exi

2021 S63 coupe. CPO. New to me. Under 20k miles.

Have noticed that when accelerating from a stop, there is this jerkiness reminiscent of a manual transmission car. Revs bounce up and down despite me not driving any differently than I ever have. However, haven't noticed this in any other vehicle I've ever driven -- unclear to me if normal due to clutch design and output in this vehicle, or if perhaps there's some ECU mapping or other work to be done under warranty.

Doesn't matter if cold start or warm and driving for awhile. Can be mitigated by really slow acceleration. Seems to happen with transmission in either drive or sport modes. Saw a few threads here that mentioned it, with a couple describing it as normal; others, mentioning improvement with software updates.

Have done the throttle mapping trick (ignition position #2, engine off, floor accelerator, turn off ignition, keep pressed for a minute or so). Doesn't seem to have helped much.

Bigg Willi

Change your plugs,

JohnLane

OP... You have warranty coverage from MB. Take it to them and demonstrate what the car is doing for the service advisor. If needed demonstrate with the tech. This way there will be no 'Cannot duplicate' from the dealership.

superswiss

FWIW, the AMG Speedshift MCT in many ways feels like a manual transmission due to having a startup clutch instead of a torque converter. Best advise I can give you is to drive it like a manual transmission and not like a torque converter automatic. I drive 90+% in manual mode. It needs some TLC with the throttle to drive smoothly. You'll have to modulate the throttle fairly similar to a manual transmission if you want to take off smoothly. I mostly get some jerking if I'm hesitating when taking off. For example in situations where the car ahead of me is not getting out of my way. Helps to delay the take off, so you can be more deliberate with the throttle input or as you already have found out, ease into the throttle instead. This transmission is meant to be responsive, not super comfortable for the most part. It can be driven comfortably with the appropriate throttle input, but for the most part it's tuned for snappy take off and snappy shifts. I love it in my C63, but I always thought it was a bit of a mismatch for the S63 given that the mission of the S Class is supposed to be more luxurious and smooth.

carlosinseattle

Check out this thread from the a member who has a 19 S63 sedan, it might describe what you're feeling: https://mbworld.org/forums/s63-amg-s...ft-points.html

exi

Thanks for posts, all. The additional quoted thread does seem to describe my issue. Had seen that but also others that described issues that were actually "fixable."

Dealer states no codes, no updates, is as intended.

carlosinseattle

There is a fix for the S560's jerky transmission issues. But that unfortunately, is a totally different circumstance. It's explained in this thread: https://mbworld.org/forums/s-class-w...ting-w222.html

I forget all the nomenclature but the main difference is the S560 has a torque converter and our cars don't. When I first got my 18 S63 I was a bit flummoxed by the seemingly erratic behavior, but once I came to relaize it was predictable I calmed down. Last Fall I parked outside my garage on my sloped driveway, backed into my spot. At cold start, I would put the car in gear and try to slowly drive up the hill but the car WOULD NOT MOVE. Once I realized I had to blip/feather the throttle, to engage the drivetrain AND release the parking brake, I was able to calm downand feel better. Then I focused on how the understand how the car was behaving. In my case, it is 100% predictable, and after almost 9 months of ownership I know how to drive it smoothly. I still dislike how the drivetrain's power engages sluggishly when mildly accelerating after coasting/braking. It's even more prominent when doing a quick stop at stop signs and traffic circles. That's the only thing that really "bothers" me. All the rest are no big deal. If I could tell someone one thing before buying one of these cars is you can forget about forgetting about transmission behavior. In other words, you'll always need to pay attention and think of it as a manual transmission car, just without the third pedal.

I'm a little disappointed to realize that MB designed the drivetrain to obtain ridiculous 0-60 times (bragging rights) at the expense of a more refined luxury car experience. To me a luxury car allows you to forget about the experience of driving, and get from point A to point B as effortlessly as possible. I honestly thought I was getting both the luxury and performance with my S63, and 95% of the time it feels that way. But when it doesn't...it doesn't. I know you'll do fine with getting adjusted to it.

haa

That is partially why the S65 has the 7 speed AMG Speedshift transmission as opposed to the 9 speed MCT. Smooth as butter but slightly slower 0-60 than the S63.

superswiss

Yes the S65 uses the 7G Tronic, slightly tuned by AMG. That's the regular torque converter automatic. Supposedly the MCT couldn't handle the torque of the V12, neither could 4Matic.

The 7G also starts in 2nd gear when in Comfort mode for additional smoothness off the line like most other regular automatics these days. The 9-MCT always starts in first gear and the first 7 gears have shorter ratios than the 7-speed, which all makes it more jumpy and more high strung. The S65 is probably the better package as an S Class AMG.

carlosinseattle

Just curious; where did this information come from? Was that a MB release or writer speculation? I also wonder if it was marketing talk or were there any test done, either by MB or some aftermarket company? The weak point wouldn't be the axles, but the "transfer case" portion of the drivetrain. I think it all came down to packaging; impossible to fint the V12 with the MCT 9 speed. A space issue, not a strength issue.


Better is subjective. Maybe so, but for $50K more, and AWD. Even at the same price AWD is better for me, and most people who live in areas where climate is an issue. I NEVER drove my S600 in the snow, and most of the time left it in the garage when it rained. I didn't even think about an S-class again until a buddy fo mine in the car biz told me new S-class cars come with AWD. As far as jerky acceleration, my car literally never jerks. And I think the OP will be driving smootly as well once they figure it out.

superswiss

I don't remember where I read it. It comes down to the clutches being able to hold the torque. The clutches have to be made bigger to hold more torque. The 9-speed is actually the same size as the 7-speed. MB managed to add two more gears with some clever tricks w/o making the transmission bigger. It's also lighter than the 7-speed. However, the transfer case adds length to the transmission, so in RWD setup the transmission is shorter, so that could be the driver behind RWD vs AWD.

Yes, RWD is not the best in the snow. Fortunately, I don't have to deal with that. In the Mediterranean climate here I'm on summer performance tires all year. Not a big fan of AWD. Just makes the cars understeer, because the front wheels have to share the available grip between steering and propulsion, and steering response/feedback suffers. Also, above about 30 mph AWD just causes higher drivetrain losses, adds weight and doesn't provide any value. Driving in snow comes down to being able to stop and AWD doesn't help there. That's all down to the tires. If you can't stop, there's no point in having enough traction to start. So it's a big compromise for a few days of snow. Had my share of performance AWD cars and they just don't deliver the kind of steering and playfulness I desire. 4Matic+ is not bad as it can actually send 100% of the torque to the rear and even fully decouple the front axle in drift mode in certain models, but you have to turn ESP completely off before you can enjoy pure RWD.

carlosinseattle

Agreed...EXCEPT for one point. AWD's advantage is about getting going, not stopping. AWD does NOT help a car stop any faster, never has and never will. And even more important than snow, rain. Rain is the biggest issue for me. We deal with many months of wet roads in the PNW, made slick from oils on the road. Accelerating, especially while also turning is made so much easier with AWD versus RWD. In those situations you have for more understeer with RWD than AWD. I'll post videos to explain the difference if you want.

superswiss

That's what I said already. AWD doesn't help you stop. You may have misread. That was one of my points. With AWD you might have traction to get going, but if you can't stop then better leave the car parked in the first place. As for your RWD comment, my guess is your RWD experience is with open differentials. Frankly, RWD sucks if you have an open differential. A proper RWD needs an LSD. If you understeer in the wet with RWD and LSD you are doing something wrong. You'll be oversteering and drifting like me in the snow below at least with ESP off. The AMG S Class never had a locking rear differential. I believe the W223 C63 SE finally does, but most other 63S models like my C63S had an electronic rear locking differential for the last decade or so. RWD is a completely different ballgame with a locking differential and in addition I have the 9-stage traction control system from the AMG GT R, which lets me regulate traction control to get the exact desired wheel slip. Driving in the rain can be as safe or as hooligan as I want.

carlosinseattle

You're right, I read that backwards, sorry about that! You're one of the most knowledgable guys on the forum so I should have noticed the error. However, AWD is so much better than RWD for me and how I drive. I have a fairly sloped driveway so just climbing it to leave is so much better with AWD.

superswiss

Absolutely understandable. RWD is definitely not for everybody. Oversteer is much harder to control than understeer and with open differentials you get stuck pretty easily as the car is trying to slow down spinning wheels with the brakes to the point where nothing is moving anymore, or if you turn off traction control you have one wheel spinning and the other one is not receiving enough torque to get you up the driveway. That's where the locking differentials come in and lock the rear wheels together at variable ratios, so torque is sent to the wheel that has more traction and get the car going with a good set of tires for the given conditions. Similarly when cornering, torque gets sent to the outside wheel to push the car around the corner instead of risking wheel spin on the inner wheel and the car losing momentum. This is called torque vectoring.

TripleDown

Sage advice here. I have given up on the AMG SpeedShift as an auto trans and I too think of it like a manual. Even in S mode it's always trying to drive around at 1200 rpm so I just put it in M and pick my own upshift points. The herky jerky take off from a stop is still there though. The folks removing their oil pump solenoid report better low speed behavior and some claim it totally solves this issue. I have not done that mod yet but may this summer. I'll gladly give up .5mpg to know that my oil pump is always at full pressure.

carlosinseattle

What's fascinating is how the car behaves with cruise control engaged; refined and poised. I use cruise during traffic slowdowns on the highway and the car smoothly transitions from braking to accelerating with no lag in drivetrain engagement. It does that whether I come to a full stop or slowing from 45mph to 20mph then accelerating again. That tells me that mechanically the car has the ability to drive smoothly.

OP, you should try it with distronic cruise engaged and see how it behaves when the car is in full control.

superswiss

Yes, DISTRONIC operates the MCT very smoothly, so I agree, mechanically there's nothing wrong with it. I think it's simply that when driving yourself they made it engaging, whereas if you are just chilling with DISTRONIC, they made it smooth to sit back and relax. That's how I use DISTRONIC. If I just wanna sit back and be a passenger, then I use DISTRONIC, otherwise I wanna be engaged.

superswiss

Just adding one more thought to my post. I think fundamentally, those who buy AMGs seek an engaging driving experience whenever they drive the car, but still have a level of rest comfort that it can be driven daily w/o getting beat up. At least that's my perspective. The beauty of AMGs is that you don't have to drive them ***** out for the driving to be an experience. Every drive is an experience and yes that means there is increased NVH that makes you feel the machine under your butt. It's all intentional. There are plenty of smooth, isolating transportation conveyances out there if you wanna be pampered. I currently have an EQS 580 loaner. Second one within about a month as I was unlucky and got my windshield cracked shortly after the last service, so my AMG just got its windshield replaced. Looking forward to picking it up tomorrow. The EQS is a nice, smooth car to just drive from A to B, but I'm already bored driving it. It's fast and has great throttle response compared to the typical ICE loaners I used to get, but it already feels boring and I haven't even driven it much. There's zero engagement.