Zorq

My C450 was delivered Nov 9th, first day I drove it I brought it back to the dealer as the 1st to 2nd upshift sometimes jerks. It's not HARSH but it's noticeable and unpleasant.


I was able to replicate this almost every time by the following:


Accelerate in 1st gear from stop to about 2500-3000rpm
Let go of throttle and wait 0.5 sec and upshift to 2nd


Almost 90% of the time it will produce a jerk. I've tested the demo available at the dealership and it seems less noticeable or to the point that it doesn't exist.


I kept digging in further into this issue, and notice my C450 also jerks when downshift from 2 to 1 at VERY low speed (5-10km/h), not that you would do it. Unfortunately break in does not recommend downshifting at high rpms so I can't test that.


On the same demo, this issue does not exist as the shift from 2nd to 1st, at higher rpms are super smooth and rev matching well.


Anyone else have this issue? I'm not sure what I should do, I'm hoping after breaking in it will go away but I'm not sure on the chances of that. Will the tranny shifts smooth out as it breaks in? Appreciate all the feedbacks!

ManiacGT

What transmission is used on this model? 7g+ or 9g?

jakc

This is how it is on many C300s and probably C400s. Mine smoothed out significantly after 1k miles.

I think there was a firmware update to address that as well but since you just picked it up a week ago it should have it.

Congrats on the new car!

PeterUbers

Agreed with above

Give it 1000 miles, how many miles on it now

ManiacGT

Mine took around 4K miles to smooth out (7G+)

Glyn M Ruck

Yes ~ let it run in properly first. It should have the correct software flash. It's a new car. However some general points regarding driving. If you accelerate hard and whip your foot of the throttle and brake hard you can catch out the Torque Converter clutch as it's trying to lock up, causing a jolt. Smooth driving obviates this. I'm not saying you are driving poorly I'm just pointing this out. Secondly. There is a very large range change between 1st & second gear. On the 722.9 (7G) they finally changed the software so that when slowing down to a stop the transmission stays in second gear until the vehicle is stationary, then selects first for pull away. On the 722.9+ (7G Plus) they will likely change to this in a software update if it is truly changing down to first at low speed. The huge range change makes it difficult to do this smoothly. At least you have the issue logged with your dealer. Enjoy! nice car.

mvw

I've got a bit of weirdness too. Not sure how best to describe cause I'm not a car guy, but when I'm in sport+ mode and reduce speed quickly (e.g., when can in front is turning) and then try to accelerate quickly when it is out of the way, I sometimes get a lag which can be maybe a second before the acceleration kicks in, sort of leaving me flat footed for that bit of time when I press and nothing happens. Doesn't happen in comfort and less noticable in sport.

Assume normal?

ManiacGT

Normal, car is trying to get to the right gear and work out what the heck you're trying to do.

Zorq

Thanks for all the responses! I will keep an eye out and see if it'll smooth out after break in. I'm sitting at 600+ km right now.

PeterUbers

The first trip to the dealer they will tell you it's normal

The second trip they will reset adaptations and you can do this EASILY at home; and will tell you to give it 1000 miles

The third trip they will tell you it's normal AND reset the adaptations

The fourth trip they'll say could not replicate

https://mbworld.org/forums/e-class-w...50-4matic.html

Zorq

So I brought the car in and they said there isn't any software update, but the mechanic will reset the transmission adaptation. Mechanic told dealership it'll take the day to perform. I thought it only takes 5 minutes? Anyone has proper procedures to make the tranny adapt properly after resetting? Thanks!


So digging into this issue a little more seems there are documentation about mechanics hooking the car up to diagnostics and following a adaptation procedure to get it functioning properly? Does that mean I should not be trying to reset the adaptation doing the key to pos2, step on gas 5 seconds, key to pos0, release gas, wait 2 minute?

DapperStyle

If resetting via key position to 2 my experience with my W204 is to drive like a bat out of h3ll. Car is SUPER responsive for a while after, I used to do it before driving on some mountain backroads and by the time I was back in the city the car was a different animal.

parkwood

I have not had jerky changes in my 250d but just occassionally it seems reluctant to change up when in sport, usually in 3rd or 4th when it sticks around 2500 revs. Lifting the throttle does not help so usually i use the paddle change. It rarely spins above 2000 revs and at 132k it is only spinning at 1900 revs with the normal range 13 to 1500 revs.

The car was in the dealers today to swap to winter tyres and on arranging for the swap over we mentioned we thought the car needed the transmission update. Our contact who was the parts manager said they would need the car for the morning. Being france the garage is shut for lunch so we arrived to collect just before. In fact they had not done it as apparently it takes a long time to download from mercedes and they wanted the car for a full day.....the service manager asked if the problem was jerky gear changes so the problem is known. It is going in on the 30th and we will have a loan car. It seems the download goes direct to the transmission ecu. He also mentioned the will update the main software as well, mine is a april 2015 bremen build, or at least i think that is what he said as my french is passable not fluent!

PeterUbers

There is a custom adaptation they can do with their scantool and they can adjust the variances to a certain degree and also can determine if it's shifting outside of appropriate specs

They did this several times on both my 2014 e550's to no avail