Hi:

I have a 2007 C230with about 8000 km (4800 miles) on the car and automatic transmission. Since about acouple of months ago, I noticed that when I am stopped at a light and have my foot on the brake, the car lurches forward a bit during the first few seconds of the stop. This usually happens for about 3 or 4 consecutive stops and then the problem disappears. It also seems to happen only when the car has not been driven for a while. I have taken it twice to the local MB dealer and they have not been able to determine the root cause of the problem - theyran the diagnostics on the computer and couldn't really detect anything but decided to upgrade the software for both the engine and the transmission in case it would fix the problem, but so far no luck. Also, teh problem seems to have occurred after Ihad the engine software code upgradeddue to a recall (relatedto use of ethanol fuel).

If anyone has any ideas of the possible reasons for this, I would like to hear from you as I am getting discouraged, especially if the dealer is unable to determine the cause.

 

Sounds like it's time to take it to another dealership since the car is under factory warranty and Mercedes is responsible for fixing it
regardless.

 

I think I can help as mine suffers the same problem. I have an 07 c280 with the same transmission and experience the same problem from time to time. I'm a licenced diesel mechanic so I do have some knowledge about cars and have spoken to a highly trained benz tech (good friend) about the problem. Mine is worse when I'm stopping quickly from higher speed to a stand still and even worse when the engine is cold and on fast ilde. It learches slightly just as I've been stopped after 2-3 seconds.

What your feeling is the transmission shifting into first gear which will ever so slightly blip the throttle. This is a delayed reaction and should not be happening. It is part of a trimmer valve in the transmission which delays shifts ever so slight to allow for smoother engagement or disengagement of the gear. The delay on the trimmer valve can be programed to react faster or slower.

Mine also tends to hold a higher gear longer than necessary while my foot is halfway into the throttle travel before downshifting.

Unfortunately I haven't had time to bring my car to the dealer but my good friend assures me that the transmission needs a 'reflash'.

The transmission in our cars is certainly not the best and after driving a new hyundai sonata, I think mercedes needs to update the programing and/or components to 07 specs.

Hope this helps!

Chris

P.S. your dealer might try and tell you something else but demand that something be done, this is a mercedes and complaining aloud does get you places.