Quote:
Originally Posted by kiwis.4.8i
Hi Wayne , travis here from down in invercargill.
What's this transmission reset you speak of..??
Is it the one where you turn the key on, press down the accelerator for 30 sec..??
Or is it something else..??...I occasionally have a hard shift between 1st and 2nd.
Cheers
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Hey Travis,
OK - firstly, the "press the accelerator down for 30secs" thing is an urban myth - it does nothing, or at best forces the transmission into one of the more aggressive shift patterns, which tend to mask the 2-1 slam. This makes you think it did something - but it really didn't.
The control module (EGS) on the ZF 6HP26X transmission can "learn" to shift cleanly as the transmission ages and wears. This process is called "adaptation".
These adaptations can be cleared from the EGS via suitable BMW software or hardware scanners - INPA, ISTA-D, DIS, BMW-Scanner, Foxwell etc.
Clearing of these adaptations needs to be done if you perform any maint. on the transmission that will change the shift performance. And a simple fluid/filter change is not such a process - normally.
I've just changed the internal seals that connect the mechatronic body to the transmission's fluid pump and clutches etc. This will change the fluid pressures being applied to the clutches, changing the shift performance, so an adaptation clear is called for. This then allows the EGS to "learn" the new shift pressures etc.
Simply clearing the adaptations won't fix anything - the transmission will re-adjust itself back to the old behavior pretty quickly (since nothing has changed) and in fact it will likely perform poorly until it does so.
If your transmission has a 2-1 slam (and it seems they mostly do eventually) then it needs proper maint. I wish it wasn't so but there's no getting around that. That maint. might be simple or it might be more involved (and costly) so proper diagnosis is also important.
I figured $350 to replace the seals (which at 250,000km and 16 years were going to be in need of replacing) was worth it as part of my "diagnosis".
So far, it seems to have worked out well....
