722.9 Please help, I'm going nuts!

[Technoholic]

Hello all, please can someone help point me in the right direction otherwise I think I might go completely crazy.

I have a new to me CLS 350 CDI 2013, 61000 miles. had it a couple months now. It's had a couple minor issues that have been resolved but this lingering gearbox problem is not going away.

The problem is, from cold, the box has always been a little rough, changes not great and a bit of lurching sometimes, but overall, that part I can live with. It's the shift from 5-4 that is the problem. When cold, the shift is violent, like I've momentarily slammed on the brakes, that is what it feels like. It physically throws me forward for a split second. It's worse when the box is under load, so if it downshifts naturally when slowing, its a heavy jerk but if it downshifts because I've put my foot down a bit, or because I flick the paddle, then that's when I get the especially violent shift.

This problem goes away when the car warms up and there are no errors logged

What have I had done:

1. Software update on the gearbox and later on the whole car
2. Manual adaptation by MNB Specialist with Star while driving
3. Gearbox flush and new filter including TC drain
4. Car was remapped last week, overall much better but this problem is still as bad as ever
5. Car is with Star of Reading right now to investigate again, but they've said I need to manually learn the adaptations from cold by letting the car downshift itself till it stops and repeat a couple times (is this an actual MB method to learn proper shifting?)

All specialists (it's been to 4 or 5 now) have said that they either can't fault the box, or that it's normal to have that level of shift jerk but I can't help think that they aren't experiencing the problem fully due to not driving it in a way that highlights how bad it can be.

This problem is bad enough to make me not want to drive the car as it's really disconcerting when it happens, it really feels like I've hit something. So what is my next action here? I know there are various other adaptation processes for the TC and so on in Star but I don't know if these were done with the previous manual adaptation or whether it's even worth pursuing that. It's costing me a lot of money to investigate this and I don't want to keep throwing money at it, id rather know what I need to pay to get it sorted.

If anyone has any ideas, I'd be really grateful to hear, I really want to get this sorted out!

Thanks

 

[LostKiwi]

If anyone can sort it Ian at Star can (assuming you mean Star Motor Services in Caversham).

 

[Technoholic]

If anyone can sort it Ian at Star can (assuming you mean Star Motor Services in Caversham).

Yeah it's with them but this morning they are telling me it's not bad enough to do anything more than this manual adaption process mentioned above?

 

[LostKiwi]

I'd not want to second guess Ian. He's probably one of the best indys around (along with Cole @ MBS and Steve @ Avantgarde). I wouldn't go anywhere else other than one of those three if I had a difficult problem.
The 722.9 is known for hard shifts when cold.

 

[Technoholic]

I have heard that but it just seems excessive.

It's been to MBS too, they did the manual adaptation, Star are going to carry out this procedure they talked about for me this afternoon so maybe that will help, I don't know

 

[John Laidlaw]

Yup, Like LK says - Star, Avantgarde, MBS, AMF and RH up in York are the ‘go tos’ so if they don’t know, no-one does (there are also MD Motorcare and MB Tech local to me I trust...)

 

[Technoholic]

Well I am happy to trust these guys, If I have to live with it then fine but it's certainly not what I'd consider within the normal range of jerky shifts. I can't imagine it came out the factory like this, so if there really is nothing to be done then I'll have to leave it instead of throwing even more money at it.

 

[Srdl]

You are in good hands with Star and MBS but I didn’t ever experience anything like that in 67k miles with my 722.9. If it only does it when cold, is there any way you can drive the car with someone from Star on board to demonstrate to them what is happening and get their view on whether it’s normal? I appreciate the logistics of doing that may be a problem.

 

[Technoholic]

yeah logistics is the problem, need to be there first thing to do that and that's difficult with work. But Star have said they have experienced it but maybe not as badly as I have, I've told them how to replicate it so hopefully it will be detected

 

[V6Matty]

The re learning process Ian told you about is the correct one for STAR, also the upshift point are only needed for 1-2 2-3 and 3-4,
As the others have said the early 722.9 was known for harsh shifts, some much worse than others, mine can be bad but I noticed if I actually drive the car hard the next time I get in they aren’t nearly as bad (that said mine isn’t bad most of the time).

 

[Technoholic]

The re learning process Ian told you about is the correct one for STAR, also the upshift point are only needed for 1-2 2-3 and 3-4,
As the others have said the early 722.9 was known for harsh shifts, some much worse than others, mine can be bad but I noticed if I actually drive the car hard the next time I get in they aren’t nearly as bad (that said mine isn’t bad most of the time).

So do you mean the relearning procedure needs star to do it? Because they told me to take the car away and do it myself. Specifically, get up to 5th, then let the car naturally slow down shifting through the gears downwards until it stops and do it again.

 

[V6Matty]

So do you mean the relearning procedure needs star to do it? Because they told me to take the car away and do it myself. Specifically, get up to 5th, then let the car naturally slow down shifting through the gears downwards until it stops and do it again.

Sorry, I wasn’t clear with my reply, what I meant was that is the process that STAR dictates for learning the downshifts, it doesn’t actually need to be plugged in at the time,

 

[Technoholic]

I see, so it can be done at anytime basically? Obviously I need to adjust my cold shifting so I would do it first thing in the morning if necessary. Do you know where I can find detailed instructions about the procedure?

 

[V6Matty]

Yes really that simple and can be done anytime. Just need to find somewhere nice and quiet to allow you to coast to a standstill from 5th gear, if you have paddles, lock the car to 5th and then let it do the downshifting while you coast to a stop

 

[Technoholic]

and what do you do when it gets down to 1st? Apply brakes and start again?

 

[malcolm E53 AMG]

If all else fails this might help!

https://www.bing.com/videos/search?...A56A42781F44A33A83ACA56A42781F44A33&FORM=VIRE

 

[Technoholic]

still struggling to find the documentation for the coasting learning procedure above, I'd like to know the specific details of exactly what to do when it reaches 1st gear, when to brake etc, what to do when I need to move off again and so on, so I know I'm doing it right but the WIS for the 722.9 that I can find only talks about adaptations via Star which I obviously can't do.

 

[V6Matty]

Let’s ask the expert @star , could you let the OP know how he can do the downshift learning himself

 

[V6Matty]

and what do you do when it gets down to 1st? Apply brakes and start again?

Yes

 

[Uncle Benz]

If adaptation won't fix it, the operation of multidisc brake B2 is faulty. It could be the solenoid that switches that brake, but you can't buy solenoids for the 7G separately from the valve chest sadly. The B2 brake is locked for gears 1,2,3 and 4. It unlocks for 5 and remains unlocked for 6 and 7. It only re-engages when 5-4 down change happens.