How does Exhaust sensor effect gearbox?

[Richard.Wilson]

I've been chasing a fault with the gearbox on my W124 230TE. The gearchanges are sharp and clunky, especially when cold. It also seems reluctant to change up until it gets hot, it seems to rev out like it was in kick-down.
I figured it may be the fluid pressures too high, and don't know how to cheak and adjust them...anyone know how?
However, a local Merc specialist says that the gearbox gets a signal from the sensor in the exhaust (mine is a late W124 with 4-speed auto and a catalytic converter). This signal is used to keep the engine revs higher, to warm up the Cat faster. If the sensor is faulty or slow to react , he says it will cause the symptoms I have.
Is this correct?
How do I check the sensor?
Can I dissable the function so the gearbox behaves itself?
I'd much prefer to have a smooth change than a hot Cat!
Thanks
Richard

 

[guydewdney]

yes- this is correct. all mbs do this

by finding the correct values and comparing them - i have had a look on my autodata cd and it doesnt tell me - sorry. ask a mb dealer?

i wouldn't



talk to george fraser west london, hes good with gearboxes.

 

[Richard.Wilson]

Thanks,
Sensor was toast and GSF say Lambda sensor is MB only, but my local autofactor had one on the shelf for £33, made by Commercial Ignition in Nuneaton Part # XLOS103.
Fitted in half an hour, couple of grazed knuckles.
Seems to work a treat, gearchanges are much improved, still a bit "solid" but I'll live with it until I can find out what the pressures are, and how to adjust them.
Anybody know how?

 

[Arnie]

Do you have the right oil in the gearbox? Dexron and the TQF oils have different additives which give the former softer and the latter harder change characteristics (to suit the design of the auto 'box).

Dexron II or III is the correct type for MB gearboxes. Try a refil if nothing else helps.

 

[Richard.Wilson]

Thanks Arnie,
I use Dextron II, and changed the filter about 12K ago, but maybe another fluid and filter change would be good.
I'll report back.
Anybody know the pressures and test procedure for these boxes?
Richard

 

[piestore]

auto box

Hi

gearbox modulating pressure and working pressure could be your problem, the modulating pressure is controled by a vacuem unit on the n/s of the box, make sure the pipe is secure and its not leaking also check it is the right one for the vehicle (they are colour coded) via MB parts if all the above are ok your dealer should only charge about an hour to check pressures and another .5 h to adjust if required