Violent transmission shift: 6HP19 AT xHP Stage 3

Jeffman

Lieutenant
Jan 7, 2017
877
#1
While driving in slow traffic tonight in D mode around 15 mph (2nd or 3rd gear, don’t know) I accelerated slightly when suddenly at around 1800 rpm the transmission shifted so hard and made such a large noise (bang) that I thought I was read-ended. If I were to guess what happened, it seemed that the TCU thought I was doing a WOT pull in manual mode and shifted hard to do a 2-3 or 3-4 shift.

(Car had been driven normally from cold start for about 15 minutes until that point. No dashboard lights or iDrive screen errors. This is the first time something like that has happened since driving with xHP Stage 3 since it was released. 2008 335xi with 66,600 original miles that has never been raced or beaten on, other than numerous WOT 3rd-4th pulls for tuning).
Any ideas, comments, or suggestions as to what caused such a hard and violent shift?
 

Jeffman

Lieutenant
Jan 7, 2017
877
#3
Hows your battery?
New OEM battery 3 years ago. Temp in the 40s. Should be fine. MHD said voltage was 14V immediately afterwards. Curious if you know evidence of poor battery function leading to TCU errors?
 

SlowE93

Sergeant
Jul 2, 2017
298
#4
Mechatronics sleeve failure can lead to tcu errors. Btw, more than likely you have a zf6hp21 not the 19.
 

Jeffman

Lieutenant
Jan 7, 2017
877
#5
Mechatronics sleeve failure can lead to tcu errors. Btw, more than likely you have a zf6hp21 not the 19.
Thanks. Do you know what’s involved in replacing one or more mechatronics sleeves?

And I believe you’re correct about the transmission being a zf6hp21.
 

SlowE93

Sergeant
Jul 2, 2017
298
#6
Hope its a simple sleeve fix for you ! Easy to do . You should do pan and filter (built into the pan), fresh fluid and sleeve. If you are not afraid to take things apart, also do the sleeves between trans and valvebody while you are at it.
 

SlowE93

Sergeant
Jul 2, 2017
298
#8
Hope its a simple sleeve fix for you ! Easy to do and cheap
Okay thanks. I’ll look for a diy
I have only some pics of when I did mine. Let me know if you need them , I can text them to you.
 

Jeffman

Lieutenant
Jan 7, 2017
877
#9
Hope its a simple sleeve fix for you ! Easy to do and cheap

I have only some pics of when I did mine. Let me know if you need them , I can text them to you.
Will do. Thanks for your advice.
 

iminhell1

Specialist
Jun 17, 2018
98
#10
I have a sleeve and was going to change it the last time I did my filter, few months back. But I can't see why I'd need to unless it's leaking. From what I can tell it seals the electrical cables running from outside to inside the trans case. So if it's bad it's going to be leaking fluid. I see no leaks. I can't find it having anything to do with fluid pressure, so it should have no impact on shifting, harshness or anything the like. More likely here is pin corrosion. Unclipping the wiring breaks the corrosion and fixes a problem. The seal is a placebo?


The seal between the VB and case though, that can leak pressure and cause problems. but it requires dropping the VB to replace it.




Battery, Best I can say is I think replacing my battery fixed my trans issues. I can't say for 100% though. I changed up my tune a little around the same time. And I haven't had any track time to really stress the car to make sure it's gone. But I can say the new battery did seem to cure some ghosts the car had.
So just make sure yours is charged good; leave it on a charger for a good day (3A or less). Yes it may have voltage, but what is it under stress?
 

Jeffman

Lieutenant
Jan 7, 2017
877
#11
I have a sleeve and was going to change it the last time I did my filter, few months back. But I can't see why I'd need to unless it's leaking. From what I can tell it seals the electrical cables running from outside to inside the trans case. So if it's bad it's going to be leaking fluid. I see no leaks. I can't find it having anything to do with fluid pressure, so it should have no impact on shifting, harshness or anything the like. More likely here is pin corrosion. Unclipping the wiring breaks the corrosion and fixes a problem. The seal is a placebo?


The seal between the VB and case though, that can leak pressure and cause problems. but it requires dropping the VB to replace it.




Battery, Best I can say is I think replacing my battery fixed my trans issues. I can't say for 100% though. I changed up my tune a little around the same time. And I haven't had any track time to really stress the car to make sure it's gone. But I can say the new battery did seem to cure some ghosts the car had.
So just make sure yours is charged good; leave it on a charger for a good day (3A or less). Yes it may have voltage, but what is it under stress?
Thanks for your insight. I found this YouTube video by ShopLifeTV which also does a great job of explaining the problem as well as how to do the repair. He seems really knowledgeable about BMWs. If I lived in LA I’d want him to do the work for me.
@doublespaces Is he on this forum? If not, he should be!
 
Last edited:

iminhell1

Specialist
Jun 17, 2018
98
#12
Thanks for your insight. I found this YouTube video by ShopLifeTV which also does a great job of explaining the problem as well as how to do the repair. He seems really knowledgeable about BMWs. If I lived in LA I’d want him to do the work for me.
@doublespaces Is he on this forum? If not, he should be!


Around the 14 minute mark you can see where the sleeve actually goes.

 

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