Hello,

I notice when I got my car in up down hills, hard shifting from 3rd to 2nd as someone push me from the rear, I read many threads as it is common issue. Is there any fix or it is better to change transmission fluid and filter. Or is it adaptation procedure that take too much time so how I can reset my transmission.
My car 128k miles and no idea if tranny fluid changed before even it was serviced every 10k miles.
My dealer need 500$ for tranny fluid replacement.
Thanks in advance.

 

I'm not sure if I can help you, but I will offer some insight.

Does this occur as you begin to accelerate, brake, etc., or merely when coasting?
I no longer have my W212 and don't remember this type of thing happening on hills. However I recall that often when I was coasting to a stop on a red light and if the light turned green and I resumed accelerating before coming to a complete stop, if would shift/jerk very hard. The only solution I ever found was to learn to ease in the accelerator very slowly in these situations to ensure a smooth upshift.

 

It is happening when moving slowly so the tranny downshift to 2nd gear or when you going uphill as the speed reduced and the tranny downshift, event if I am accelerating and use paddle shift to downshift from 3 to 2nd it will occur, specially in cold weather and in hills above 600 meter sea level as in my town about 150 m and warmer I didn't notice it but I will test it tomorrow when I go back to my home.

 

Tranny has to have good ATF to operate normally. When the fluid ages it tends to become more thin and loaded with abrasive particulates. It just keeps getting thinner and less lubricating once burned.

Automating smooth shifts requires precise conditions. The shafts RPM need to nearly match to limit a more or less severe bang when the clutch pack finally grabs solid.

An awesome Siemens module is in charge of managing the valve body controls. It sports a state of the art software to perform best in most conditions.
You can trust this gear box is great - It is the surroundings that are causing it to misbehave.

You can train the shift adaptations at will to lessen abrupt shifts, the timing issues will remain... go test drive on a flat unchallenging road.

> Seemless SMOOTH vs. goofy BANGS:
You can rebuild the transmission or bolt in a low mileage unit, the shifts will remain similars.
The mechanicals that are far from bad, it's the control network that's built to be amazing.

When the shifts are delayed by CAN latencies, the ECU/TCU is unable to cooperate for seemless shifts.

Ever since my car was new, the 722.9 shifts were either average or poor, 4th/3rd downshifts banged frequently to various degrees.
By 20kMi I was used to the rocky KIA like experience. I understood the banging was fairly consistent but didn't know what could be done to a low mileage vehicle.

Fast forward a little... after I fixed my Steering Control module and EIS, out of the blue my tranny begun to shift up or down all gears extremely fast like a machine gun. That helped me realize the prior confusion my tranny was in, always goofy late.

Now my tranny is always in the perfect gear for speeding up or costing. I can slow down for red light and accelerate when it turns green.

I am not even sure the SCM is directly on the same CAN as tranny. They definitely have the interdependence necessary to make things good or bad.

At that point it is clear that defective solderless connections are ruining the ownership of many.

 

Thanks for your explanation.

From that day till now I didn't feel it at all and the shifts smooth and as expected with E mode and same for S mode. So this behave I felt it twice when I visit my wife parents which there town 900 m above sea level while my town only 100m and in both visit temperature there below 12C while in my village from day I bought the car temp above 15C. I try to reproduce the issue by downshift from 3 to 2 it didn't while I did that in that town even after 5 min from startup and the car moving straight and down it happened.

In couple of days I may got the registration paper of the car so I can book the service with dealer for all fluid replacement and coolant.

My question is the air temperature or hilly mountain affect tranny shifting and what is the cause of that.

Thanks in advance.

 

Yes engine Temperature, ATF Temp., Intake Air Temp., Barometric pressure along with 200 other parameters (engine Load, Throttle position, ... Adaptations, historical shifts) all affect shift execution.

Tranny are the most advanced assembly of this vehicle ahead of the combustion engine. Anytime the tranny computes an unfit solution, you get a poor shift.

Try holding the gas pedal steady a little more so tranny gets a chance to catch-up with the engine on what you want. Machine understanding is mostly limited by its sensors.

 

This was happening to me (hard downshift during deceleration or downshifting as it was going uphill) and it was a combination of a worn transmission mount as well as rear brakes. This began happening after the 50K mile transmission service.

 

This has happened when the temperature is between 40-55 degrees and the car is cold ever since I purchased it at 28K (now 55K). I took it to the dealer while under warranty and couldn't reproduce. It's very slight and just something I live with.

My 2007 bluetec had a much harsher 2-1 downshift when cold that was fixed by a firmware upgrade. Unfortunately that same upgrade removed the differences between comfort and sport mode. Not like having a transmissions hold a rev on a 3900 RPM red line does much on a diesel anyways, but it was kind of cool.

 

Now a day it is hotter in my village so its rarely can facing this issue, so I will monitor it more and more.

I have some question after 2 months riding this new car, I will share my feelings during driving and hope that is normal or something to do:

All the below using E mode.

1. When driving the car in some cases for example you are moving 35 MPH(5th gear) then you use brake for a while then moving with light press acceleration, I feel that the car not responding or very slow acceleration until you push more bit at pedal it will downshift then move faster.
2. Sometime I feel that when you try to pass a car infront and you push the pedal it will take 2-3 seconds to downshift and move faster.
3. If you are at 5,6,7 gear at rpm around 1k, I feel that the car has no much power with light acceleration so you need to push more acceleration to extract the power.
In S mode I didn't use it to much to compare if it is better feeling or not since most of time forget to set S mode.

As I am coming from W220 M112 engine with 722.6 tranny so is my feelings is normal or I need to reset transmission adaptation as didn't do reset adaptation after buy it.

 

Your feedback experience is no longer about nasty shifts but delayed response in partial throttle.

Most drivers under these conditions simply rev-up RPM to get plenty of power output or use S-mode to keep revs up slightly above normal.

It's all and the same: engine and tranny are not in perfect sync. If they were car would happily drive up hills at 1,200.RPM with plenty of torque in reserve on the same high gear.

Tranny ratio affects combustion engine and vice versa. To deliver smooth accelerations, the pair of controllers need to match target efforts like twin brothers.

In my book, this driveability issue is not caused by seasonal temperatures.

 

Yup for sure not related to season temperature but do I need to reset adaptation or change the way for accelerating to achieve sync.

 

Nop, you do not!

That is simply mis-guided conception that temporarily shuffle the cards.

The TCU ability to learn from historical data is designed to help enhance shift performance... not the other way around to hurt it.

Let me re-read your thread to see what's going down and free advice on exit tips...
you have a keen understanding of shift expectations and how things should happen and do not.
A large number of drivers are equally confused by this poor tranny performance. I was one of them not long ago.


Touring the UK: London doorway


List of favorite mis-conceptions :

Resetting the ECU (does not) fixes lean fuel trims and poor throttle response.

Rebooting whole car (does not) fixes soft-crashed SAM's.

Resetting tranny (does not) fixes poor shifts.

 

Get your tranny oil and filter replaced and if your torque converter has the drain hole, that is even better.
Tranny oil gets hot very very slow, even for me in 33-34C ambient temperature.
So if you tranny oil is too old or not as good as new, when it is still cold you get the worst result.

I do not ever get jerk on my tranny since day 1. But when I bought it at 4 years old and albeit only at 10,000KM, 2 months or so later a tranny oil change made the gear change response better.
4 years is way too OLD for any oil with such duty like a tranny does. Time age oil too, not only distance travelled.
Also to note, coldest ever ambient temperature of my car is at 18C only if I go to the mountain. Otherwise 33-34C ambient temperature is my all year round city (sea level ) temperature.

 

As I said I don't have idea when last time tranny oil replaced but I will schedule it next month at the dealer shop. Nowadays it is end of spring and the summer is coming so lowest temperature will be 20 to 26C at nights and above 32C in days. It will not be easy to check shifting but throttle response will be check after oil change.
I will keep this tranny to understand my drives as no rainy days so it will be mixed S or E mode and get good comparison between them.
Thanks for you advices.

 

100% Get the oil drained and filter changed, we did my partners 2014 E350 Wagon yesterday and replaced the rear tranny mount and now its smooth as silk to drive, a MASSIVE difference to how she runs now.

 

Good advice, how do you tell if the mounts are bad too, do you push it and see if there is play? Does that have to be done when it is off the vehicle or you can just see it right away?

 

Best to do this on a proper hoist/lift and have a gearbox jack handy.

We undid all the circled bolts with the box supported, the pan was back on with new filter and oil BEFORE we did the rear mount swap.

The rear mount has the red X through it.

www.rockauto.com has them cheap.

E350 722.9 V6 Rear Transmission Mount

With a tyre lever or similar you can push the tail end of the box up and see if the mount is worn and sagging, this one was, we think it was causing the tail shaft to go out of alignment and making a bad strobing vibration in the car under load at around 1800-3000 RPM.

The oil level was very low and black with a weird smell.

New oil and flush out with carby cleaner along with new rear mount and she's like now again.

 

Lovely appreciate the insight thanks again

 

It's nice to see it paid what you did to your car
Besides, look at the size of that thing, it's massive

 

Yup, that's a big boy for sure.

 

> STANDARD :
Fresh clean ATF is the first requirement for a chance to get normal shifts. Keep your ATF around 40 to 50kMi is recommended based on driving style and aging.

A good tranny mount is also required to smooth out shifts and let TCU learn shift-points with precision. This single rubber mount bears the weight of the gearbox at all time. It's responsible for driving vibrations and aditional bearing wear of prop-shaft holder and transfer case pinion.
​​​
Once you have done all that hopefully shift qualities are better... dealers can retrain shift adaptations using Xentry.

The Valvebody is actuated with PWM solenoids protected by fine mesh screens... when all plugged up with clutch material then slow pressure build-up cause delayed shifts. That's when a "conductor plate" replacement shows up on the $4k repair.
Don't abuse a tranny with poor shifts!


> TRICKS don't make up for black ATF:
If none of standard maintenance brings joy, there are advanced questionable tricks to bring timings & performance to top shape.

Timing tricks are geared towards latency reduction.
The TCU learns historical shifts so shifts must be extremely reproduceable with very limited variance.

The goal is to loose most variance out of TCU work.
I have showed my W212 was plagued with CAN delay issues affecting sync of ECU-TCU.

Multiple electronic factors introduce delays in this jig. It is sad that MB engineers did not have ability to ensure good shift performance.

The timing performance of CAN is pretty elastic and this is EXACTLY the opposite of what we want for great shifts.


> Improvements:
Currently the ECU-TCU sync is limited to a "best effort" performance when in fact it requires a near "real time" performance.... so the average Mercedes-Bosch computers are built with counter performance factors.

While it works, it's a 180-degree departure away from "the Best or Nothing" MB marketing.

We can try to rework unecessary sources of latencies. This morning I got personal with Front-SAM and can report it's a Bosch unit serving the Bosch ECU
👍

 

Informative, thank you : )