Transmission perfromance change after oil and filter change

[mitsi511]

Hello everyone,

I am new to this forum so please be gentle with me. I seem to have an issue that has developed since I had the first routine transmission service that was done in the middle of 2022. It was done by a local Indy Mercedes garage.
The problem is quite subtle and maybe nothing to do with the transmission at all. But since doing this service I have noticed that the car seems sluggish in comfort mode, at slow speeds or when just feathering the accelerator to maintain slow speeds. I also note that the change down in gear is at much lower revs (Nearly 1000revs before it changes down) and gets worse the further I drive.
When I bought the car when it was about 12months old, and until the transmission service last year, the car would effortlessly drive at any speed and was always in the right gear. Not so now. It almost feels like the engine is labouring and at risk of stalling. It just doesn't feel 'lively' and enjoyable to drive like it did before in comfort mode. In Sport and Sport+ modes it is still quick and responsive, but I don't tend to use these modes very often.

In January this year I took the car to another Indy Mercedes specialist (a bit further away), who did a check of the transmission using the XENTRY system and said that he could not find any fault, the transmission fluid level was correct and that a number of control unit software updates were carried out. A 'Standstill adaptation' was also done and I was asked to test the vehicle. If these updates did not rectify the problem it would be necessary to replace the transmission electro hydraulic controller (valve body) and park pawl costing lots of pounds. I decide not to take up their offer for obvious reasons.

Has anybody else had similar problems and if so what was done to rectify it.

Thanks for any help.

Mitsi

 

[markjay]

Welcome.

Is this an early W205 with the 7+ transmission, or a later car with the 9g transmission?

Also, did the car have the 'Dieselgate' recall done (engine management software update)?

 

[mitsi511]

Thank you markjay.

It is a 2017 W205 with the 9g transmission.
Sorry, but I am not sure what the diesel gate recall is. I never got a recall notice, however I have a XENTRY printout from the garage which shows a huge number of updates.

 

[markjay]

Thank you markjay.

It is a 2017 W205 with the 9g transmission.
Sorry, but I am not sure what the diesel gate recall is. I never got a recall notice, however I have a XENTRY printout from the garage which shows a huge number of updates.

I meant was the car serviced by an MB dealer recently, and if so have they updated the engine management software?

 

[mitsi511]

No it wasn’t serviced by a dealer recently.

 

[Bayleaf]

I could just be that the gearbox needs to relearn your driving style. The gearboxes are ZF and what's called adaptive. After a service they need to be basically run in for 100 mls or so without using kick down or sport mode, after that if you do a lot of spirited driving the box will learn to change up down etc in the higher rev range. If you drive more sedately the box will learn that pattern and change up / down at lower revs.
So I would go for a good run on roads that allow spirited driving eg dual carrigways/motorways etc and see if that brings it back round to what you had previously.

 

[mitsi511]

Thanks for the advice. Does the system continually learn, as I have done over 100 miles since the static adaptation.

 

[Bayleaf]

Yes is the answer to that, so give it a try and see what the result is, at the end of the day you've got nothing to loose appart from an extra couple of quids worth of fuel.

 

[mitsi511]

 

[Fastcar155]

I could just be that the gearbox needs to relearn your driving style. The gearboxes are ZF and what's called adaptive. After a service they need to be basically run in for 100 mls or so without using kick down or sport mode, after that if you do a lot of spirited driving the box will learn to change up down etc in the higher rev range. If you drive more sedately the box will learn that pattern and change up / down at lower revs.
So I would go for a good run on roads that allow spirited driving eg dual carrigways/motorways etc and see if that brings it back round to what you had previously.

Hi , I have learnt something today , did not know ZF made gearboxes for Mercedes

 

[Bayleaf]

You haven't learnt anything Boyband as my last post was partially incorrect. The gearboxes are made by MB in Stuttgart. However they are adaptive, so that part of the post still stands. I was lead to believe that they were ZF as most but not all cars with auto boxes use them even trucks these days. Sorry for the confusion.