Well sheet...:rolleyes:

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...:confused:

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 :dunno:.

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

https://i.imgur.com/keOYlV5.png

https://i.imgur.com/uB5wRR9.png

Thanks for the update, X5only...

Of course, the quickest way to be proven wrong about anything at all is to make any form of statement on the internet!

The ink is barely even dry on my last long post and I suddenly see lots of ISTA screen shots showing negative values for clutch fill pressure!! Dang it - don't recall seeing those before! Just when I thought I was getting closer to getting a handle on this mental piece of engineering!! :rofl:

OK - I'll stop think out loud on here and give you all some peace and quiet - ignore me and I'll likely go away. ;)

+1

+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

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): -

https://i.ibb.co/fYrg6Nb6/ZF-6-HP6-in-5th-gear.png

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. ;)

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! :rolleyes:

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. :rolleyes:

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