clk209nic

Guys i have been searching months, visited 2 different dealerships and still my problems not been solved.
Here is my issue,

Comfort/Sport/Sport + i have what is felt like slipping 1,2,3,4,5 when driving at normal pace. when driving hard the car up shifts and down shifts great.

The car feels like it jumps rev 300-500 each gear before it changes. Changes to 5th gear will a speed of 50km/h and car feels crap do drive.

Transmission oil changed less than 15k. One dealer re adapated the gearing but that didnt solve anything. They found it pointless to update the transmission tcu.he said it will require a torque convertor replaced, transmission service again and then see if the problem goes away.

Other dealer said i that is how these MCT transmission behave which i am not convinced. 600euros spend and car has not changed. Xentry found no fault codes anywhere, no transmission errors.

Can someone shed some light my way or even had similar symptoms and if they have been repaired.

roadkillrob

Well the dealer that said you would need a new torque converter if they update the tcu I would avoid as that makes no sense and you don’t have a torque converter at all in a 2012.

clk209nic

I know in the MCT transmission we have wet clutches. Can they be worn but wouldnt that give me the slipping at al speeds.

Slow_c63

iTrader: (1)

You’re not slipping, that’s for sure. 5th gear at 50kmh/32mph is.... ummm... someone get BLK in here lol.

In all seriousness. Have you tried resetting the TCU?That would be my suggestion for now. Disconnect the battery overnight. Enough time for a clean slate. Reconnect the battery and go for a drive around town. This will readapt the ECU/TCU to your driving.

C63AMGeez

Who serviced the transmission? I’d play it safe and service it again at the correct temp and with correct fluid before jumping to conclusions.

BLKROKT

Sounds like you’re stuck in “C”. That’s what it feels like.

BalanBro

Are you tuned or are you running the stock ECU map? Some of the flash tunes are known to create shifting issues similar to what you are describing.

hachiroku

all shelf tunes outside of renntech cause transmission degradation due to the way the tunes are built. transmission degradation results from hunting of gears due to mismatch of engine output and transmission expected torque. the transmission won't lock out a gear if it becomes confused in its internal calculations on speed versus torque versus requested driver input.

if you're on a factory tune, it would be quite odd for your transmission to hunt for gears or slip. these transmissions especially the MCT with factory power production should last the life of the vehicle with regular upkeep. the older torque converter transmissions at times could have issues with seals which results in odd shift performance when the transmission is cold.

clk209nic

I have a tune on the car. It has been on there since the day i purchased the car. I can feel the 'slipping' more when the transmission gets warm. i wont notice any when cold and just crusing along until the car is up to temp.

The transmission was serviced by Mercedes.

clk209nic

Exactly this Barry. the car feels confused when trying to adapt the correct gear at the correct speed. As mentioned previously, only does it when transmission gets to temp, has no issue when driving hard up or down shifts on when crusing alone the gears seems to be all over the place

hachiroku

let me know if you need a proper engine tune that will improve shifting speed and performance beyond OEM.

INS1GNIA

You could always try to capture a video of it happening if possible. Not saying it will help but might be able to give better insights.

Diabolis

Unless you have extensively tracked the car, I think Barry's diagnosis is the correct one. I'd start with a TCU reset - see https://mbworld.org/how-tos/a/merced...and-tcu-388898 and https://mbworld.org/forums/c63-amg-w...tcu-reset.html - and go from there.

BalanBro

A quick diagnosis would be to flash it back to stock, and reset the TCU to allow it to readapt. If your slipping issue goes away, you've found the culprit.

Boostaholic84

This TCU reset is complete nonsense.

hachiroku

LOOLLLLLLLLLLLLL

you know...for years I didn't want to share. those "tuners" that tell you to reset TCU's or disconnect batteries are just giving you the Placebo effect. sadly you all believe it because you want to believe the 800 dollar tune is everything under the sun.

here are the facts...
i've said this many times and i'll repeat it again, the bosch motronic 9.7 engine computer is more advanced than MANY standalone consumer level fully programmable computers. aem, haltech, ems, blah blah. the bosch motronic 9.7 blows them out of the water for the amount of processing power that is required to utilize actual thousands of maps. now, if you have a computer for the engine this advanced, why wouldn't you pair up a similarly advanced transmission computer? well, here are the facts...the TCU will ACTIVELY manage shifting times, harshness, shift points, etc live and directly. there is no such thing as a "transmission relearning, TCU reset, or TCU adaptation, because the TCU does this actively every single time you accelerate from a stop. when all things are running in their optimal conditions, meaning your engine tune is pinky's up perfect, this will happen live as you drive every second. if you've just reset your fuel trims, the TCU will also reset some of its shift adaptations and can shift harshly until the transmission is fully up to operating temperature. once this occurs, it will take 3-5 minutes of regular driving for the transmission to fully adapt and from then on it will ACTIVELY adapt shift pressures, shift rpm, and shift speed LIVE and every second.

TCU tunes for the M156 version of the 722.9 are snake oil and only exist to bandaid fix bad tunes. do you want to know how you know you have a bad tune? your fuel trims are all over the place for LTFT and STFT. BOTH should be as close to zero as possible. you know the owner of said company loves to get into verbal fights and arguments on facebook and they seem to be nonexistent over the past 5 years on the W204 C63 forums as well and you wonder why.

Diabolis

How is a TCU reset useless as a first diagnostic step? I am certainly not saying that it would solve the OP's problem, but it would eliminate the possibility of the transmission shifting poorly in case it is because the car was "driven like a grandma" for the last 50 km, or alternatively it would confirm that that is not the issue and that further investigation is necessary. Again, what am I missing?

hachiroku

@Diabolis , sorry my previous post wasn't meant to be a directed comment more so a general comment to clear up the false and misinformation being provided by "tuners". in the situation of a factory tune, yes you are absolutely correct. he did reach out to me through DM that he does have a tune. in these situations i've instructed many to flash their factory tune and report back of resolution. 100% of the time the issue is resolved by flashing the tune back to a factory tune.

C63riley

Were you able to resolve the problem having the same issue now but my car is stock