kimeran

Hi guys

Been struggling with this for a while now, and only gets more frustrating.

So I have a 2011 Pre-LCI C63.
When cruising along, I leave the gearbox in C, and manually change up at around 1500rpm (feel it unnecessary to let it go to 2000rpm).
Through all the gears, its fine, but on the odd occasion when changing from 4th to 5th at 1500rpm, the car will rev up to like 2500rpm and then change to 5th.
Basically like its slipping and then changes.

Taken the car to Merc a thousand times, and of course it works perfectly fine when driving in it with them.
Scanned it and there are no errors.

Any idea on what it can be?

roadtalontsi

a flare up like that is going to be an internal problem. Be it a sticking check valve or solenoid in the valve body caused by a part failure or trash clogging it - or a failing clutch pack set. sorry man i know thats not what you want to hear.

Alex.currie44

Have you tried an ECU reset?
Door closed, key in the ignition turned to first detente ( no start), slowly press accelerator to the floor and hold for 20 sec. Turn off key while holding accelerator on the floor. Sit tight for 2-3 minutes. Do not open the door.
I have fixed more than one issue with this in no less that 3 recent cars.
It's like chicken soup. It might not help but it won't hurt to try it.

Phil Chow

I believe if you do a full battery reset, it also resets the shift patterns on the TCU also.

Can give that a try.

kimeran

I've tried both guys, no luck

So if it is an internal problem, what can I do? Because Merc refuses to do anything unless there is an error code

Alex.currie44

Well it is out of warranty. Do you have a competent indy transmission shop you can talk to?

CDM Motorsports

its def an internal problem. Bring it to an independent shop that does transmissions. Most dealerships dont mess with internal issues on trans, they just sell you a new one.

kimeran

The car is still under motorplan, but Merc refuses to do anything unless there's error codes