CL500 (C215) Intermittent Vibration; ABC system calibration?

[Uky]

Posted this on a U.S. Forum.
No response....

Took my CL500 (C215) for a spin today. When reaching the start of the highway after more than 12km driving at speeds between 50 and 90 km/h (no "shoes") I started feeling vibrations at 100 km/h that got worse and worse

. This on a road that is perfectly flat and recently had new asphalt. Something like a tire beginning to flatten or a loose rim. I realized that I had to stop and made an exit after about 2 km or so after having reduced the speed down to 50 km/h. The vibrations was almost gone so I decided to try to recreate the problem. Up on the highway again. No vibrations (!) Off the highway a few kilometres later and then driving on small roads where I could barely feel the vibrations. After slowing down and breaking at a roundabout I took another highway home. This time I could not recreate the problem.

Drove at 120 km/h for 15 km. Nothing! It was like sitting in the cockpit in a big airliner flying at 30.000 feet in calm air.

I replaced the battery only an hour or so before hitting the road, and I have calibrated the BAS/ESP by rotating the steering wheel fully counter clockwise and fully clockwise, thus putting the "ABS/ESP Failure - Visit Workshop" warning off.

On an empty road I tried to provoke the system by harsh zig-zag driving, up and down speed bumpers but to no avail. No error messages. No squeek or rattle. Rims are tightened and air pressure is to mfr specifications. ABC oil recently changed. Level OK.

I drove 20 miles back home in different speeds. Everything was OK.

Does the ABC system also require calibration for different speeds and on different surfaces in order to adopt and set the servo loop constants necessary for the chassis? If it is a self learning system I can understand why it behaved like this. Is it a bad sensor of some kind? As I wrote above: "No Malfunction" when scrolling the instrument cluster screens...

Any clues?

 

[SG CL500]

Could it be a simple as a wheel balancing weight having fallen off?

Or - I had similar problem in a different car and it was a Lambda sensor.

Both the above (in my experience) only occured at certain speeds, not throughout the range.

 

[Flash]

Main thing is that the problem appears to have disappeared and hopefully will not come back.

My CL was down at MB Stealer on Friday as had a ABS sensor issue and got "stung" BUT am glad issue is sorted.

 

[Uky]

Unfortunately the problem reoccurred today. Weather was excellent so I took "My Precious" to my work and back. Nothing! Then I met with a friend on a parking lot where the problem was discussed. According to him it could not be an ABC issue. We ruled out the rear wheel drive shaft since any unbalance was to be felt constant and at speeds at about 30-40 km/h - permanent. Having experienced nothing I took off for home and of course it reappeared again. This time for about 3-4 km. I tried heavy accellerations followed by violent braking and the problem went away. Not abruptly, but over say 1 km.

I am now thinking of an engine disturbance of some sort (Injector, MAS) The only problem is that there were no <Check Engine> DTC set. I went home and after a short pause I took another little spin. This time nothing (!) for 50 km Whatever it is it is not speed dependant. Instead it occurrs randomly. Since it has been in my garage for most of the winter, I will try to drive it until the tank really needs a fill and then consider some injector cleaning. I checked the fuel consumption after 270 km: 10.6 litre per 100 kilometer mixed urban and extra urban driving, so there seems to be nothing basically wrong with it.

 

[Uky]

Update: Changed the Steering servo oil. Stuff in container was yellowish. Benz' spec says: Same as for the ABC-system (Green colored). Flushed the system and changed to fresh green oil that I purchased at the Benz service center (€27). Since the change I have driven more than 400 km and not encountered the problem one single time. So now I am crossing my fingers..