BalanBro

So I was messing around in manual mode and found that the car is very jerky when downshifting as you slow down, especially in lower rpms. It only rev matches properly when you are at high rpms or if you let the car do it automatically . Is that how these cars are? Do any of the tunes like Eurocharged V6-V7 correct this behavior? Not sure if this is an ECU or TCU thing, but basically it doesn't seem to blip the throttle at low rpms.

Amr_c63

Normal behavior in lower rpms , I have a v6 tune and also have recently done a transmission service with new fluid and nothing really changed other then smoother shifts . The tcu has a mind of its own some days its crisp on downshifts and somedays its lazy weird but what can we do . Just remember its not a dual clutch transmission or a ZF just a old school sloppy benz tranny.

gtracer

Unfortunately, thats one downside of the 2012+ MCT... It can get very jerky. ECU tune wont affect it. Its not a perfect transmission. Good above 3000rpm. PFL Trans seemed smoother due to torque converter

rene_gts

Yeah, manual and S+ in traffic when just cruising is pretty noticeable, especially from 2nd to 1st. I wish there was a way to stay in 2nd gear in manual also (like it is in C).

BalanBro

That's kinda a bummer. I've been driving manuals almost exclusively for the past 13 years or so. I was hoping to get used to M mode by driving on it every day, but my wife would think the car was broken with the way it clunks downshifts at low RPMs.

NotABaller

I would pay thousands for this feature. Can we get a vendor to get it done?

INS1GNIA

All about timing and letting the car warm up fully first, usually. If you try and downshift below 2k rpm, it does get jerky. 2nd to 1st gear is the only one that is not jerky below 2k rpm, or you can just let the car downshift that one.

I also noticed it depends on speed. 2nd to 1st, the car will shift at exactly 8mph. If you are slowing down and get in between when the car wants to shift and you are accelerating/decelerating, it can be jerky as well.

BalanBro

It seems to work fine when you are driving aggressively, it's when you try to drive slow and keep rpms low that it gets jerky, at least in my case.

AMGC

I have found the only way to enjoy Manual mode in my facelift C63 with the wifie in the car is to shift from 2nd to 1st early as hell each time or she gets car sick from the low rpm clunky shifts. Just kind of feel like a douche sometimes coming up to each light with barks and burbles, but she is used to her Euro Compulsion Abarth so the p31 with cat&res delete is quiet to her. Actually pretty annoying and is quickly driving me to want an ipe set up.

BalanBro

Tried it again today, and in my case it is consistently harsh when downshifting from 4th to 3rd. Basically it shifts fast, but no rev matching is taking place, so it essentially feels like down shifting a manual without rev matching and side-stepping the clutch. Shifting from 3-2 and 2-1 doesn't seem nearly as bad, but I definitely wouldn't call it smooth either.

I did notice that this behavior is only when downshifting while braking. If I downshift to 3rd while on the gas, it shifts fine. I suppose it's best then to just let the car downshift by itself when coming to a stop. This really is a quirky manual shift system. The mechanics of it seem fine, but the programming feels like an afterthought.

gtracer

Mine does that from 6 -> 5. If im not on the gas, it just drops the gear and grabs the clutch, no rev match. Quite odd.

A good compromise is to drive in comfort mode with ESP off but shift yourself. That way, it wont go down to 1st and you can still control the shifts since comfort mode wants to shift around 1600-1700rpm. I usually do that when cruising around the city. Shifts are smooth, I dictate the shift points and it stays in 2nd when coming to a stop. Having the ESP off takes away a bit of the clutch slips so comfort becomes a bit more "sporty"

Savien

Yes mine does the exact same thing when downshifting from 4th to 3rd. It's so jarring and different from all the other shifts that I've entirely stopped using manual mode for regular driving and just keep it in S now where it wont do that. For the record, I have an off the shelf Eurocharged V6 tune on my car and I can't confirm if it behaves the same way on a stock tune.

I really like downshifting myself and hearing the throttle blips when coming to a stop and the shift from 4th to 3rd ruins it for me.

eXstasy

May I ask why you feel the need to manually downshift from 2nd to 1st while coming to a stop?

My experience coming from manual transmissions is that I rarely felt the need to downshift into 1st unless I was already completely stopped or needed the extra gearing/torque for an incline. 2nd gear is enough to get most cars going if you don't need to break the inertia of the vehicle from a standstill. You have enough rolling momentum combined with clutch slip in order to get going again.

In my C63 I manually downshift to 2nd at the most. If I'm coming to a complete stop then transmission will decouple and downshift to 1st fairly smoothly (in S mode or above) for me.

BalanBro

On a low displacement 4 cylinder 1st gear is much more important, otherwise you'd have to slip the clutch for a good while until you built up enough speed or it would bog. But I like being able to downshift on any car, as it has its uses in engine braking. The wet clutch system on the MCT actually makes engine braking really effective on this car, but the jerky downshifts really spoil it.

INS1GNIA

This sound exactly like when you don't let the car fully warm up, it does a harsh/clunk shift from 4th to 3rd. Even if the oil temp is in the white color, it can still shift hard. If you live in warmer climate, for oil temp, 195°F+ should give you a normal shift. If it is a cold morning or day, I would wait till 210°F+. Try/test different temp ranges and see what works best for you. I daily drive 99.5% in manual and came across these issues at first, but now every single shift is smooth like butter on a babies ***.

intence

reset TCU adaptations and see if it helps.

NotABaller

BalanBro

This absolutely could be my issue, as it's still rather cold in the northeast, and my commute is so short that I barely crack into the 180 degree range as I reach my destination. Granted, I don't switch to M mode until the oil temp indicator turns color at 175, but that may still be a bit cold. On top of that, the engine oil temp has nothing to do with the transmission fluid temperature, which I imagine can take even longer to get up to ideal operating temperature.

Jake215

Even in warmer conditions (California) going from 4->3 under braking or coasting in M mode is going to bang if the car has been on for less than 15 minutes, isn't above 220°F (oil temp), or is above 1500 RPM. Again though the oil temp is only a marker. Once the cars warm just always shift from 4->3 above 2K rpm or at 1Kish rpm if you're trying to be quiet. That's simply been my remedy to reduce jerkiness. 6->5 will bang sorta too when cold so just shift at lower RPM's. Ideally 5-7 minutes after the oil temp number goes white it's a safe bet you're not going to receive any of those jerky shifts. If you need the power and don't wanna bang a gear because the car is cold just hold the downshift paddle down and the car will automatically select the most optimal gear for you to blast off into the sunset.