ToanPham

Hi everyone. New member here.

I have a 2011 1st production run MB C250 CGI coupe. Only a few weeks ago, it began to shudder after starting cold. The shudder is felt in the cabin. It happens when the engine drop revs, e.g. 1.2-1k or 1-0.9k. The engine would also hesitate when dropping revs and bounce back up, e.g. 1.1-0.9-1-1.1-0.9 and this causes the shudder. I popped the hood to have a look this morning and could see the engine shaking quite a bit when this happens.
I have taken it back to dealer and they only did a software update and could not get any error codes. Very hard to get a cold start at the dealer even after 8hours of engine off.

Thanks heaps in advance.

ToanPham

Anyone have any ideas?

Doing some research, it could be mass air flow sensor and/or idle control valve. Could it be anything else?

Thanks.