Hi All,

I encountered a strange problem while driving today. While driving on the highway at about 100-110kph, suddenly the car started shuddering - it was like I was driving quickly over rumble strips. It was like this for about 5 minutes, despite braking and slowing (there was nowhere for me to stop), and the next thing it was gone and everything was back to normal.

This happened once before about a month ago, and other than these 2 times, everything has been fine.

I should add that the brake discs, bearings and hubs are all new, as well as the tyres, engine mounts and transmission mounts. The suspension and steering were inspected about a month ago, so it doesn't look like it's any of those.

Anyone any ideas what could have caused this?

Thanks in advance

do you feel it in the front or whole car? did you check driveshaft flex disc?

Check DTC codes for missfire. If found any, replace new set of spark plug leads and related ht-coils.

Thanks for both your replies.

Quant, it seemed to be coming from the front of the car, but was difficult to tell. The flexidiscs were replaced about 3,000km ago, so these should be OK.

MouTine, interesting that you mentioned misfires. The last time my car was in the garage, the mechanic told me I had an intermittent misfire on one cylinder, but that it wasn't urgent to resolve it. When the car idles in neutral, the engine does vibrate, (but only very slightly), so this would indicate a misfire. But idling in D with the brakes on, there's no vibration.

Would misfires have caused the shuddering? Especially very bad shuddering as if driving quickly over rumble strips?

Thanks

If the ECU detects certain amount of missfires in a certein time cycle it will shut down cylinder or cylinders. Engine will chake and loose a lot of power. You will deffinetly notice that. And when you switch of the engine and start again all is reset until whole thing happens again. Seen that happen in my former CLK55 and two of my friends CLK's. All M113 powered.

Thanks MouTine.
One quick question though - does it only reset after switching the engine off, or could it reset itself while still running?
The shuddering I experienced stopped while I was still driving, after about 5 minutes.

No idea but I believe not. Did you get amber Check Engine Light?

No, the CEL didn't come on.
When you had the same problem with your 55, did you experience the shuddering while driving?

Thanks

Allmost two years ago when I bought my first CLK55. I was driveing home 700km trip and it did it if I remember right three times during that trip. And after that few times until I throwed new plugs, leads and three coils. There is a topic about that somewhere.

Thanks again MouTine. Much appreciated
Sounds like the same problem. I'll have to check/replace the coils - probably due a new set anyway after 130,000kms!

No problem. I allways want to help others. Anyways... Just wanted to say that don't jump directly into my idea. Do your research and diagnostics. Your problem might be whole diffirent than mine. I wish you a luck. Please remember to update this topic if you find a problem and solution.

I had a similar problem to this out of the blue yesterday afternoon.

I have a 2005 S55.

I'd had my TCU reset in the shop to make it shift better.

Driving home I was going about 140 KPH in cruise control and suddenly developed this shudder out of the blue. Never experienced anything like it before.

I slowed down to about 110 KPH, and after a few minutes it went away.

Car was fine for rest of trip.

Until I was almost home and driving about 50 KPH when the shudder reappeared. And again, went away while driving.

This can't be wheel balance related or anything like that in my opinion.

Does this sound like the same issue as above?

Car runs like a dream otherwise.