Quote:
Originally Posted by Helmsman
Thanks mate. This document is what I had parts of (believe given by a dealer earlier on). Good stuff.
Btw it also confirms the compensation for aging...
"Tolerance Adaptation
The damper force is diminished as part of the operating time function. Diminishing damper forces are compensated by current (amperage) reductions which are calculated by the tolerance control. This also individually compensates for mechanical damper wear on each axle."
...as well as reset/clearing adaptations:
"Notes on Service
Mechanical wear causes the dampers to weaken over the service life, therefore a running time memory adapts the damper curves towards a harder setting (over time). Faulty dampers must be replaced together (in pairs) on a single axle. After a replacement, the running time memory for the front or rear axle must be reset with the BMW diagnostic equipment"
Interestingly it speaks only about function over time rather than mileage. I would have thought mileage/driving have a greater impact than potentially parking over long time, good to know.
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It is odd that they only mention time but it does agree with what you’ve experienced with your 10+ year old, ~25k mile car which is now much harsher than it was originally. At a minimum, the low-frequency accelerometer response (i.e., chassis/sprung mass motion in the ~1-2 Hz range with a low-pass filter) could be used to estimate the number of damper cycles by counting the number of accelerometer sign changes. This wouldn’t capture cycles from the motion of unsprung mass (i.e., up/down motion of wheels/tires, brakes, hub/knuckle, etc. mass) but it’s better than nothing. The edc control strategy is in the frequency domain so the data already exists.