I've been noticing a slight hesitation when I'm cruising at around 35-40mph. It feels like it loses power but gains it back, repeats every few seconds. It's subtle and it's not like it's slamming or anything. I know there's a huge thread on bimmerfest regarding this, and it seems like it's a really common problem. I can live with it if it doesn't do any harm. It just seems more of an annoyance to me. How are you guys dealing with it?

 

This problem is usually due to a failing mechatronics unit which is a fairly expensive repair. I have read of one person who replaced the solenoids in the mechatronics unit himself and posted a DIY on it. The cost was very reasonable and didn't seem to hard to do for the average diyer.

If you have a warranty on your car, then get it checked out and hope that your warranty company covers the repair. I haven't had that problem crop up on me yet and I'm at 80k but if I do I'll be bringing it to my local indy BMW specialist to get it repaired through my warranty company. I have an exclusionary warranty plan that will cover this repair if and when it's needed.

One way to deal with it is if you are traveling at that speed and the hesitation bothers you then just put it in sport mode. It raises the RPMs and causes that problem not to happen at that speed.

Good luck!

JP

 

read this thread - 05 545i Transmission Surging Issues help! - Bimmerfest - BMW Forums

I had the same issue with the 30-40 slipping, hunting back and forth when lightly gassing it.

My quick fix - replace the trans pan/filter, ZF fluid, replace mechatronics sleeve, and reset the adaptation. So far that has remedy my transmission issues, and was cheaper than replacing parts. The car shifts very smoothly now.

 

thanks for the response, boost. so replacing the sleeve helps? I thought it just seals the mechatronic unit? if the problem is within the mechatronic itself, won't the problem still be there?

in any case, that sounds a lot cheaper than replacing the unit itself. how much did that job cost you?

 

The mechatronic sleeve on mine was leaking that's why I had it replace. plus that part is only 16 bucks, fairly cheap item consider everything else cost an arm and leg for our car.

The shop only charged me an hour of labor since they were already working on my car trying to fix all the leaks.

 

Replace the solenoids for the 1-2 gear along with the sleave (as stated it's only $20 - and fails very easily)

I'm going through the same thing right now on my 550i . I hope I can get away with the solenoid service, but I'm having some problems finding out of the solenoids I see online will fit into my 2010 550. I might have to end up buying a whole new mechatronic.

Here's a GREAT PDf that explains (in pretty precise detail) how the ZFS transmission works, and how it differs from a standard (manual) and convential automatic:
http://www.bmwmotorsports.org/BMW_docs/transfund1.pdf

I'm a big tech nerd, so this was a good read for me. I think for most, it's too complex. But it might be useful for someone like me who doesnt know which components to spend money on, short of replacing the whole mechatronic. Also, be aware that the mechatronic unit is just a glorified valve body, with some electric (and solenoid) parts that make it modern.

 

ron - try contacting these guys for the solenoids - The CTSC - ZF Parts

 

thats where I've been looking, but Im kind of confused.

According to everything I have looked at, I have a "GA6HP-26Z" trans in my 2010 e60 550i

All the stuff for the 6HP-26 on their site doesn't have the 'Z' at the end. I can't find the 'GA6HP-26Z' part, anywhere on their site.

So I'm curious, maybe you know, if these, are what I need:
Solenoid Kit - 6H19/26/32 M-shift

I emailed them yesterday, but have yet to hear back. Maybe you can shed some light for me (and possibly others?)

 

If the transmission pan isn't leaking, can I just reuse the old one? Car has only 68k miles. After researching more, I plan to at least get the mechatronic sleeve replaced with a fluid change.

Local indy quoted $280 for sleeve replacement (no fluid change), and $765 for new pan/filter, sleeve, and fluid.

 

Mis-read your post. With the pan included, that's about right. But you don't need a new pan as much as the seal. Unless the pan is cracked, or they damage it upon removal, I'd say save the money.

Sleeve and refill should be 400-600 . It's about 1hr w/o fluid change, 2 hrs with.

You can re-use the old pan, but it might be a good idea to buy a new seal since it's cheap. The most common "oh crap" on this work, is damaging the pan or the sleeve when removing the old one...

I saw on ebay earlier, they sell a kit with the seal and sleeve. It was $55