AMGaintBAD

Hi guys, I haven't seen anybody else post this. I have a 2013 c63 coupe. I drive 90% in S+ mode. At first I thought my car had transmission problems but now I'm not sure.

When driving and I'm in 5th or 6th gear, going about 100km, if I let go of gas and TAP the gas right after, it will downshift to 3rd gear at 4000rpm. If I don't let go of the gas, and press the pedal a bit more, it will eventually downshift to 4th.

This is very annoying to me, because sometimes I'm cruising along in 5th or 6th, just feathering the pedal, and suddenly, it will downshift to 3rd, revving the engine up, and probably startling the car next to me. This is especially problematic when I'm going through a long turn on the highway. It catches me by surprise. I don't mind if it just downshifted to 4th, but 3rd is too much of a jump.

I was going to take the car in for mercedes to look at, since I wasn't sure if this was built in, but now I'm thinking it could be designed that way.

You guys have similar experiences? S+ mode only.

jrcart

Lol, it's called macthced rev downshifting, it's supposed to do that. In very basic terms it revs the motor to catch up with the rpm of the rear tires in preparation for a downshift. The reason it goes from 5th or 6th to 3rd when you blip the throttle is becuase a blip signals the motor that you want to be aggresive and the ecu and tcu work to get you in the optimum gear for the speed you are traveling.

mr747

maybe you should leave it in c mode them

CarHopper

This is why if I'm driving spirited I generally just go into S. Much less... aggressive/weird. S+ is fun when NOBODY is around and you are absolutely just hooning around and don't want to shift yourself. That said, I usually am either in C or M.

jcfay

I'm always in S+ cause I'm lazy with my hands. C when the car is cold. And M if I'm really motivated. But most of the time S+ is plenty awesome enough for me.

I found this before in an earlier thread which has some info about different shift modes: "C mode means Controlled Efficiency, starts in 2nd gear, shifts sooner and smoother, defaults to that setting on start-up. S-mode starts in 1st gear, shifts 25% faster and higher RPM. S+- 30% faster shifting, will double clutch and blip the throttle on downshifting and will hold a gear to 6000 RPM if in a turn." Not sure this is 100% accurate, but I imagine it's close.

But yes, it's normal, rev matching because it thinks you want to really turn and burn. You're just teasing your ride when you do that...

AMGaintBAD

By tapping the throttle, I mean that I'm depressing it an inch or less only. I really think they should make it so that you have to press the throttle midway, for it to downshift so aggressively. And why is it only possible to downshift like that to 3rd? Why not 4th? If I want 4th, my foot has to remain on the gas pedal and then slowly squeeze it until 4th comes. Otherwise its only 3rd. I like the responsiveness of S+, as in higher shifts, and throttleblipping during braking. So C and S are not an option for me.

CarHopper

Well then quite frankly nothing is really an option for you. S+ is doing exactly what it is intended to do. It is always wanting to just go nuts, down shift aggressively, etc. It is designed so that a tap gets you downshifting like that because it is anticipating that the tap will become more than a tap getting you on the power earlier.

Seriously, give S mode a chance for a while. In normal driving situations it is ideal. There is your halfway pedal before a single downshift.

Otherwise, you're using M.

alexmtl

+1

S+ is meant for the track basically, maximum attack mode. If you don't want so aggressive downshifts, you should use S mode.

jordanaf

Absolutely true. By what you are doing, even the "inch or so" you are claiming you depress after letting off for a second(which is how that transmission mode is supposed to be triggered), the engine in S+ mode, thinks you are ready to drive more aggressively, wanting more power, and downshifts two gears to rev up the RPM's boosting the engine output.

Your car is totally fine and is doing what is programmed and intended. Enjoy driving!!

jrcart

The ECU thinks that 1 inch depression is a blip, it assumes you are going to be aggressive and is trying to anticipate your next move. Not sure what else can be said here.

AMGaintBAD

Thanks guys for all your comments, i'm happy now that i know everyone else has this too. I guess i'll learn not to tap on the throttle.

jordanaf

Additionally, just to fill you on the whole S+ feature, you will experience the same kind of results and "blip" upon heavy breaking. If you get stuck or your speed gets compromised and you have to get on the brake pedal firmly, you will notice heavy downshifting and multiple blips, depending on speed of course.

Just FYI. Thought we'd cover the whole transmission setting (S+) all together.

AMGaintBAD

Yes, I know about the rev matching during braking, and I absolutely love that. One of the best features of the entire car. Just wanted gas to be less sensitive so I don't accidentally get that surprise 2 gear downshift. Maybe the fact that I have a tune makes it worse.

roadtalontsi

most tunes ramp up the throttle pedal sensitivity and response. Although what you described is totally normal.