Shifting up problems 722.9 7g tronic plus

[M156]

How many miles/km does your car have?
I had a high mileage W164 and the torque converter was bad causing the transmission to shift strangely.
You can also check the VGS speed sensor values, sometimes they go bad and the TCU doesn't know when to shift gears.

 

[User]

How many miles/km does your car have?

The mileage is now about 147,500 km.

 

[crash_doctor]

Sounds too simple, but does anyone check the volume (quality) of oil in the gearbox? To me, this sounds like a problem with the hydraulic shift mechanism in the transmission. I am far away from engine, DPF, soot, ECU...

 

[Bari87]

Do you have any fault codes stored? When was the oil last changed and the oil level checked? If they are OK, then the "general" fault is on the VGS board on the 7G. But there are addresses of workshops where they can be repaired without recoding (otherwise the car will not start).

 

[User]

Hello everyone! I was too lazy to write. I think the upshift now works as before.

I replaced the DPF and the car ran better for a while but then the same problems started. Next I replaced the back pressure sensor. This also helped, but from time to time there were still problems when shifting into higher gears. After a few months something very strange happened. The gearbox switched from 6 to 1, there was no traction, I had to try to pull over to the side of the road. The "Car Scanner" mobile app showed a DP sensor error, but there was no such error when checking with Xentry. This happened a few times before Xentry would report that the DPF was faulty or the DP sensor signal was unreliable or something like that. After replacing the DP sensor and boost sensor, everything now works as it should.

I have the latest software update from the MB dealer (which was already installed when the problems started) and the DPF now regenerates about every 200km or so depending on whether you do mostly city or highway driving. And it seems/feels like when the time for regeneration approaches, the upward movement does not happen as quickly. I'm not sure, but maybe this update also changed the exchange programs. Attached a photo of a faulty DPF and a new one. The cells of the old one have shifted upwards by 2-3 mm (the wall was broken).

 

[User]

I forgot to mention that I bought a new clean air tube after replacing the DPF and after that everything worked (almost). The next step was to replace all the pressure sensors one by one.

It's hard to say what the root cause of the upshifting issues was. I think some of the root causes were oily air mass sensors in a clean air line and a differential pressure sensor that hadn't shown any symptoms before.

Was the MAF sensor contaminated with oil caused by a faulty DPF or a leaky crankcase breather, or did one fault lead to the other?