mikefili

I have a C250 that is having drivability problems. It has been in to dealership 3 times in it's 2500 mi life for the problem. The car always seems like it is always in 2 gears too high, takes forever to begin to accelerate, lugs as if you are driving a stick shift car and you are in 5th when you should be in 2nd or 3rd.
Of course it is all about a much too small 4cyl turbo motor in a heavy 4400 lb car. I spent much time with the shop foreman driving new cars and loaners with anywhere from 200 miles to 2300. The one thing that always is constant is the new and very low mile cars are much better than the higher versions. That is all about the adaptive transmission gets worse as the car gets miles. They then reset the adaptive trans and it was 100% better for a few days, now it is getting bad again. Through all this it is obvious that it is terrible with the trans in E and very acceptable in S, shame it cannot be programmed to remain in S.
The engineer said MB position is there is nothing wrong with the car, although he has around 50 drivability cases open for this issue. Some people say we can reset the trans ourself with the hold the gas pedal to the floor thing, service people say the only way to reset the adaptive trans is at the dealership.
Guess I will have to bring the car in every couple hundred miles to have trans reset.

kevink2

"Some people say we can reset the trans ourself with the hold the gas pedal to the floor thing"

Those people be wrong. All that does is tell the ecu where floored is on the gas pedal, and where idle is.

Car has a curb wt of 3400 lbs .... 4400 lbs would be horrible performance.



Some Suggestions:

1) As long as the car is under warrany and the TCU resets by the dealer are free, get them on a regular basis, like @ oil change and once inbetween, for example.

2) The heck with the mpg's, have fun driving the car, and the TCU will likely learn that you are not some old church-person.

3) See if disconeecting the battery and then putting your foot on the brake (electical load) resets the TCU.


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mikefili

Yes, 3400 typo. I am driving the car in S now all the time, much better performance, car now has 600 miles since dealer reset adaptive trans. I did not think that is something we could do on our own. I will continue to bring it back to reset when necessary.

Pete7874

When you're in "E" the car takes off in 2nd gear instead of 1st, unless you put pedal to the metal. That's why it may feel sluggish to take off. It's annoying in our C300, so I can only imagine it's even worse in the C250 that has very little torque until the turbo starts spooling. The "E" is total grandma programming.

I keep ours in "S" as well. It's a bit better. Thankfully in our model year, once you set it to "S", it stays there. You don't have to remember to set it to "S" at every start.

mac911

mikefili

I consider it a big screw up around 2010 when Mercedes started defaulting transmission to E/C instead of wherever the driver sets it.

After all, do you have to adjust your seat, radio, A/C, etc. *EVERY* time you get into the car? Absolutely not.

I encourage you to write MBUSA executive team with this complaint.

I hope everything works out nicely with your car. I'm sure it's still a gorgeous car and fun to drive! Hope it all works out.

DennisV

I contacted MB in Germany and have complained locally.

This car is dangerous because you cannot get out of the way.

Press the gas pedal at slow speeds and it takes almost 2 seconds for the car to react (yes, I know the difference between turbo-lag and downshifting).

kevink2

Good job !

The word is this has been fixed on the 2013 models. Hopefully some TSB's will be issued for you. In the meantime, try a quick press to 1/2 throttle, and other fractions to try not to confuse the TCU and ECU, and drop the 2 sec's of confusion.

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DennisV

1st time this was a problem was when I was making a left turn and misjudged the speed of a car coming at me. I stepped on the gas and nothing happened.

In a normal car I could have gotten out of the way with no problem.

I also belong to:

https://www.mercedesbenzadvisors.com/index.html

and several of us have complained about the throttle lag.

I really hope there is some sort of a recall, else someone is going to get hurt.

Pete7874

Brings back memories of my '00 Accord. It was so annying I ended up selling the car within a year. That was my first and last car with auto trans as well.

kevink2

If you don't mind:

initial speed ?
initial gear, if you recall ?
how sharp a turn ?
how much gas used ? half pedal ?

I know the solution is a proper set-up that is going to GO when you want to GO. Just trying to figure out what went wrong.

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DennisV

Sharp 90 degree left turn from the center lane of a 5 lane highway.

There is a little rise just before the intersection and it's hard to judge speed of cars coming at you.

I started from nearly a dead stop and I was somewhere in the middle when I realized I needed to punch it. So I was going maybe 10 mph.

But it also happens around 20 mph.

It aggravates me when I'm trying to merge and I see a reasonable opening and step on the gas and nothing happens. I pull in front of a car and cannot accelerate to get out of their way.

I've sworn at this car many times since I bought it 10 months ago because it will not move!

tdot_ollie

if you think its bad in the new 250... try the 2011 250 with no turbo. The lag is terrible.

mikefili

Report: as long as I put it in S every time I start it all is well. There is an amazing difference between E and S. car really is acceptable in S... I have found that the car teaches you how to drive it, once that happens it is better. Other night I got in my wife's GLK 350, what a great motor!!!

tdot_ollie

this could all be avoided if they would just run a standard cable throttle.... i've never liked electronic throttles

alsyli

This is what I do when I know I have to merge onto a freeway. You can switch to S even after you've been driving in E (I do it at a stop light). The only problem is that the RPMs at speed are relatively high, and this doesn't make for very relaxed cruising....

kevink2

By punch it did you floor it, like wide open?

Also sounds like S mode, that starts you off in 1st gear vs 2nd in C, helps the situation.

And, apparently you can bring it in to the dealer for a TCU flash. (transmission control unit)

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DennisV

I was going around a sharp corner and it would not be my instinct to floor it. Probably about 3/4 down.

I'm going to call the dealer now and see about getting the update. Thanks.

Pete7874

RPMs at cruising are exactly the same for E and S. At least that's how it is in our 2008.

DennisV

Diffidently not for my 2012 C250 - The RPM's change.

And I think someone said the E mode starts in second gear. But I do not know that for sure.

Pete7874

I said specifically "RPM at cruising", another words, when no longer accelerating. If you're cruising at 65 mph, change the program from E to S or vice versa, and see if your RPMs change.

That is true. E starts in second gear in mine as well. And E upshifts to the next gear sooner than S, but once you reach a cruising speed and are no longer accelerating, the RPMs are exactly the same.

alsyli

And it DOES change; I've looked down at the tach a couple of times to verify. Not sure if it changes if you switch modes when you're already AT cruising, but there's definitely a ~500 RPM change if you've switched over prior. And the engine or transmission is also much more responsive when you accelerate (either at speed or from a standstill). Acceleration is still relatively slow, but at least it's almost completely linear. I think the engine is fundamentally fine; I think the calibrations are a little (or very) off, which sort of describes the C-class as a whole (a highly sophisticated package that has some odd tuning in steering and suspension)....

We used to have a C300. It seemed like the C/S button was more for decoration than for anything else; this definitely isn't the case w/ the C250, which I found kind of shocking and surprising.

On older MBs, I think there to be a little trick where you could force the car to start off in 1st by shifting into "B" while at a standstill and then back to "D."

DennisV, have you verified w/ your local dealer that you can do a TCU flash? I know another poster in another thread commented that the 2013s seemed to be much more responsive in "E" mode and that other posters were *guessing* that an update would be available to owners of the 2012 models....

Pete7874

Interesting. Thanks for clarifying this. Since the gearing is still the same, and I'm assuming the trans wouldn't be running for extended periods of time with torque converter locked up, the only way they could accomplish this is by not allowing the trans to shift into 7th gear when in S mode. Another words, when you're in E, you're cruising in 7th, but when you're in S, you're cruising in 6th.

Glad to hear the S mode is now more distinguishable from the E mode (actually "C mode" in the old C300).

DennisV

Yes, that's what I should have said.

tdot_ollie

a lot of the time i'll try and drive it in tip mode, but usually the shift response makes it way to frustrating

DennisV

Dealer just called back and there is no computer update for my 2012 C250.

BTW, I had a sticker on my speedometer to remind me to put the car in S mode, but it bugged me so much I removed it.