SilverFox

My C55 has about 1400 miles and has developed a problem. When in the "S" mode it sometimes shifts as if it was in the "M" mode. That is, it locks in a gear and does not engage the next higher gear (unless I manually shift it or it goes to redline and shifts itself). This has happened after sitting at a stop sign waiting for traffic to clear or running errands with a lot of stopping, parking and then restarting within 5-15 minutes. Thus, the gear lock is either in 1st, 2nd or 3rd gear. This has happened about a half a dozen times and I know I have a problem either with the software programming or the hardware itself. I have also noted that at highway speeds (70-80 mph) and downshift to 4th and then upshift to 5th it takes the transmission about 5 seconds to move from 4th to 5th but the downshift from 5th to 4th is almost immediate.

Has anyone experienced similar problems and if so what was recommended by the dealer? I intend on visiting my dealer soon but wanted to do a little research prior to the service visit and also experiment some more with the car.

Thanks,

Bob

noka

What was showing in the dash display when it was 'stuck' (i.e. "D" or some "number")? Did you look under your car for leaks? A few people reported slow tranny leaks that caused problems. I would definitely take it to the dealer if any possible "user misunderstanding" is ruled out.

Rgds,
Norm

Karl G

Norm is on to it I think... if you nudge the gear lever or hit the steering wheel shift buttons by accident when you're in D (either C or S mode), then it will limit you to the gear you're currently in (so if you hit it by accident when going slowly or stopped, it will limit you to 1st gear). This would appear to the user as a sort of "M mode" condition. The corresponding gear number will be displayed in the instrument cluster where the "D" normally is. To fix, simply shift all the way back up to D (I think holding down the + button or direction on the lever might work too).

noka

You nicely explained what I was implying. I am certain that keeping the lever pushing momentarily towards (+) will upshift to "D" automatically. Not sure about the buttons but I would guess the same.

Rgds,
Norm

SilverFox

This has happened to me on at least six occasions. I too thought that I had mistakenly hit the buttons so I was very careful when I thought it would occur and it did and I did not hit any of the buttons. So I have ruled out user error but will continue to investigate. I was always in the "S" mode and I do not use the console shift so I would have had to accidently hit the steering wheel buttons. It could have been possible a few of the times but not all of the times.

And what about the extremely slow upshifts at freeway speeds moving from fourth to fifth? I would like a few others to try this and report to this thread on the outcome. I would guess that it takes my car from 3-5 seconds to shift after I hit the (+) on the console.

No leakage on my floor and I do recall that one of the times it stuck it was in "1" and another time in "3". I am hoping that it is user error but am afraid that it is not. If it is not, it is just a matter of time before someone else's car exhibits the same condition.

neoprufrok

I've only experienced it once and I have 1500 miles on the odo. Otherwise - I haven't had any problems yet.

cracker123

not a c55, but a 2005 c230, my transmission fluid leaked recently

hopefully not a big problem.

mwiseltier

I FEEL YOUR PAIN! I had similiar problems with my C55 shifting. I did not touch the shift buttons. In addition, do you feel any degree of "engine breaking" when you take your foot off the pedal while itraveling in gear. Wonder whether it's normal or not. Took it to the dealer and guess what--they said it was normal. Please advise and keep me posted of your result with the dealer. MW WISEL2@aol.com

Zeppelin

Feeling engine braking when you take your foot off the gas is normal for the C32/C55 due too the lock-up torque converter.

cntlaw

I am no expert of mechanics nor tranny , as I only know that MB gearbox learns driver behaviors and adapt itself to 'him'. Guess the memory effect can be at times confused to itself as times goes. Ask your vendor to reset the computer programme and let the tranny learns again.
Of course , I am sure you have thought this point through already.
Just my two cents

cnt'

SilverFox

Will be taking the car in to reset the computer in a few days. In the meantime, I was driving this past weekend and on two occasions at 60 MPH I accelerated at full throttle and let up between 100 -110 MPH and both times the car stayed in the lower gear and would not shift, even when I let up off the throttle. I had to manually hit the (+) to change to the next higher gear. I was in the "S" mode so I don't know what gear it was stuck in but I think it was third. It felt like 3rd because when I let off the throttle the transmission braking effect felt like that gear. I looked at the transmission readout but because I was in the "S" mode the display just showed "D".

I truly hope that reprogramming will cure this problem because this is something that I refuse to live with in a $60,000 car!!!! Obviously, I am very disappointed. This is the first automatic sportscar I have driven in many years and it may be my last. All of the previous cars (M3, Z06, NSX, 911) were 5 or 6 speed manuals.

cntlaw

This happened exactly to me in S mode when my expert friend first drive my C55 :p Guess this happens when someone floor the pedal too hard too quick , the gear won't shift up

So I would call this a 'common problem' to all C55s.
The 3rd gear of the C55 can go up to 160kmh; and I guess the computer 'knows' its limit and stay there until it reaches red line or exceeding 160kmh!

I would not say this is acceptable but seems it is logical that the designer assume we should use M mode if we take every gear to its limit ? crazy:

noka

This does not make sense to me at all. Can you duplicate the "problem" on your C55? If yes, why would you not ask the dealer service about it?

Rgds,
Norm

cntlaw

May be I should....but I never consider that is a fault :p
I never drive the car that hard in S mode and most times I use S mode only I am climbing hills at relatively mild speeds.
( M mode auto downshifts too quickly and jerks when speed below 65km )

cnt

Zeppelin

You will have to live with it. This is the way it was designed. This is the performance part of the transmission software. Why would you gun the car to 110mph and lift off the gas if you were not racing. The car was meant to stay in the lower gears during racing. These are just some of the quirks of an automatic transmission that is programmed for performance.

By the way, you will never get rid of the engine braking effect when lifting off the gas, even at lower speeds. This is also the way it was designed. This is no different than if you were driving a manual transmission car.

SilverFox

If this is designed into the transmission then I think the designer is nuts. I usually drive in the "S" mode and on this occasion I was in the country on a smooth, straight road and decided that I wanted to feel the surge of the powerband. So I "floored" the car at about 60 and it downshifted and I let up at about 100-110 and thought the transmission would then automatically shift into the next higher gear when I lifted my foot off of the pedal, but it did not. I did this again and it did exactly the same thing. Experiencing the powerband of this car is in and of itself gratifying and should have nothing to do with racing!!

This would be no different then when passing a car and depressing the accelerator pedal to downshift the car and then after passing not having the car automatically shift to the drive mode when you slowed down. On a busy two lane road it would not be uncommon to "floor" the car to pass one or two cars. And our cars accelerate quite quickly from 70 - 100. I hope that our cars are not programmed to stay in a gear if they sense you are driving aggressively. If I wanted to shift manually I would move to "M".

I have an appointment next Tuesday.

This would be an easy test for other owners of C55's. I would be interested if this is common to all of our cars or not. Other results are welcomed.

Zeppelin, where are you obtaining your information concerning the performance of the C55 transmission? I am interested in your source. You make me laugh ( not mockingly) with your statement why would you gun the car if you were not racing. Why? What about just for kicks, to pass other cars, to show the acceleration to your passenger or because that is why you paid $60,000 for a performance car. I very seldom road race but find the high performance cars very intoxicating.

I did review my manual and "S" is stands for sport and is for standard driving. Under "Kickdown" it states the following:

Use kickdown when you want maximum acceleration. Press the accelerator past the point of resistance. The transmission shifts into a lower gear. Ease on the accelerator when you have reached the desired speed. The transmission shifts up again.

This is exactly what I did but when I eased off the accelerator the transmission DID NOT shift up again and I hit no buttons!!

Karl G

SilverFox, what you are describing is exactly what "S" mode is designed to do. If you are driving on a track, the only time you'd "floor" the accelerator pedal would be to barrel down a straight stretch of track. It downshifts both because you reached the kickdown point, and because that's what it thinks you want to do (obviously). If, after a bit of grueling acceleration, you lift off the pedal, it can be for one reason only - to prepare for a turn. There is no "cruising" on a track, and hence, the transmission does not expect that you would want to upshift after accelerating hard. It expects that, soon after pulling off the accelerator, you will apply the brakes to get to an appropriate speed for the turn. At that point it would decide whether to downshift again based on yoru speed going into the turn.

"S" mode on this car isn't "feel the surge of the powerband" mode, it's a serious performance mode intended for delivering near maximum performance when driven correctly. What you want to achieve (short bursts of power followed by high gear) is best done in "C" mode, which will also kickdown to give you power but will match it with an upshift when you're done.

NOTE: All of my references to "track" can also refer to "spirited driving".

NOTE2: Here's a source for "S" mode: http://www.mercedes-benz.co.za/PC/Cl...5AMG_trans.asp It reads, "In "S" (standard) mode, the automatic transmission gears down earlier to ensure more dynamic handling. The engine always runs at higher speeds."

noka

The only thing is, with C-mode, the car starts in 2nd and there is no 1st gear unless you manually select it. Maybe there needs to be another mode.

Rgds,
Norm

Karl G

Norm, I know this, but this isn't a problem for SilverFox's 60-110mph runs. If you're in "C" mode and you want a burst of power from a stop, you have the time to slip the car into 1st.

noka

That's true. I'll do a little more experimenting after my break-in period. Still in C-mode for that.

Norm

Zeppelin

I'm not saying gunning the car is racing, but if you run the car up to 110mph here in the states any law inforcement officer would consider you racing. I'm not saying that I don't do the same thing, but flooring the car to 110mph then quickly lifting off the throttle is what Mercedes would consider racing. When this happens I simply bump the gear selector to a higher gear. Good luck trying to fix this issue with DC.

C55NOVA

I drive in S mode all the time and have noticed the exact same thing happening. Basicly after a short burst of full throttle then letting off the throttle the engine does not upshift into higher gear for a full 5 seconds, feels like longer. I thought something was wrong but now that i think about it more I think its part of the design. If you think about driving on a track in a turn you may lift off the throttle to induce some oversteer and you would not want the car to upshift into a higher gear and screw up the exit on the turn, thus the long pause before the upshift. I am going to try the same thing in C mode and see if it happens, if not I can only conclude that its meant to happen that way in S mode.

SilverFox

C55 Nova,

I agree with your accessment. Just how many people actually take a C55 to the track????????????????? If I would have wanted a track car, I think the C55 is near the bottom or maybe at the bottom of my track car list. I do appreciate the opinions and hopefully I will get over the fact that the programmers of the sport mode in the C55 were a bit overzealous in their programming and live with the my "significant other" dictating what gear I should be in.

I think this may be my last automatic transmission. Personally, I think it is over-engineered and I prefer to make my own decisions concerning when to shift and when not to shift. It reminds of a boss that wants to micro-manage!

The greatest thing about these forums is the exchange of info for a better and more accurate accessment of our vehicle. The last thing I want to think is that I have a problem with my car. I will have the dealer check it our next week. After reading these posts I think I need to change my driving habits or trade the car.

Karl G

It's over-engineered, yes. It's also convenient for when you don't want to be bothered by having to shift gears. You could also just drive it in "M" mode. But agreed, it does not match a manual transmission in terms of driver involvement.

noka

I have owned numerous manual transmissions, mostly BMW and a few VW. For a number of reasons, I thought I was ready for an automatic, and I sure hope I am right. No question that in traffic I really enjoy the automatic. On the open road, it's a toss of the coin when I just leave it in highest gear anyway. I don't track my cars, so that was not really part of my decision. I was considering an M3 but I heard some things about SMG I did not like too much and they had the rod bearing recall which I thought I would avoid (even in the '04-'05 cars I was worried). I hope I don't miss the manual too much but only time will tell. If I do, I guess I can wait for the V8 M3.

Rgds,
Norm