M157 Bucking/Idle Issues...Help Needed
 

Hi all,

Just wanted to get your feedback on a few issues I've been having with the car.

Current performance mods are as follows:

Eurocharged Tune Stage 2 (24lbs. boost)
Weistec Plugs
K&N Filters
Straight Pipes
93 octane

I've been getting pretty significant "bucking" that I've seen described here on initial throttle-tip in when the motor is below operating temp. Especially on colder or low humidity days. Has anyone figured out a resolution to this? I've also tried fuel system cleaner and that helped but only for a week or so before it came back.

I've also seen my engine rev ever so slightly on it's own here and there. Just a little jump off idle. It happens very rarely and thus very difficult to capture on video. Always while in drive, usually with my foot on the brake stopped at a light or something.

Also, does anyone have any throttle tip-in lag when the car is up to operating temp? My car is Jeckle and Hyde when the engine is cold versus warm. Super sensitive throttle when cold and laggy when warm. I do TCU resets pretty often because most of my driving is city driving on cold motor which is obviously terrible for responsive, quick shifts.

Last question, does anyone notice that their car seems to choke for air upon WOT? During highway WOT, I feel like the car is struggling to redline almost like their is resistance, perhaps not getting enough air or something along those lines?

I'm sending my ECU back to Eurocharged to have them look at the A/F ratios any other data logged in the next 2 weeks. I'm hoping they can help diagnose these issues.

Appreciate anyone's feedback, advice or questions. :zoom:

Thanks!

Yes!!!! In fact I own the 2015 CLS63 and I have the same issue. Noticed it at 1K miles (when I started to drive it harder). Bucking is the best term to describe it. It occurs on a cold start when the car is in sport/sport+ mode. For instance, immediately upon starting if I turn the knob to sport + at rest, the gear switches from 2nd to 1st gear (naturally). All is good until I press on the gas; it moves forward but is unable to switch to 2nd gear (no matter how hard I press on the gas) and "bucks." It doesn't even make it half way through the RPM allowance before it starts bucking. Its embarrassing to say the least.


The dealer replicated the issue with my car and spoke to MB Germany and they decided I just need to let the engine/transmission warm up. *******s.


The only problem is it also has occurred (several times) after driving for 20+ minutes. In that case, I would drive in C mode for 20 mins or so. Thinking all should be good, I switched to S+ at a red light. Gear drops to 1st. Accelerated at the green and bucked while in the intersection, lol. I had to immediately switch to comfort but when the car is bucking its hard to grab that knob without slowing down to a few mph. In the intersection. In front of everybody. Anyway, it appears to be a permanent issue with my car and a larger issue with the new revamped MCT.


The exact problem appears to be the first gear. If I get the car to buck, and then switch it back to C mode, drive, and then switch it back to Sport +, it wont buck. So it also appears to be an electromechanical problem of gear switching (and not related to temperature per se).


With regard to the cars power, ye some days it drives like a 120K car, other days it feels like a turbo or two aren't working. I haven't pinned the issue, but noticed a huge loss of power one day which coincided with a gasoline smell from the AC. Took it in to test the turbos and they seem to be working fine. I do smell that strange gasoline odor every once in a while, and I know when I smell it the car wont drive well. Its just an extremely finicky car. For reference, I always get my gas from the same station (93 octane).


The car is really only happy in either C or M mode. And I have never experienced bucking in M mode.

Yep Me too....worse in comfort at cold and stops as soon as getting near operating temperature.

2012 E63s 5.5 Bi Turbo (+Perf Pack)

I had an issue where the car would "buck" when cold/cold-ish around 120 - 150 degrees oil temp. At a stop light in Comfort mode with my foot on the brake, the car would start bucking. The dealer re-flashed the transmission software and now it no longer bucks.

Me too, dealer upgraded the firmware on the gearbox which helped, but back again now, I just let it warm up.

Yea about 2-3 months later, the bucking is back, it does go away after the engine is warm though.

Delete

Happened to me as well- I press gas and it'd go into a crazy buckling / shaking without any power despite on the gas. Ended up bringing to the dealer and they found the problem with one of the fuel injectors within one of the cylinder. I'll try to find that reciept which gave me a better detail of what they did to fix it.

Oddly, my car has stopped bucking without any changes to it. Maybe because the weather has been warmer lately?

sorry double post