Knightmare69

For those that know what engine braking is, I've been experiencing this in my fiancee's C200 CGi and it's annoying, not to mention quite dangerous at times. What happens is we'll be driving in traffic or stop and go and without touching any of the pedals, the car will "brake". In stop and go traffic this is especially dangerous as I am not touching the brake pedal which means no brake lights are on which means if the car does this then the car behind us is likely to rear end us.

I've tried to recreate the problem but failed as I cannot figure out what causes it. Is it the turbo or the tranny? Even if it's the turbo, my previous turbo cars never had this problem.

Jubair Ahmed

That's weird because I am also experiencing the same type of issue on my C350 which I posted about here: https://mbworld.org/forums/c-class-c...-question.html and was told that it's normal.

To be honest it doesn't quite feel right. Is your "brake" feel a hard break or does it feel more like the kickback you get when you downshift at high speeds? (Mine is the latter)

Thinking I'll have to take it into a dealer to get it checked out if this is a real issue.

Domm

I had that as well. It has something to do with the transmission learning your particular driving style. I reset my transmission computer by turning the key to "ON", then press the gas pedal all the way to the floor for 5 seconds minimum, then turn off the car (without taking the key out or removing your foot from the pedal) and once the car is off, you can take your foot off the gas and wait for 2 minutes. It fixed this temporarily and I reset it probably every 3 days to maintain it. Now I am able to cruise when my foot is off the gas and I accelerate slowly instead of being assisted by engine braking.

Glyn M Ruck

When you say engine braking you are talking about running against compression - Yes?

The car does not apply the brakes!

With a Benz automatic that is exactly what is supposed to happen as the torque converter is locked. These are not old American slush boxes & do not freewheel for maximim fuel efficiency & minimum loss via the TC.

All that doing a transmission reset does for a while is possibly vary the gear that you are running against compression in.

If you want to maintain momentum in a Benz then keep your foot on the throttle otherwise you will experience "engine braking" & it is normal thank god.

Jubair Ahmed

Great solid info guys. Thank you very much.

My buddy was telling me the 2012 models have automatic engine start/stop though having scoured the manual I see no indication of this. I'm not crazy right?

Domm

No, they don't have that feature even though the new 3 and 5 series does.

xijonix

It is actually normal it is just how the adaptive transmissions work. My W203 and cousins W204 is the exact same in stop and go traffic and his is fairly new so nothing to worry about it's just how it is. You can reset the transmission but it'll still end up the same way after a few days. What I do if i know i'm going to be driving through rush hour with stop and go traffic I just drive in dyno mode, It never engine brakes on me I love how it drives in Dyno Mode but it's dangerous if you don't know what your doing, usually everything is disabled BAS, ABS, ESP.

Jubair Ahmed

Ah okay. I'm guessing Dyno mode is the equivalent of Sport mode with ESP off?

Knightmare69

Hmmmm, it has been a while since I reset the TCU but still, I find this quite dangerous and annoying. I guess I'll try a TCU reset again and see how it goes. Thanks for the info.

xijonix

Its a bit more than just the ESP it fully disengages the ESP it's also the BAS Something about dyno mode that feels different It disengages those things ESP ABS and BAS, but it doesn't seem to be running the transmission in an adaptive shifting mode. It always seems to feel the same shifting pattern in Dyno Mode. I am not 100% sure on how it works but the result is pleasant.

Glyn M Ruck

The stop/start feature is market dependent. In SA 2012 Blue Efficiency models have stop/start.

Jubair Ahmed

Ah okay. Looks like that option isn't even available in Canada although mine does have the Blue Efficiency badge.