Tareck J

Hello everyone!

I drive a 130,000 km s500 amg plus package from the UAE dealership ( 2nd owner), and I've been noticing a very slow response in acceleration and downshifting on the highway - even flat roads - when i need to pick up speed.
The issue has been there for a while bit i can't reason that it's the way this car actually drives. Putting it in C mode makes things a tiny bit better and smoother. Otherwise, i have to floor it till it clicks in order to get good acceleration (which ends up very brutal!) - with a noticeable high rpm before it actually pushes forward.
i have also tried manually downshifting, but the delay was still there. The car won't respond instantly.

Using a Star with development mode:

Absolutely no fault codes on Star
Tried the manual ECU / TCU reset
Tried resetting the transmission with Star
Tried playing with the parameters of the ECU on Star to cancel the adaptive learning of the transmission (following a video posted by someone here)

Nothing worked

It feels like the car pedal has a mind of its own

​​​​​​Please help before i end up selling this otherwise amazing vehicle

Tareck J

Appreciating advice
Anyone?

jackaleman

i would take it to one of the many mercedes specialists in your area? (sharjah - behind al futtain al wahda street)

I think your gas pedal sensor is the issue. Good luck bro
https://www.google.com/search?q=w221...#imgrc=_&vet=1

tzj00

Thank you for your response!
Actually I have moved this car to Beirut (Lebanon), so i have to rely on local shops here - as our only dealer is crazy expensive!

I believe i have a reason to ommit the pedal sensor as a culprit, as i usually hear some minor knocking sometimes before it finally downshifts abruptly. Mind you it doesn't always happen. I notice that when i go harsh on the pedal once, it becomes a tiny bit more responsive.

So maybe it's a transmission issue?

Moreover, when i am stopped but in D, and switch from S to C mode, i get a touch shift from 1st to 2nd gear as it changes modes.

Any advice?

Thanks!

jackaleman

Ahh yes, gargour, very expensive. I lived in Broumanna for 6 months.

I experienced the same symptoms on my G class, but without any mechanical noises. I felt as if my coil packs were clicking, like an electrical popping noise. Maybe that's what you mean by knocking sounds?
Try to find an electrician capable of Mercedes diagnosis, or if you could swap a pedal sensor with a known working one?

What area are you in? I'll help to find a mechanic nearby hopefully. Q

tzj00

Glad to know you were a neighbour!
Done from lebanon for good?

And thank you for the content.. i believe it could be a lag in the transmission, as i also notice a tiny delay when i manually downshift (sometimes)
I am not far from broummana - aley - so any good mechanic or specialist that you would trust is welcome as a recommendation.
I also have a bunch of little repairs to follow up, but need a trustworthy workshop.

All the best!