a.keen97

I know there are a few threads that reference this issue but I haven't seen any specifics on where to proceed. I recently purchased my car, 07 clk 350, for a great deal, but with a limited service history. It has rough shifts from time to time when slowing to a near stop, etc. They are not terrible, just enough to notice a lag. I have never gone into limp mode nor experienced any other issues. 99% of the time the car shifts flawlessly. I wanted to know if you thought this was something I should have checked out or if it is just the nature of the vehicle/tran (from hat I have read, I assume the latter). I had read that maybe a tran update may fix this, but others said even after replacements and re-hauls, there is going to be a rough shift 3-2, 2-1. If an upgrade is a possibility, does anyone know the most recent available update and somehting I could reference by as the dealership seems to write off the thought of an update immediately. I'm very thankful for your knowledge and appreciate your time.

BenzAMG99

Are you warming up the car before driving?

a.keen97

Not necessarily, but even after being driven for a half hour or more, this rough shifts tends to happen periodically.

Reanimation

If you have the money book it in for a gearbox service since you say the service history is limited, I bet the down changes improve. What mileage?

Rudeney

Your transmission needs a fluid and filer change (including torque converter drain) ever 40K miles. If this is a "clunk" when it downshifts from 2-1 as you are coming to a stop, then this can be solved with a firmware update to the TCU. Basically, they delay the 2-1 shift until you are fully stopped. It will cost about an hour of labor time at the dealer to do this. If you also need a fluid/filter change, you may get get them to do it as part of that service - usually around $450.

a.keen97

Thanks all! Rudeney, do you have any specifics that I could reference the TCU update by? Dealer just says "it's been a while since an update for this Rena's has come out and I'm sure your car, being 10 years old has already received the latest one." They want to charge $200 just to search for an update, which I think is ridiculous. I'm going to go forward with a train service, hoping maybe if I had specifics on firmware I could lump that in, without them having to "search".

thanks a lot all

xsever

If someone here on the forum has a W209 with the 7-speed transmission and access to SDS, they can use the latter to read the firmware version of the TCU and post it here.

I have an SDS, but my car has the 5-speed not the 7-speed.

Good luck!

Rudeney

I'm can't find the TSB, but there was definitely a software update that solved the clunk when slowing to a stop. I'd find a different dealer, or at least someone else at that dealer to talk to about it.