Hyper_545i

Hello All,

My 2004 545i w/steptronic (117k miles) has started to exhibit a hesitation or jerk while cruising between 35-40mph. When coasting, or during light throttle, there seems to be an intermittent hiccup, jerk that seems to happen every 3-4 seconds if I stay at that speed. If I accelerate past this point, it seems to be fine. Also if under moderate to heavy acceleration, the symptoms do not present. I started to notice this after the trans fluid was drained/filled due to a leak from the trans pan. I am not sure the indy actually reset the trans adaptation via INPA. Is this necessary? Could this be causing the issue or is this a mechatronics issue? There a tons of post all around the web surrounding this issue. I also have a slight delay when going into reverse. But not 3-4 seconds as some have described. More like 1-2 seconds, if that.

Usually replacing the mechatronics resolves this issue from what I've read. But at 4-5k this seems like overkill. When the mechatronics is replaced, so are the solenoids and the tranny adaptation is reset. Should I try the tranny adaptation reset and then solenoids?

Amherst

First thing to check is if the transmission is up to the proper fill level which is a bit tricky on these transmissions. I suspect you may have improper fluid level.

The procedure requires the vehicle in the air and level with the engine running and the fluid brought up to 40 degrees C. All these parameters must be met for proper level. I would try that first since the shifting was normal prior to the pan change and go from there.

How much do you trust the mechanic who performed the pan change? There are unscrupulous wrenches who try to cheat on the fluid due to the high cost.
If the transmission shows a proper fill level I would consider sending a sample of the fluid out for testing. They can tell you if the proper fluid has been used and certain defects of the transmission can be detected. The cost of repair of these units warrants a little detective work.

Hyper_545i

Amherst,

Thank you for the quick reply! I'm not sure how much I can actually trust this indy. He was referred to me by a friend. I ask about the level and he was sure it was correct. He used to work for BMW, so I trusted him and left it at that. He also stated he used the ZF Fluid, again, how can I be sure? Do you know if the transmission adaptation values need to be reset after the fluid change? Also, where are you located? I am in South Jersey as well.

Amherst

Well you can be sure by checking his work. I always suspect when problems arise in an area where a repair was performed. 90+% of the time the mechanic screwed up.
You can check the level yourself but it is a bit of a pain on jackstands. I just did one a couple weeks ago.Alternatively you can have another mechanic check it.
If the level is correct take a sample of the fluid and send it out for testing. There is a major testing company that can tell you everything about that fluid. I would have to do a search to find their info, I don't know it off the top of my head.
As far as the adaptations after a pan change, I have done several and these were basically maintenance changes on units not exhibiting any major problems. The adaptations were not reset and everything ran normally.

So you also hail from the great state of Southern New Jersey? I'm in Camden County near Cherry Hill.

Hyper_545i

I'm not too far away from Cherry Hill. Maybe 15-20 minutes. Do you own or work at a shop? Do any side work? Nice to see a fellow Jerseyan on the forum!

Amherst

Yes, nice to meet a local fellow enthusiast!

Was a line mechanic many years ago, left the trade but have kept up to some degree on various vehicles and maintain my own and a few others. Have always loved BMW's going way back in the day. My son's and I have visited the BMW Welt in Munich a few years back. Neat stuff there.

PM sent.

KyleB

+1, first thing to verify is that the correct fluid was used, and that it is at the correct level. If you can confirm both of those, I'd try resetting adaptations before I thought about replacing either the Mechatronic as a unit or replacing the set of solenoids and the seals between the Mechatronic and the transmission casing. Low or improper fluid will cause these gearboxes to do all sorts of funky things.

Also, if you have access to INPA I'd go see if any faults have been registered in the TCM; If you haven't gotten the dreaded iDrive message then you probably won't see any, although checking won't hurt. If you see any codes for 'gear ratio monitoring', you likely have something going on with your Mechatronic.

Good luck!

Hyper_545i

Thanks for all of the replies!

KyleB,

I got an email from Klaus of TCTSC. He said with the symptoms I described it's likely a solenoid issue with them not holding pressure. I am going to have the fluid level checked as suggested by you and Amherst. How is the level measured? Should it be at 40c when checking?

If it turns out to be fine, and the solenoids to be replaced, can this be done with the mechatronics installed? Or does the mechatronic unit need to be dropped first? Also if the solenoids are replaced, I'm assuming the tranny adaptation will need to be reset via INPA?

KyleB

Yes, Klaus is a great guy. Your V8 car has ZF's 6HP26 gearbox.

All of your questions are answered here:

https://5series.net/forums/diy-do-yo...thread-137584/

H F

Excellent write up , very informative and well done ..