Peugeot 407 2.0HDi Automatic Gearbox AM6 (TF-80SC) Extreme slip in D

[FarokJanos]

Hello!

Recently I have noticed that my car does not accelerate like it should in D but when i switch to M it goes like it should, so i hooked up DiagBox and did some measurements on the gearbox, the results are in the attachments.

1. D only -> It slips like hell the torque converter almost never locks up.
2. M only -> The torque converter is locking up and the car drives like a dream.
3. D <-> M Combined -> When I am going in M for example in 5th gear and the torque converter is locked up and I put the gear lever to D the engine roars up and the RPM jumps up by 300-400 but the acceleration is extremely sluggish.

My 407 has 2.0HDi RHR with 280k on the clock and it had periodical ATF changes.

What could be the issue here?

Thanks for any advice and help.

[mickthemaverick]

The first thing to do would be a diagbox global scan to see if there are any fault codes stored which may point you in the right direction.

[FarokJanos]

thank you for the answer but, there are no faults present in the gearbox ecu, neither engine related faults.

[Paul-R]

After your periodical oil changes do you tell the system that it has new oil?

And when you say periodical, do you mean you just replace the oil that comes out and then do the same again several tens of thousands of kilometres later? Or do you replace the oil that drains out, run the car for a few days to mix the oil up, drain it again and replace again and then do it a third time a few days later?

Also you say ATF. Are you using this in a generic sense or do you actually use ATF fluid? I'm concerned you might be using the wrong oil.

[FarokJanos]

i used mobil jws 3309 since its a euro4 model (2007), and i did the oil change like you described, changed, used it for a while and then changed it again the last time i did this 3 times, did everything according to the procedure so i can be sure the oil level is correct.
yes, i always reset the oil wear counter to 0 in pack repair menu in diagbox etc... i cant remember the whole path to it.

[Gibbo2286]

I suppose the first thing to check is that the oil is properly up to level, low oil level even slightly can cause slippage.

[Paul-R]

i used mobil jws 3309 since its a euro4 model (2007), and i did the oil change like you described, changed, used it for a while and then changed it again the last time i did this 3 times, did everything according to the procedure so i can be sure the oil level is correct.
yes, i always reset the oil wear counter to 0 in pack repair menu in diagbox etc... i cant remember the whole path to it.

I can't see anything untoward in that at all.

[FarokJanos]

I suppose the first thing to check is that the oil is properly up to level, low oil level even slightly can cause slippage.

I will check it today or tomorrow but i am 99,99% sure the atf is at correct level because i did everything according to the official procedures.

This whole situation is so strange and absurd, in D it is so bad but in M and SPORT its perfect and works like it should. Can the valve body be the fault? The line pressure might be lower in D than M and even in SPORT mode it manages to lock the torque converter like in M when commanded to and theese two modes need more line pressure to operate. I also heard that theese first gen tf80sc s had valve body weakness issues after some use and my car being at 280 000 kilometers it would make some sense according to me.