Does anyone know if a dealer is able to reprogram the ECU on these newer cars so that it defaults to "S" at every start? If not, maybe an aftermarket tuner could do it?

 

The dealer cannot program it to default to S, at least in the US.

I've had a couple of instances where the transmission would not kick down, but it's definitely not a lag or turbo issue.

Personally, I've never found the turbo lag to be a problem. If you're making a left hand turn across traffic and turbo lag versus no turbo lag is the difference between an unsafe and a safe maneuver - the problem isn't with the powertrain in the car.

 

Sorry but just a bit confused here. Are you saying if you are cruising at 40 mph, "steady state" , the rpm at 40 mph is different if you started the drive with it in S vs E ? That would suggest that it shifted to say 4th in S, and 5th in E. That sounds right.

If you are cruising at 70 mph, flat road, there should be no difference in rpm whether in E of S. If in S, it should downshift more readily vs E mode.

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1) I agree with using S for an anticipated acceleration.

2) I don't understand why the "RPM's at speed are relatively high" ??

3) As far as I know, the only reason the owner's manual says to stop the car when switching between S and E (at least for cars w/o the special Agillity Package with magnetic shock fluid), is to cover their butts. As long as it is done when not accelerating, it's a very useful tool for the C250 owners so use it as needed.

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That's what I'm still struggling with as well. The only way this would happen would be if the S mode excluded the 7th gear from the program, but there is nothing about it in the 2012 owner's manual. All it says is that S mode starts in 1st gear and shifts up later.

 

All I can tell is this car will not downshift at slow speeds for almost 2 seconds, which is a long time. And there are many other people complaining about it.

The RPM's do change depending on S or E mode under 30 mph. At highway speed there is no change. At least in my car.

 

The rpm at most speeds in S are 3 to 5 hundred rpm higher mph to mph. In other words the rpm at a given mph will be 3 to 5 hundred higher. All the shift points in s are higher allowing the small turbo motor to run at a higher rpm. Once the car is at highway speed, in 7 gear and torque converter locked up the rpm in either e or s will be the same. If you shift from E to S while you are driving you will not see Any difference unless you either come to a stop or step down to cause the trans to downshift, once it does that the S program will be in place. In a nutshell I have found that driving in S allows the car to start off in first gear and raises all the shift points to a higher rpm that keeps the motor In a higher rpm range where a small turbo motor produces power. E just simply strangles the motor, just like starting a stick shift car I. 2nd gear instead of first and shifting at way too low rpm. I just wish it could be programmed to stay in S all the time. And yes, this is the only Benz I have ever owned that the E/S switch was something other than decoration.

 

I don't know anything mechanical. =( All I can comment about are my observations. I'll check try to check again, but my distinct recollection is that the RPMs once I reach cruising highway speed is are little less than 2000 in "E" (1900?) and a little more than 2000 in "S" (2500?).

Even when just cruising, the car feels significantly more "restless" in "S," and accelerating for passing is a smooth and linear affair (whereas it can be a little terrifying in "E".... And, yes, I'll admit that I'm probably cutting in front of a car during those times.... But I did the same thing in the C300 and my v6 Accord, and it was never a problem....).

And as for point #1, I usually switch over from "E" to "S" when at a full stop.

 

This is not typical of any other W204, but I guess you are assuming a special program for the C250 Turbo ? If it has a gear display, an owner should be able to anser that easily.

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I fully agree, assuming the 300 to 500 rpm difference (in bold) ie due to the S mode being in a lower gear.


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This is the only thing that would explain why the previous poster (alsyli) is seeing about 500 rpm higher engine speeds when cruising in S, if it is in fact what he is seeing and not just imagining things.

 

I can see the rpms being different at a low cruising speed, like 35mph, as the S mode will be holding onto a lower gear. But at a high cruising speed like 70mph on flat road, both S and E should be in the highest permitted gear. That would be 7th. You could manually go through the gears in S mode, and if you have another shift to D after 6th, you are in 7th gear.

And as I said before, I would feel confident to shift between S and E when you are cruising with a light load, as I have done for several years with no issues. The book bans this to prevent people from doing it when braking to a corner, or when aggressively driving ... not for fear of busting anything, except yout nose.

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Worth a read:

just-got-my-ecu-done-speed-tuning-usa

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E mode does indeed start the car off in 2nd gear. It also holds higher gears for better fuel economy, but as we are all way to familiar with, really takes a toll on the responsiveness.

S not only starts in first, but also holds lower gears (keeps rpm higher) for increased responsiveness and acceleration albeit at the cost of fuel economy.

It really is a shame that starting in 2010 (or possibly 2011, I could be mistaken) that MB made the car revert to "E" mode upon startup. In my 2009 if I shut my car off in S mode it remained in S mode at next startup. This has something to do with the EPA and fuel economy figures. It really is annoying and I wish MB would allow you to configure it yourself (I have complained in generationbenz and have been told its been forwarded to the engineers, yada yada yada, but no real results).

Needless to say that putting the car into "S" mode is part of my startup routine (seatbelt, etc). The car barely ever gets driven in "E" mode now. Also, I forgot who mentioned it, but you're right in that S mode doesn't shift into 7th gear on the highway until about 65+mph. I am not sure of the exact speed, but as the original poster suggested, if you're driving on the highway and want to see if you're in 6th or 7th gear in "S" mode then switch it into E with the same acceleration. If the RPM's drop you were in 6th and the car up shifted into 7th gear, if they remain the same then you were in 7th.

Some people hate Drive-by-wire electrical throttle sending system that MB has employed. However, there are many instances where I would go to accelerate and have to come to a quick stop and drive by wire saved me from possibly rear-ending another vehicle. You can see this system in action if you quickly tap the accelerator pedal and then let off 100%. You will notice that the rpm's rise (because the car downshifts) but the car doesn't actually lurch forward. If you were in a car that didn't use this system, your car would go lurching forward. The system pretty much tries to prevent inadvertent massive acceleration or mis-presses of the accelerator pedal. Not to mention that many various safety features (like automatic vehicle braking, etc, require the drive by wire system).

To end this long post, the Berger Motorsports tune and intake that I have installed has greatly helped out this delay (not sure which had more of an effect or if they both did as I installed them at the same time). "E" mode now feels almost like the stock "S" mode and "S" mode now feels very much like a truely aggressive sport mode. Additionally, for those who don't want to tune their vehicle, you can also look into SprintBooster. Many owners of the C300/C350 praise the sprintbooster for (nearly) getting rid of the lag.

As far as resetting the adaptive transmission settings, there is conflicting information on this and I have yet to come across official word. However, it is important to note that there may be a difference in the adaptive transmission and the driver profiles. Not only does the adaptive transmission develop driver profiles, but it also uses feedback from sensors in the transmission to (adaptively) alter shifting. Sensors such as various pressures, time it takes to shift, as well as vehicle age. It is possible that the dealership method via star diagnostics can only reset those parameters/functions. This would mean that the TCU accelerator reset method could reset the driver profile? Not sure if it was in my head or not, but the TCU reset method with the accelerator pedal seemed to increase responsiveness of my previous 2009 C300 when I tried it...

 

The RPMs do drop at speed when I switch from "S" to "E." It's not very pronounced, though. And I generally drive right around 65 MPH....

 

When S mode is activated - the transmission is always 1 gear lower than on E. If at 60mph it would be on 4th gear on E, on S it would have been 3rd and etc.

If you want to know which gear is engaged, you can switch to M while driving and you will see the gear that is engaged at that moment. By the way, I haven't seen anywhere in the manual that you cannot switch from E to S or M while the car is in motion...

And you cannot start the car on S just like you cannot turn off ECO permanently because of the global warming and the policy to lower the emissions. Actually, you cannot turn ECO off permanently on a Porsche Panamera Turbo S as well. If you want it to be turned off, you need to turn it off every time you start the car.

I find the E mode satisfying for daily driving and it leads to fuel economy.

 

I know it starts from a stop 1 gear lower in S mode (1st vs 2nd), but I have never heard of this "always" statement. I guess you could put it in manual 6th, like someone said, and see if it really is 1 gear difference.

I have always thought that for S mode the altered shift points (and shift speed) were due to an alternate shift map (load vs speed vs boost) programed in the TCU.

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cruising near 65 in the higher gears the rpm diff between gears is much less than at lower gears, so you could be seeing flip flopping between 6 and 7. And it's due to the higher shift point to 7th (from the map) in E.

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Indeed. The actual test is done on a mustang type dyno (vs dynojet), were the exact driving sequence is programed in. The test is done in E, and the EPA [Secretary Lisa Highgasprice Johnson] said the car should be driven as tested.

Is that during acceleration? Just comparing with the C300, which in E mode with lazy acceleration will be in 7th well before 65mph.

I've had/have 2 other turbo cars, 2.0L Saab and 1.3(really 2.6)L Rx7, both pre drive-by-wire. I modified the Saab so it took off with no lag and gobs of low-end torque. The Rx7 twin turbo starts off on one turbo, will all exh gasses going through it. I did a lot of intake/IC/exhaust mods for HPDE's. Point is in over 100K miles on the 2 cars, neither lurched forward dangerously. And I don't see why the C250 would be more likely to do this, if the lag were greatly reduced. Now there are some owners with the DC flash who report they now have no lag, so their input on this would be valuable.

If you are talking about the JB Juice Box, the before/aft dyno runs on their web site show very little change in initial delay, so perhaps it's the intake ???

Some have tried the SprintBooster and found it too agressive. No surprise because they just sell 1 model for all W204's, and the Turbo needs a custom SB tune.

First, I think the new $300 ecu flash from Silversprings-MD cured all the delay issues, so the concept of a TCU tune-up seems less real. I did mess with the TCU reset, even using a false WOT at about 3/4 pedal, and any improvement I think was more in my head than a reality. The Rx7 had a similar proceedure, except it was done with a voltmeter with the TPS pin-outs.

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Well, I have noticed that for sure - it is at least 1 gear lower than on E. If you are just cruising on S, you will notice that it will stay on higher revs than on E which means it uses lower gears, sacrificing the economy. Of course, the shift points and the shift speed should be different as well. Although I am not quite sure about the shift speed... has anyone noticed faster shifting on S?

 

Remember ~ I have posted previously.

"From the 722.9 technical training manual:

S (Sport) first gear start
C (Comfort) or E (Economy) second gear start, earlier upshifts and later down shifts. Auto default to E on Blue Efficiency models.

Note: Transmission will start in first gear if any of the following apply.
1st gear manually selected.
3/4 to full throttle applied from stationery start.
Engine cold (catalytic converter warm up)

Now - to precis the following: Certain high torque diesel models will pull away in first gear in both modes to protect the torque converter."

 

I was wrong about the "quicker" shifts. But I still find it hard to believe that if you had this car on wide open midwest roads, cruising at 90+ mph would be in 6th gear, if in S mode. Sure about that ?

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Rob Den Hartigh, 10-11-2012

MB C250 Throttle Response

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I'm in a unique position in that I've had two 2012 MB C250s over the past several months. Also, many of my coworkers drive the same car and we've all complained about the throttle lag that is described in this thread.

Both the C250s that I've had were identically equipped but the throttle response between the two couldn't be more different. The second one doesn't have any lag what so ever and is such a pleasure to drive.

It appears that MB has fixed the issue late in the 2012 model year

from:

c-class-w204-acceleration-problems-C250

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Well, it seems that cars with less miles are absolutely better than cars with more miles, a loaner with 300 miles was much better than a loaner with 2500 miles. and it is not related to 2012 or 13. Same programming in both years.

 

First, the torque converter locks up in all seven gears except when it's changing gears

And at 60 mph (just as an example) the trans will be in 7th gear regardless of S or E. It might not be at 40mph.

How many times does this have to be explained???