2005 4.8is transmission shifting / slipping issue

[blackbeast]

Thanks for the update! I'm glad it fixed the problems you had.

Any chance you could write out a detailed list of what you replaced, and possibly links where to buy them?

I'm not having transmissions problems myself, but a transmission service is on my to do list this spring.

[blackbeast]

I was doing some searching and came upon this: Important Information About Electrostatic Discharge - Sonnax

.... just thought I would leave this here for anyone thinking about doing this work on their transmission, good info to know before digging in

[squidzilla]

Thanks for posting this. I am weighing getting another X. A 2005 4.8is and this makes me fell better about most of the tranny issues I have read about.

[Clockwork]

Thanks for all this. I'm having a troubling feeling with my tranny and after 190k kms I should replace the valve body and its solenoids and some rubbers too.

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[kvc]

Wow - totally inspired after reading this thread. The symptoms you described are almost identical to those I have been trying to diagnose/remedy since purchase of my E53 last year...
I'm in your debt for such a detailed analysis and process of elimination. I'll be looking into this further and time permitting, will attempt to address this soon. As blackbeast has already asked, could you please post links to vendors so the required parts can be ordered? TIA

[blackbeast]

Looks like this site has everything we need, thectsc.com (no affiliation)

A 7 piece solenoid kit is $470, another $200 gets you a full fluid/filter replacement kit with the real ZF fluid, so all in all not too shabby assuming the transmission feels new afterwards like the OP's

The best part is it all seems very doable at home if you're careful and take your time

[OrangeFurious]

Bumping old stuff, but this is a fantastic thread. I had almost the exact problems on my 4.4i ('05 / 181k) and occasionally get a code P17E9 on my 4.8is ('06, 88k) - will look into the solenoids for the 4.8is.

Oddly enough, what fixed my slipping and frequent failsafe modes on the 4.4 was brake rotors. Just about all my transmission issues cleared up within a week of replacing all four rotors and pads.

[amancuso]

This thread seems like it died about a year ago. My new to me 4.8is w/ 83k miles seems like it shifts too quickly on moderate throttle (speed limit of 35-45) and to make it actually go it has to downshift. It also does something weird very rarely but has done it about 10 times over the past 3k miles. When traveling at lower speed, say 40, and I try to accelerate gingerly without stomping the pedal, it feels like the transmission shifts halfway, makes a whooshing sound then bumps into gear, almost like it's sliding before actually shifting into gear. I am getting the fluid changed along with that square adaptor, 4 small hoses and the electrical plug gasket changed, also checking the transmission programming and adaptations reset this weds. I guess my next step if this doesn't work is the solenoid or even whole mechatronics unit change?

[upallnight]

Check the circumference of all the tires. Are they the same? People with the 4.6 and 4.8 like to run stagger setup with these X5. If the circumference are not the same the differential will try to even out the rotations of the wheels which isn't really great for the differential.

[amancuso]

Originally Posted by upallnight

Check the circumference of all the tires. Are they the same? People with the 4.6 and 4.8 like to run stagger setup with these X5. If the circumference are not the same the differential will try to even out the rotations of the wheels which isn't really great for the differential.

the tires are the factory correct size for the car with the same tread depths on all 4...