ZF 6HP26X - high adaptation values

[X5only]

Originally Posted by wpoll

Well sheet...

Thanks X5only - your screenshot blows my current theory out the windows.. :-)

Clearly, there is some very mixed terminology being used in ISTA and the values shown don't mean what I think!

Oh dear...

Wait ... sorry, I forgot I did reset the adaptation before starting work on the trans. I read somewhere that a reset should be done before servicing the mechatronic and not after .

[haigha]

Great read... in case it's of any help, here are the values from my Foxwell before I reset the adaptions:

[wpoll]

Thanks again, RRPhil - that all makes perfect sense.

It also aligns with some further thoughts I've had (probably as you wrote your response!) - I am now thinking that I'm wrong in thinking the "high" valvue shown in ISTA are a problem - I think they simply show an old, worn transmission.



And here's my thinking...

The ISTA values shown above are on a screen labelled "existing adaptation values" but are then listed as "clutch fill pressures". To me, these clutch fill pressure now appear to be actual stored pressure values (in mbar) and not an offset from some nominal value. If so, they are NOT way high - they are all about what you would expect to see in an older transmission.

ZF state the adaptation limits thus: -



These are negative and positive mbar and ms offsets, applied to some nominal base value. I don't think these correlate directly to the values shown in ISTA as I had initially assumed. For one, ISTA is NEVER going to show a negative pressure value!!

This is clearly shown in this screen grab from one of Mickey Figueroa's great YouTube videos, where the -30mbar offset is shown as being applied to a nominal 600mbar pressure value, giving a stored pressure value of 570mbar.



So what I had assumed were out-of-spec adaptation offset values are in fact likely to be stored pressure values, after the adaptation offset has been applied. I'll dig deep into ISTA and see if I can locate the actual stored offset values but I didn't spot them on the first (or second!) look.

In light of this, I no longer think my adaptations are out-of-spec. Not knowing what the nominal pressure values are for each clutch but assuming that 600mbar might be typical, I think my offsets are still well within the limits stated by ZF. They also align with what both RRPhil and Mickey Figueroa indicate, that worn transmissions usually exhibit positive adaption offset values.

So now to figure out what the issue actually is!

*edit* Hang on!! - I missed that clutch D is showing a value of 200mbar - that's -400mbar below the nominal 600mbar value - so that may be worth looking into!

[Happy]

Originally Posted by RRPhil

the fact that the adaption/adaptation values are high for all the clutches may just be an indication that the transmission has done a high mileage and is generally just ‘worn’.

Phil

+1

Originally Posted by wpoll

I am now thinking that I'm wrong in thinking the "high" valvue shown in ISTA are a problem - I think they simply show an old, worn transmission.

+1

I am currently working on facilitating the rebuild for mine as we type. The above quotes are 99.9% the issue.


E53 RiPPeR
XOuTPoST jUNkiE
ReVELaTiON 22:21

[wpoll]

So I did a little more testing today. While I don't have the data reading/logging tools that show solenoid currents, activation states etc., I can view items like engine RPM, TC turbine speed and transmission output speed, so I started there.

I ran several 1st-6th gear runs on a long, flat empty road and got only one instance of the 5th ger jerk, and a very minor one at that. The one jerk was when I was using just enough throttle to accelerate through the gears and no more. When I accelerated hard, the transmission shifted very well, with clean changes and no slipping.

Here's what the live data looks like in 5th gear, at about 70km/h (right where I've previously felt the jerks): -



1440/1664 = 0.865 - close enough to the 5th gear ratio of 0.867, so no significant slipping there... but I did feel the one slight jerk just after it changed to 5th, moments before this screen shot. The jerk is hard to spot on the screen recorded live data, as the screen and data update speeds are somewhat limited.

And after I packed up the laptop, cables etc. and headed home, traversing a short section of motorway, I discovered when the issue really shows up. On a slightly downhill section of 80km/h highway, I got a couple of decent jerks as soon as the transmission selected 5th gear at about 70kmh, under very little to no throttle.

So under load, at engine speeds above about 1,800rpm, it's fine. At lower rpm, with very light loading, it can jerk in 5th only (but doesn't always). And usually only a couple of quick instances.

I'm going to VERY carefully re-check the fluid level, just to eliminate that variable.

And... no codes and it's never been in trans fail-safe mode.

More testing to come.

[wpoll]

Update - just completed a 1,000km road trip. Had one instance of the 5th gear jerk (about 30km into the trip) and after that, it shifted and worked fine (meaning no worse than usual!). Got 7.0l/100km (33.6 US mpg) and car ran great - if you don't count losing yet another LF DHC!

[haigha]

Good to hear, Wayne! I hope it continues to improve.

Sorry about the DHC... whatever that is! I don't think I've had to deal with that problem yet.

[wpoll]

Originally Posted by haigha

Good to hear, Wayne! I hope it continues to improve.

Sorry about the DHC... whatever that is! I don't think I've had to deal with that problem yet.

DHC = Door Handle Carrier, and if you've owned an e53 for more than 5 minutes, you'll have changed at least one. Probably more.

[haigha]

Originally Posted by wpoll

DHC = Door Handle Carrier, and if you've owned an e53 for more than 5 minutes, you'll have changed at least one. Probably more.

21+ years and zero so far... shouldn't jinx myself

[X5only]

Originally Posted by haigha

21+ years and zero so far... shouldn't jinx myself

Mine started breaking about 8 years ago when the X5 got booted out the garage. Issues started during winter. The two window regulators also broke. But now I know the easy fix for DHC instead of replacing with new, if it breaks for the third time .