Did some searching, not sure I got a good answer yet, so I'll throw it out to the group:

Situation:
Over the weekend I drove the car a bit in sport mode- it's been nice here in Chicago- finally- and was zipping around enjoying the car with the top down. This was the first time really I have driven it for any length of time in this mode, honestly...I forget it has it. Tuesday evening I drove down the interstate (in Econ mode), hit the usual high speeds running along 94, then got off onto a main road after about 20 minutes of driving. The road was stop and go for a bit right after I got off and I noticed that when stopping, then crawling forward slowly there would be a "jerk" (not switching gears, this was in second in Econ). This kept happening until traffic sped up, car shifts with no issues. It does have a bit of a slight- and I mean slight- hard shift from 3 to 2 on occasion. Anyway, this was the first I'd experienced this. Car appears to be shifting just fine with "normal" driving, it was the stop and go, which I don't normally hit, where this popped up. I am going to see if I can replicate this issue today at some point.

Other details:
Transmission fluid and filter done last June at 70k (car has 73k on it now)
Car is driven mostly locally, sometimes only short distances, but I make sure it gets warmed up driving around before going home. I work from home, so it does not get exercised every day.
Have an appointment with a trusted indy here that specializes in MB in the area to take a look next week.

Unfortunately, I would like to drive the car this weekend out to see my parents (60th wedding anniv) but am thinking to not tempt fate. Ironically, my W211 E320 CDI is ALSO looking like it needs tranny work (likely the conductor plate issue). I have another vehicle I can take, so they can both sit if needed.

Anyone have this type of issue pop up? Originally I thought the fluid might be low and maybe foamed up or something at the high speeds, but it was just changed. I understand there really is no way to check the level without the special dipstick and removing the "do not remove" cap (unless that is on a different transmission, but I read it is on all the MB 7-speeds). I haven't yet checked for a leak.

Any comments, insights, etc. appreciated.

Thanks!

John

 

Almost sounds like a drivability issue related to engine, but hard to tell.

You could try to reset the adaptive shifting (see link below). There’s really no downside to this.

With the Keyless Go button inserted:
1) Keep your foot off the brake during the whole procedure
2) press the Keyless Go Start button once
3) press the accelerator to the floor and hold for 10 seconds
4) press the Keyless Go Start button twice to turn off the ignition
5) release the gas pedal
6) Wait at least two minutes before starting the car.

With Key Inserted in ignition:
1) ignition switch to position 1
2) push the gas pedal to the floor and hold for 10 seconds
3) turn the ignition switch to the off (0) position
4) release the gas pedal
5) wait at least two minutes before starting the car.

Good Luck!

https://www.mercedesmedic.com/reset-...-instructions/

 

I was going to try that this morning...appreciate the steps/info! I actually just did the reset on my E320 about an hour ago just to see...

Curious as to what could cause this related to the engine itself....I'm going to go over it in more detail today. No codes or CEL at this point.

Thanks a ton for responding!

John

 

It's hard to tell without more info, but the ECU and TCU do work together, so it's possible it is an adaptation thing.
CEL probably won't come on unless it's pretty serious, or emissions equipment failure.
Many scanners wont pick up all the codes if they are chassis or transmission related. It really depends on the scanner.
If you have your car scanned with XENTRY, you might be surprised the codes it picks up vs other scanners.

Good Luck

 

Figured as much on the CEL...yes I have a basic scanner, no Xentry at this point yet. With three MBs now it needs to happen, as my intention is to wrench on these babies from time to time. I had the VAG-COM software for my Audis way back and you are so right, stored codes are all over that don't get picked up by other scanners (and needed to reset the electronic parking brake on an S8 among other things!) I'll start looking at SDS/Xentry options. I appreciate your info and guidance CRC! Thanks for the time!

John

 

I think this is nothing. We never ever drove our SL's in anything but Sport/Sport+ mode, so part of the shift pattern is more aggressive, including downshifts. For me this was desirable. The transmission will quick relearn the slow shifts from driving in heavier traffic (I call that lazy shifting). Resetting the transmission will actually switch to the more responsive default mode.

 

Noted. I reset it and am going to take it on the exact same route again and see if I can get it to do it again. Hopefully it IS nothing!

 

With that many cars it will pay for itself many times over.
As you know from your Audi, It’s really difficult to work on these cars without the factory diagnostic systems. There are other scanners, but they can be cryptic to decipher. XENTRY coupled with the WIS used to isolate and test individual components is indispensable. You’re flying blind without it. It’s just the nature of cars now and for the foreseeable future..

 

This is the reason to never drive in Econ Mode.

 

HA! Griza I agree...in my 991 911 I was always in "sport" on the PDK. The SL "sport" is a little different, but you have a point. And yes, CRC, agreed you are poking around in the dark without the proper tools, for sure. At the very least, you are able to give the mechanic some direction if you decide to not do the work yourself.

Update: I did do the reset yesterday morning and took the car out later that afternoon out on the interstate, ran it up to 80-85 for a while, got off and tried to replicate the issue (turned it back and forth in sport, etc as well). It did not repeat the jerking while crawling around...I probably looked like a weirdo in the Costco parking lot. I am going to take it on my 200 mile trip today- almost all interstate- and see how it does. (I did the reset on the E320 as well and it seems to be ok too for the moment...go figure). Maybe the transmission program just needed to be cleared out...

Will keep an eye on it, however now I'm super sensitive about any transmission jerks/jolts!

Thanks all,

John

 

Sounds like a win. I always like to reset adaptation after an ATF change. Not sure how long ago (mileage wise) you had the fluid changed, but it obviously played a part in what you were feeling. LOL! Not advocating not changing ATF, but sometimes you can change ATF and it makes drivability issues worse 😕 New ATF can slightly change the characteristics of the friction properties and how it behaves with the transmission. Sometimes you need to make adjustments in XENTRY to compensate.

 

You have described poor shifting which is normal for MB transmissions. MB transmissions are not good.

There is no transmission reset except for modifying adaptations in XENTRY. This is the only way.

Anything posted regarding “transmission reset” on car sites like this one in the past 20 years is urban legend. The same “reset procedure” has been posted and reposted for every car brand under the sun. It ain’t real. It’s a snipe hunt. A left-handed smokeshifter.

 

LOL 😂
Sorry I really don’t have a lot of time to respond. But usually this kind of statements comes from inexperienced folks who have never used XENTRY to control settings/adaptations (nor compare settings before and after reset, settings DO change.). I suggest you might want to read a few technical articles on the matter. Not from internet forums, but rather trusted educational resources and experienced industry professionals. I really do try to focus my time here on maintenance issues and solutions rather than responding to disgruntled brand crucification posts.

Do you have a problem on an R231 I can help with?

 

I have experienced what you describe with my 2014 C350, which uses the same transmission. Usually it's a "hard" downshift at slow speeds coming into the neighborhood.

There is a more sophisticated adaptation process that requires two German guys in lab coats, one driving and one in the back seat, with their XENTRY laptop. The guy with the laptop (back seat) fiddles with his computer while the driver drives around the parking lot. When done, everything works except the credit limit on your credit card. Remember, they MUST be German and they MUST be wearing lab coats.

 

Yes, and the most important thing about these two guys in lab coats is that they are using XENTRY to modify adaptations. There is no other way to affect shifting, except for replacing fluid, friction elements or hydraulic elements (valves, solenoids, sensors).

Anything else is urban legend.

 

Apparently, the older 5-speed trannies were made by Chrysler (or vice versa) and there was a company in Louisiana (I believe) that physically modified the gear channels (or something like that) and other components to improve the sluggish shifting of the 5-speeds.

I think this is a video discussing it.

 

My guess is the German guys are not smiling either….

When I took the car into my indy for an oil change for the SL they scanned for codes and drove the car…found no issues, so I dunno. It does still shift a bit hard 3-2, but it’s been doing that since I’ve had it. I asked if there was any way to reset the transmission learning and they weren’t aware of any way other than Xentry either. He was a tech for the local MB dealership for decades and knows all the tricks…snake oil or not, my feeling is it can’t hurt, so whatever…

Anyway, keeping an eye on it. I consider taking it in for an oil change and leaving with just an oil change a win! 😁

John

 

Folks, MB boxes are bad. No codes will be thrown when a bad-shifting box does what it was designed and manufactured to do - shift badly.

The only things that may, or may not, have a meaningful effect on an MB box:
- new fluid and filter
- new conductor plate (mechatronic unit with solenoid valves and sensors)
- new oil pump
- new friction plates
- reset adaptations in XENTRY (two German guys in lab coats)

Anything else is myth and urban legend.

 

Let me try to help and add some value here.
It's fairly easy to confirm, for those who actually use XENTRY, that parts of the TCU and ECU "marriage" are reset by comparing settings before and after the reset procedure.

End users can be quick to dismiss this procedure and say it makes no difference or a "myth" in solving their drivability complaints because it won't solve any underlying transmission issues that are beyond the scope of what changes will be relearned. The transmission just relearns "the same" drivability issues. It is never intended to be any kind of cure for underlying issues that need permanent modification in XENTRY.

There is a reason we reset this part of the adaptive learning:
Diagnosing drivability issues is a systematic procedure of making changes, testing and making more changes. Progressing systematically from least invasive, to more invasive and labor consuming.

Since we don't know the cars history. We don't know of any previous drivability issues, repairs (if the car was driven during this process) or any low voltage conditions which may have affected the flash memory settings.

So logically, the first step in trying to diagnose end user drivability issues (over the internet especially) is try that reset any flash memory setting related to that system/vehicle first, especially someone with limited access to diagnostic software and tooling. It's a NO COST possible fix on the off chance that some previous "corruption" existed. And one I would do before, and after any transmission service. We call that a "no-brainer"

If you use XENTRY extensively, you will understand cars learn "bad" habits all the time.
As an example, many times you hook up XENTRY to a new MB with drivability issues. The first step is to record stored codes, and then reset them all. From there, you can make a proper diagnosis AFTER you've re-driven the car. Many of the stored codes will be FALSE codes from previous events that may be unrelated, or were what was deemed outside of operating parameters by one of the components. After another scan, the stored codes are will be REAL codes and you can start trying to track down whatever issue is actually present.

Maybe it helps to put it in terms people may understand better: It is akin to force quitting an application vs a complete reboot of your PC. You're resetting only a small part of the current running system configuration.


Hope this helps and good luck!

 

​​​​@chassis Is this part of your signature block?

(Remember, legends are not always false!)

 

I am late to this thread but my CLS400 with same drivetrain does this every once in a blue moon. A transmission reset fixes it, it's just adaptation for more aggressive shift. Of course, when you go back into ECO, you don't want that roughness anymore and can definitely feel it.