mmgwd

Hi everyone I hope you have a great weekend ahead of you. I've had a problem with my 2018 c43 w205 that I'm hoping this group can help me find out if this is a flaw in design or if my car has an issue. Basically the issue is it buckles back and forth when I apply the gas just after it has down shifted to first gear while in sport+ mode. If you want to help, the steps are below of exactly how to re-create this, please test and let me know your results.

Here's how to re-create:

1. Set to Sport+ mode, automatic (not manual/paddle mode)
2. Set main display so you can see when the vehicle changes gears
3. Drive the car up to 2nd or 3rd gear, then let it slow down so it shifts from 2nd to first
4. The instant you see the car shift from second to first gear apply the gas as if you were accelerating after making a turn

Does your car start buckling back and forth while applying the gas just after it down-shifted to first?

My car is under warranty, I took it to the dealer and they said the transmission comes back with no error codes, so "nothing to fix." Ran a search and the closest I could find was this https://mbworld.org/forums/c-class-w...ift-issue.html but it's actually a different issue.

Anyone testing this and reporting back would help me to figure out if I need to open a case with MB or if every C43 is like this.

THANK YOU!!

W205C43PFL

That is commonly known as the "bunny hop" behaviour. It is normal at least for the C43. The first gear's gear ratio is short so the throttle is extremely sensitive in first gear. Installing software updates to the TCU mitigates this because MB received complains so they tuned the software. It doesn't bother me anymore as when it happens I just upshift manually or instead of hesitating with my throttle input, I straight up floor it. Mines is a 2017 by the way and I believe I experienced this since I got it new.

C43 Fun Haver

Yup i completely agree, i got my 2017 C43 about 6 months ago, if you're light on the throttle in first gear, sport+ mode, i call it a first gear lurch, like you said. dont hesitate with the throttle in first, same thing coming to a stop with shifting, people say it has a hard downshift, you just have to find the right rpms while downshifting

mmgwd

Thanks for replies. It's hard to tell if what I'm experiencing what others are describing, mine sounds a little different but maybe one of you can tell me: Mine doesn't do it at any time unless I press the gas right after it downshifts to first. It doesn't matter if I push the gas hard or if I ease into it, the entire car will jolt back and forth and it will never stop jolting unless I let off of the gas. If it starts jolting and I press the gas harder it will just continue to jolt the entire car back and forth.

What do you think, same thing?

elealschuman

I have a 2016 c450 and like others have been describing, mine does the same thing. I am by no means an expert, but you're describing is the same as everybody else, and is just something that the car does. I'll usually just shift if I notice it happening or let off, but it's not an actual problem with the transmission that I'd be worried about.

E55Greasemonkey

Normal. Your car is equipped with a wet clutch instead of a torque converter.

mmgwd

Really helpful responses everyone, good to know there's nothing to resolve. Enjoy your weekend

superswiss

There are numerous threads on this. As said above, it's normal. Anybody who has ever driven a manual transmission car has experienced this. It's more common with aggressive transmissions. It's actually your foot that causes the rocking back and forward. As the car moves, your foot doesn't remain steady and follows the rocking motion of the car in opposite direction, whipping it up. You have to keep your foot steady, push down on the throttle pedal or let go of it to settle things down.

No it isn't. The C63 is. The C43 has a torque converter, but with an aggressively tuned lockup clutch.

C43HeartBoost

I had this problem a few years ago when I first bought my c43. It happens very infrequently now - which I attribute to learning how the car wants/likes to be driven. In lower gears while in Sport+, the car does not like 1/4 or 1/3 throttle acceleration. Your mileage may vary.

jhpmbusa

Welcome to the rodeo!!

ucorvet

OK. So this guy ( ) claims the bunny hop behavior on his C43 was fixed with recall 2018040007 (see attachment). I think he is saying that as part of the safety recall (seatback lock) that there was an ECM update included that fixed the problem. True or untrue?

mmgwd

I can't say for sure what, if anything, was wrong with the persons Mercedes in the video, but the issue I was describing isn't actually a problem at all. I have since then drove multiple other AMG's and they all do the same thing. It's happening because the vehicle is bouncing your foot back and forth on the pedal, so you need to either let off the gas, or push down firm. It's definitely not a problem. I hope that helps.

GermanCarShow

@ucorvet Someone earlier in this this thread said there is a software update that improves this behavior.