6AT jumping out of gear strange codes

Blackarrow335i

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Nov 5, 2016
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Simpsonville, South Carolina
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BMW 2009 e92 335i N54 ST
Edit: just took the car for a spin nothing crazy no wot or anything, logged my voltage on KL15 with protool and noticed that I get Voltage fluctuations! While driving/idling it goes as low as 12.4V
So Voltage fluctuation from 12.4-13.8V car

Edit: checked voltage with multimeter (battery, under the hood terminals and alternator) all 14.4v at idle with all accessories on. Car off 12.6V

Edit: while checking the voltage at idle I gave it a little throttle (tiny bit) kept it there but rpms kept climbing to almost 5k (video is attached)

Edit: still have the feeling this might be Voltage related, not 100% sure if that’s true or not but that’s my gut feeling. I Unplugged the IBS sensor at the battery completely so it’s literally just a ground cable at this point,
Still not seeing 14V not with MHD and not in the hidden Menu 13.8-13.2 is where I’m at no matter what!
Came home from work pulled codes and got bunch of them picture is attached I wasn’t able to regenerate those codes also first time all those codes popped up since all this is going


Hello everyone, can someone help me out please?
2009 e92 N54 AT 6266 ST stock at with xhp s3
Since quite a while I have a strange issues going on.
A few month back (April or May) I installed my ST everything worked out well car ran fine on 14psi WG pressure then we started tuning
Got to about 19 psi and suddenly my transmission won’t stay in Gear/Mode example: DTC off M3 then wot and as soon load increases it will jump into either D6/S6 or D5/S5 usually nothing else happens also don’t get any codes (not in MHD and also no codes with xhp) and can just shift as nothing happened and keep on driving. But sometimes (same example as above) and transmission goes into safe/limp mode and stuck in 3rd til I turn the car off and on and everything works fine! That’s when I get codes please see picture!
I thought well time to rebuild my transmission so I did with PD clutches and bushings and a rebuild valve body I mean rebuild not just a sonnax zip kit!!! Installed the transmission did the relearn process etc. everything seemed to be fine and we kept on going now we are at 21psi but the one day same shit happens again car won’t stay in gear/mode! Then next day car drives and pulls fine for weeks and suddenly same shit again! It’s coming and going!
What I did so far! Changed our entire engine and transmission harness but not injector harness, replaced ground strap,replaced battery checked mechatronic sleeve connector to make sure it’s not leaking and plug sits flush 3mm from housing to plug as the ZF manual states, and as I said earlier it’s pretty much a brand new transmission! Sometimes it works fine then this shit happens and the next minute it pulls fine again! Please help I’m lost at this point!

TIA

Link to video if what It looks like


 

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Last edited:

matreyia

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Apr 19, 2017
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And the old transmission has the exact same issue! With many many more miles and abuse miles on it that’s why I thought it’s time for a rebuild but 2 weeks in and this shit started again with the fresh rebuild transmission! Not saying it couldn’t be messed up but less likely at this mom I would think!

OK, if the old unit did the same thing, then it is an electronic sensor issue or wiring somewhere. It's not a hardware issue. If you replaced all wiring, then it will be your TCU or DME. That's all that's left to be checked.
 
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Blackarrow335i

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Nov 5, 2016
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BMW 2009 e92 335i N54 ST
Well 2 weeks without rules out dme. Do you have any custom coding or vo changes? So the only things that werent changed were harness and electronics. I would clear those codes and try to see if moving shifter or using a paddle or potholes trigger so can try get an idea what triggers. It's actually really good that protocol found code. My next step would also be email zf those codes. Or those Australian guys that did the dct and 6hp28 swaps as they may have ran into those codes and would know what module it's from.
transmission harness is changed! Do you have a name or anything from the guys who did the swap?
 

Rob09msport

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On further digging old forum posts show that those are tool32 codes no longer used anymore so to get info you need to access with inpa but the cd codes in past references the szm unit which is I the shifter and has to do with the shifter sending the gear to trans and display
 
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Rob09msport

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Also I believe if shifter disconnects while driving the trans defaults to 3rd gear so I really think it's your shifter cause im sure if too many ecc bytes flag on can bus it just ignores and treats like a disconnect
 
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Blackarrow335i

Specialist
Nov 5, 2016
86
59
0
Simpsonville, South Carolina
Ride
BMW 2009 e92 335i N54 ST
On further digging old forum posts show that those are tool32 codes no longer used anymore so to get info you need to access with inpa but the cd codes in past references the szm unit which is I the shifter and has to do with the shifter sending the gear to trans and display
This sir is really useful information thank you ! One code says display transmission data!
 

Blackarrow335i

Specialist
Nov 5, 2016
86
59
0
Simpsonville, South Carolina
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BMW 2009 e92 335i N54 ST
OK, if the old unit did the same thing, then it is an electronic sensor issue or wiring somewhere. It's not a hardware issue. If you replaced all wiring, then it will be your TCU or DME. That's all that's left to be checked.
I’ll try to change dme tonight (I have a matching cas dme and key) just tried to avoid paying $100 for a new MHD license only for testing! But guess there is no way around!
 

Rob09msport

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So on pm we have came to a guess that voltage drop may be issue he has random drops to mid 12s on logs we saw and he is an late build 09 notoriously picky with voltage. Bentley manual states 12.3 to 12.6 off and 13.5 to 14.5 running and at idle full load like every single possible thing heated seats,defrosters,etc 12.6 and then at 2000 rpm back Into spec. Anyone have any insight ?
 

Rob09msport

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Btw my agm is 3 yrs old now and I am 11.7 after sitting for day or 2 but I also have been flashing like a mofo. This thread made me realize I think I need another goddam battery. I have a h8 agm platinum from advanced auto think 105 ah i just know i got one that is highest spec I could find anyone have any good suggestions for both of us.
 
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Blackarrow335i

Specialist
Nov 5, 2016
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Simpsonville, South Carolina
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BMW 2009 e92 335i N54 ST
I'm not even going to read back,

Did you check for broken wiring in the shifter?




My trans didn't hold up long enough to prove this was my problem, but I'm confident it was.
Yes I had a wire snap on me 2 years back but it’s different issue now I still double checked that but nope!
 

iminhell1

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Jun 17, 2018
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Yes I had a wire snap on me 2 years back but it’s different issue now I still double checked that but nope!


How did you repair it?
Solder can break, if it's not a clear heat shrink you have to cut it off to see what's going on.

I had real similar situation as you. I thought I solved it 3 times and every time it'd come back.
I first though it was tune related, tried different OTS tunes, same result, though took varying times for problem to arise.
Replaced battery. Was fine for a while. Mind you I'm adjusting tunes all the time here.
Comes back. Found an error in part of the base tune I was using. Corrected it and car felt much better.
I added a trans cooler because last track outing I let it get warm enough to the slip point, about 250*F. It went into failsafe.
Since I added the cooler it just hasn't worked the same.


From what ISTA says, trans temps have to get to and above, don't quote me because I don't have it right in front of me, 180*F for learning to take place. I haven't got that high since I put the cooler in. And TBH I think that's what killed my trans ... no word on what or how yet.


So I'm kinda thinking that while you went through the steps for the trans relearn, they weren't done to the letter. As far as I can guess that trans temp is a very big deal and needs to be spot on.

I also think that there is an issue with the user adjustments through xhp and that a conflict lies between that software and mhd.




And what my trans did the first time there was a problem was default to 3rd gear, I was doing 120. How the F does and auto moneyshift?
 

Rob09msport

Major
Oct 28, 2017
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Monroe CT
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09 335i msport le mans 18 x5
How did you repair it?
Solder can break, if it's not a clear heat shrink you have to cut it off to see what's going on.

I had real similar situation as you. I thought I solved it 3 times and every time it'd come back.
I first though it was tune related, tried different OTS tunes, same result, though took varying times for problem to arise.
Replaced battery. Was fine for a while. Mind you I'm adjusting tunes all the time here.
Comes back. Found an error in part of the base tune I was using. Corrected it and car felt much better.
I added a trans cooler because last track outing I let it get warm enough to the slip point, about 250*F. It went into failsafe.
Since I added the cooler it just hasn't worked the same.


From what ISTA says, trans temps have to get to and above, don't quote me because I don't have it right in front of me, 180*F for learning to take place. I haven't got that high since I put the cooler in. And TBH I think that's what killed my trans ... no word on what or how yet.


So I'm kinda thinking that while you went through the steps for the trans relearn, they weren't done to the letter. As far as I can guess that trans temp is a very big deal and needs to be spot on.

I also think that there is an issue with the user adjustments through xhp and that a conflict lies between that software and mhd.




And what my trans did the first time there was a problem was default to 3rd gear, I was doing 120. How the F does and auto moneyshift?
Default to 3rd is cause its disabling the e clutch which works in conjunction with other clutches for 4th 5th and 6th. It is the simplest gear to engage that is what the trans defaults to. The temp with learning is def an issue I think for alot of us I wonder if should use a 180 degree tstat instead of the 160.