7g tronic problem
- Thread starter Aivis
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I have tbe same issue on my 2013 W204.
The theory is that the TCU is programmed so that gear shift happens at higher rev when the engine is cold, in order to warm up the engine sooner and reduce emissions (cold engines pollute more).
But then again this is is not a new principle (i.e. all automatic transmissions do that) and yet none of my other cars shift with a jolt when cold.
I have updated the TCU software but this did not help. The car is booked for an ATF change so we'll see if that improves things.
Said that... your 2012 car was supposed to have the ATF changed last year (it's due every 5 years), so if your ATF was changed yesterday and the transmission still shifts with a jolt when cold then I guess the ATF change does not help either - it seems it's just poor design then.....
The theory is that the TCU is programmed so that gear shift happens at higher rev when the engine is cold, in order to warm up the engine sooner and reduce emissions (cold engines pollute more).
But then again this is is not a new principle (i.e. all automatic transmissions do that) and yet none of my other cars shift with a jolt when cold.
I have updated the TCU software but this did not help. The car is booked for an ATF change so we'll see if that improves things.
Said that... your 2012 car was supposed to have the ATF changed last year (it's due every 5 years), so if your ATF was changed yesterday and the transmission still shifts with a jolt when cold then I guess the ATF change does not help either - it seems it's just poor design then.....
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It is a characteristic of this gearbox. I had the ATF changed and although changes are smoother when up to operating temperature it can still be harsh changing to 2nd and especially 1st gear when cold.
It must be related to fluid viscosity because if the outside air temperature is above 15 degrees C it is significantly smoother from start up.
A gearbox adaption may be carried out with Star but it is not guaranteed to improve things.
The general concensus seems to be that if the gearbox changes smoothly when warm then it is normal behaviour for harsh changes when cold.
It must be related to fluid viscosity because if the outside air temperature is above 15 degrees C it is significantly smoother from start up.
A gearbox adaption may be carried out with Star but it is not guaranteed to improve things.
The general concensus seems to be that if the gearbox changes smoothly when warm then it is normal behaviour for harsh changes when cold.
Petrol Pete
Hardcore MB Enthusiast
My 133339 mile 722 5g gearbox is the same, worse when in 'S' as it then uses first gear but mine is usually in 'C' on start up and will pull away in second gear (as will yours).
The gearbox and engine are not cold for long when driving so I can't see it as an issue unless you are getting a really big 'clonk' on shifting just ignore it.
The gearbox and engine are not cold for long when driving so I can't see it as an issue unless you are getting a really big 'clonk' on shifting just ignore it.
Gazwould
MB Enthusiast
Gearbox remapping ?
