722.6 lock up behaviour?
Thread Starter
Junior Member
Joined: Jul 2016
Posts: 23
Likes: 0
S211 320cdi
722.6 lock up behaviour?
What is the usual behaviour of the lock up on a 722.6 box? Iv just fitted a second hand box, it's lovely and smooth and changes fine but Iv noticed a dramatic loss in MPG and it seems to be slipping more than the old box, the old box was worn with usual symptoms of juddering.
Iv reset gearbox adaptions but I'd like to see someone else's adaptions as I think the ecu isn't accepting them very well, I'm wondering whether to put the TCU in virgin state, but don't want to brick it and leave me stranded.
Iv reset gearbox adaptions but I'd like to see someone else's adaptions as I think the ecu isn't accepting them very well, I'm wondering whether to put the TCU in virgin state, but don't want to brick it and leave me stranded.
Thread Starter
Junior Member
Joined: Jul 2016
Posts: 23
Likes: 0
S211 320cdi
Why would virginizing the TCU be dumb? As far as I can tell it's the same as a proper hard reset of the unit, considering I've fitted a completely different box to what the TCU has picked it's adaptions from then I was wondering whether a hard reset will re adapt the torque converter lock up.
What it's got to do with the thread title is, Iv not long purchased the car, and I've only ever driven the car with a worn box and TC, Iv fitted this new to me box and TC and it behaves well but I instantly saw a drop in mpg, one thing Iv noticed is I'm sure I used to get lock up in 5th gear whilst cruising on the motorway, I'm wondering whether this constant slipping of the TC is causing the loss of mpg, I did stick das on and log TC data and it was constantly set to "SLIPPING" and I never seen it move over to "locked" I didn't sit on the motorway and log what it was doing though, as Iv never driven a s211 with a good condition box before I was asking for help on whether its normal behaviour.
I can be cruising at 70-80-90mph and it won't lock off fully, from 70+mph Iv noticed on light throttle I get about a 200rpm slip as I accelerate, where as before I clearly remember sitting at 2,000rpm at 70mph and now it'll be at 2,200rpm untill I let off and it'll then hold at 2,000rpm.
Thread Starter
Junior Member
Joined: Jul 2016
Posts: 23
Likes: 0
S211 320cdi
Well yes maybe my terminology is a bit loose, das has the option to reset the unit after replacement and to load unit with factory settings.
So from what Iv described does it sound like normal behaviour? I have no error codes on TCU, and isn't there an error code for gearbox slippage? So shouldn't it be picked up? I can strip the valve body out the old box along with conductor plate as it'll be a free fix as the other box behaved well apart from the shudder.
The box and TC Iv fitted was a £150 gamble, it was untested, so If I get it running right it's a bonus.
So from what Iv described does it sound like normal behaviour? I have no error codes on TCU, and isn't there an error code for gearbox slippage? So shouldn't it be picked up? I can strip the valve body out the old box along with conductor plate as it'll be a free fix as the other box behaved well apart from the shudder.
The box and TC Iv fitted was a £150 gamble, it was untested, so If I get it running right it's a bonus.
Thread Starter
Junior Member
Joined: Jul 2016
Posts: 23
Likes: 0
S211 320cdi
Slipping is when the lock up clutch doesn't fully engage and it slips, hence the name, lock up is when the lock up clutch in the torque converter locks up, hence the name.
Here's a picture on the behaviour of a 722.6 transmission torque converter so you can understand better
Source of graph
https://mbworld.org/forums/c-class-w...-question.html
P0811 is your fault code for excessive clutch slippage, here is where I referenced it from
https://mbworld.org/forums/c-class-w...t-first-2.html
It seems I also have patience....
I just bolted the crap to the car and hoped for the best
I was running out of time and it was raining, in an ideal world I would of rebuilt it, but other projects and time made it not ideal, but hey, shoot me down for going against the grain.
Here's a picture on the behaviour of a 722.6 transmission torque converter so you can understand better
Source of graph
https://mbworld.org/forums/c-class-w...-question.html
P0811 is your fault code for excessive clutch slippage, here is where I referenced it from
https://mbworld.org/forums/c-class-w...t-first-2.html
It seems I also have patience....
I just bolted the crap to the car and hoped for the best
I was running out of time and it was raining, in an ideal world I would of rebuilt it, but other projects and time made it not ideal, but hey, shoot me down for going against the grain.
MBWorld Fanatic!
Joined: Jan 2009
Posts: 9,225
Likes: 1,798
From: V E G A S
1922 Ford Model T / no OBD
Contact member handle MAVA on other forum. He rebuilds those transmissions and is consider forum expert on the task.
Talking to forum clown is not likely going to help you.
Talking to forum clown is not likely going to help you.
Thread Starter
Junior Member
Joined: Jul 2016
Posts: 23
Likes: 0
S211 320cdi
And I did wonder what was up with the forum clown, didn't do so well to be honest he needs a change in profession
