Gearbox fault 2007 280CDi estate

[StevieB69]

Hi Guys, hoping someone can give me a clue where to go with the following fault on my 151k miles 2007 280CDi with the 7 speed transmission.
Basically I was beginning to feel that the auto was getting a bit sluggish and maybe a bit rough feeling so I booked it into the local indie MERX Stoke for a fluid & filter change. When I picked it up it was still warm and drove smoothly the 5 miles home where it was parked until the following day.
Where I live I drive about 300 yards off the drive before coming to a junction so the car just about manages to change up to 2nd before having to change back to 1st at the junction. So the following morning when I approached the junction there was a harsh "snatch" from the box and the car went into limp mode.Experimenting over the weekend I found that when the car is cold this occurred every time but if I did the manual gearbox adaptation reset before starting the car the fault did not manifest. I've taken the car back to MERX thinking that it was probably some deeper setting that needed resetting with STAR but having left the car overnight twice they have not seen any fault codes or experienced the fault themselves.
Their best guess is that it might be the (I think this is what it's called) freewheel clutch.
To me it feels like an electronic fault due to it's intermittent nature and the fact that I've found a work around. Anyone got any ideas?
Thanks in advance for any info you can share.
Cheers
Steve

 

[StevieB69]

Hi All,
Car has finally produced a DTC, P2015, the dreaded swirl port. Does this/will this/can this contribute to the harsh down shifts I am experiencing from 2-1 or 3-2 when it's cold?
If I do the resistor mod is it likely to improve the shift situation?
Any help greatly appreciated.
Thanks
Steve

 

[OneForTheRoad]

Could be nothing at all wrong with the gearbox. What your feeling is the engine putting itself and the gearbox into limp mode .

 

[BTB 500]

Seems a big coincidence that this problem came up immediately after the fluid & filter change?

 

[StevieB69]

Hi BTB50, it's not exactly new, I've owned the car 8 years and have never been totally happy with the cold shifts, once it's warm it's perfect.
I've seen plenty of posts with people complaining about the harsh down shifts on these boxes, it's like some unseen force suddenly stamps on the brakes at the last second of downshift, but I've never seen any with a categoric diagnosis / fix.
It's a shame as it's really the only thing that puts me off another automatic Merc.

 

[BTB 500]

But it sounded like yours was behaving differently immediately after the work you had done? We have a 2007 C230 with the same gearbox and it's super-smooth, although it has done less miles (96k) and is petrol rather than diesel. We have two other automatic Mercs but they have the older 5-speed box.

 

[GordonTarling]

Have you tried putting the gearbox in 'C' mode or whatever it's called on your car? Causes it to pull away in 2nd gear unless you use the kickdown switch. Gives a smoother ride. In my experience, most of these MB auto boxes are a bit 'lumpy' when cold, but usually improve when fully warmed up. Also worth asking your dealer to check is there's any software updates for the car.

 

[StevieB69]

Hi Gordon, the car never goes out of comfort mode though I must admit I haven't experimented with the S setting, I'll give it a go and see if it changes anything.