swohio

Hello all! M156 issue for you. It's actually in my ML63. One out of every 4 or 5 trips now, I'm experiencing a weird - let's call it - surge and retreat when I accelerate. It also wants to shift down pretty much immediately as well in order to accelerate when it does this. The first time, I thought I was just THAT low on gas, but that's not it.Typically, shutting it off and re-starting it seems to take care of it.

What's also strange is that if I use the cruise control to accelerate, it doesn't do it at all.

It does have a eurocharged tune. Thoughts?

Yuille36

It could be something simple like a loose vacuum hose, or clogged injectors. I would try some quality fuel injector cleaner first, this is much cheaper than paying for diagnostics.

hachiroku

flash your tune back to stock and see if that helps.

CaveMan0183

Did you have any luck finding the cause? I’m having the same issues with my 2009 ml63.

swohio

Hey I did get to the bottom of mine actually. After re-flashing the tune, and doing injector cleaner, the intermittent nature of the issue made me think I had fixed each time. But I had not. It kept coming back.

Finally, I was set to put a big stereo in it, so I replaced both batteries. That fixed it once and for all immediately. The aux. battery HAD flashed that it needed replaced periodically. But like most things, I ignored it.

Anyway, it was DEFINITELY the aux battery on mine. Hopefully that's it for yours too!

CaveMan0183

Thank you for responding so quickly. I will give the aux battery a try.

AR_motorwerkz

Try observing it if it happens on a certain rpm range, If it happens on a slope or does it happen if the temp is hot or cold.

Viktori

Have same problem on ML63, but aux battery?? are you serious? looks like big joke.

Have this on cold on slope in most, do you know what is it? esp?