AGFours

Hi All,

I am the new owner of a 2013 E350 Cabrio with only 47k miles, and am experiencing a strange issue - curious if this is normal, or a known issue; when cruising on the highway at 60+ MPH speeds, when I take my foot off of the throttle to coast, it will coast for a couple of seconds, then it feels like the car either starts engine braking or starts braking on it's own and decelerating. It doesn't appear that it downshifts when this happens, but maybe I just haven't noticed. RPMs are in the 2k range, which seem high for a final gear ratio at ~70 MPH, so I tried using the flappy paddle to upshift back into a final 7th gear (assuming that it was downshifting and engine braking) but nothing happens. I can apply a bit of light throttle and it will resume normal expected behavior, but I've never owned a car that would decelerate so rapidly without a foot on the throttle. Also, of note, the 'coffee cup' symbol is persistently on, so I was thinking that the Driver Assist might be trying to brake the car to a stop, thinking that I had fallen asleep, taken my foot off the gas, and was trying to stop the car (much like my newer Audi will do). (???)

I can't seem to find posts related to this exact issue, but I do see a lot of posts related to torque converter lockup issues, (which this potentially feels like) and other transmission TDU s/w issues. Again, maybe this is normal behavior, but doesn't seem right to me.

Anyone have any thoughts?

P

Chevota

Mine does that if the cruise control is on. I often forget and speed up, then when I let off it does exactly as you describe. It'll decel, maybe even downshift (I haven't paid much attention) then when it isn't slowing as fast as it wants, which is usually, it starts hitting the brakes. It gets me all the time because I'm clearly not paying attention if I sped up in cruise, so when the brakes come on I have a second there where I think "wth now", then oh yeah, idiot... Otherwise, no, just normal decel, no down shift or brakes.
The only time it's different is when the torque converter locks. So if eng braking, which I do all the time, at say >30mph, it'll unlock the converter at first and eng braking sux, but after xx seconds the clutch will engage and now it's eng braking nicely. If I touch the brakes or give it very much of gas, it unlocks and I have to wait all over again. If it does that at freeway speeds, which I doubt, I'm not sure you'd notice it much. I suspect it simply stays locked at those speeds. I mean would it unlock at all at 70 unless braking.
The only other time it does anything weird is when getting real close behind another car it'll slam on the brakes. Super annoying but fyi.
It should tell you want gear it's in on the dash. And you can find your car here to see what gears = what rpm at x speed:
https://automobile-catalog.com/car/2...7g-tronic.html
That exact link is for my old '13 E350 but I'm sure it's the same gearing and what not. Or root around and find your car in there. Lots of interesting info in there

AGFours

Thanks so much! That must be it (cruise control on) because we used the cruise control stalk as a turn signal for the first two days of ownership.

BenzV12

That's a beauty of owning a car with a column shifter . I mistakenly turn on the wipers on my other car having driven Mercedes-Benz a long time