
After replacing the ESP sensor module (G419) using VAS 5051b / 5052, perform the following procedure in the brake electronics control unit:
- Calibrate the G200 transverse acceleration generator.
- Calibrate the G251 longitudinal acceleration generator.

It can be selected directly in the VAS system after connecting to the control unit, not through the basic settings.
What features does the VCDS menu offer? (I'll check it out on my own car tomorrow).
hg
Herbert.

Quote:

What does the VCDS menu offer?

It depends on the ESP model; usually, you first enter the login code into the ESP and then select the appropriate default channel.

Best regards, Rainer.

I'm seeing the same issue. The RLF and VCDS options don't seem to be compatible in this case.
hg
Herbert.

Here are some excerpts from a logbook entry.

One can clearly see the differences between the two.
Sensors detect and the similar steering angle.
Speeds can cause completely different rotation rates.

The transport was carried out on a dry road, therefore...
No interference from fluctuating grip levels or similar factors.

Sensoren sind ordentlich angeschraubt und fest. I was also thinking that.
be aware that they might be loose.

The steering wheel is perfectly straight when the steering angle is 0°.


@Rainer; The pictures have been retaken because the box containing the data would disappear as soon as any key was pressed on the keyboard.

Hi,

Is the steering wheel really pointing straight in the image "Logfahrt_Drehrate2.jpg"? The wheel speeds are far too different, which is no surprise considering the ABS/ESP is intervening. Are different wheels mounted on the left and right sides, possibly from different vehicles?

Best regards, Rainer.

Hello Rainer,

I'm not entirely sure what you mean by "wheels."
The vehicle was equipped with four identical winter tires.
carried out, tread depth is almost the same on all tires.
identical (difference within a 0.5 mm range).

Summer tires present the same problem.
(Original Audi rims + AO tires)



But from these data, it is clear that when...
As the rate of rotation approaches zero, the speed also becomes identical.
(The maximum deviation in image 4 is 0.9 km/h, and it also involves driving in a curve.)
So, no intervention from ESP either.

The question is, why do the sensors think that most of the time?
The car would be in a "spinning state."


I'll be checking the sensors (there are two different types) sometime in the next few days.
exchange and check if both or only one of them are suitable for this.
responsible for strange behavior.



With a steering angle of 1°, as shown in Figure 2, the steering wheel is positioned...
analog to the steering angle, it is skewed.


Has there been any progress on the ESP zero-offset calibration?
Does it comply? (from the manufacturer's perspective)

Hi,

Quote:

I'm not quite sure what you mean by the wheels. The vehicle was equipped with four identical winter tires. carried out, tread depth is almost the same on all tires. identical. (Difference within the 0.5 mm range)

"Then you should check the pressure in the right tires. A difference of 2 km/h between the left and right sides is too much (Logfahrt_Drehrate2.jpg, straight driving), especially if the tires are the same size, right?"
And forget that nonsense about calibrating your sensor; you have a completely different problem when the wheels on the same axle have a 10% speed difference!

Ross-Tech won't be sitting in front of the computer on Christmas Eve because of you, and neither will I.
Don't you understand that a 10% speed difference between the right and left wheels is a significant amount when the car is supposed to drive straight (a 1° steering angle = nothing = straight)?

What is the size of each wheel, and what are the tire pressures?
Just write it down here.

Best regards, Rainer.

sportdiff wrote:

... The question is, why do the sensors think that most of the time? The car would be in a "spinning state." ...

Because you probably can't see the forest for the trees...

Okay, let me summarize:
Despite swapping the ESP/ABS module and control unit, the error persists.
If the "new" block doesn't have the same error, then the problem must lie in the periphery. Your search is currently limited to the sensors, but there's another aspect to consider.
For proper operation, the control unit (STG) requires a perfectly clean power supply. This includes not only the power supply itself, but also its grounding.
Here's where I would start looking in your case.

Reason:
When I look at the image "Logfahrt_Drehrate.jpg" and follow the graph from left to right, I get the suspicion that there might be issues with the mass.
To the left, the graph starts to fluctuate wildly. In the middle, everything looks usable, but then it fluctuates wildly again to the right. This affects the steering angle and also various other sensor data (wheel speeds, etc.). The steering angle sensor seems to be particularly unstable. In any case, I don't think you can turn the steering wheel that quickly. At the same time, the wheel speed sensors start to provide nonsensical values.


That's where I'd start looking. The sensors and control unit are probably okay.

@Bertil: I think his log will be a mess, I see something in the image with over 1400 seconds, which means a lot of steering wheel movement. The zoom function in KDataScope wasn't understood either; the image is useless except for the instantaneous value.

It would probably be too simple to land here, just 100 meters straight ahead.