[iqraceworks]

So I had a very weird thing happen to me today as I'm driving my car around (07' 335i with ZF 6AT)...it kind of scared the crap out of me.

I was out driving on some backroads, and I decided to do a pretty hard pull just to make sure everything was in good working order. I'm running the MHD 2+ flash with the xHP Stage 3 transmission flash. The car/trans has 100K on it.

I was on the gas pretty hard, about 3/4 throttle....after I hit around 90mph I let off the gas to slow down. As soon as I did that, I got the "TCU Fault GEAR" on the dash display, and then the transmission decided to downshift down to D3 for some reason. Well, at 80-ish MPH, that's almost 8,000rpms!

I hit the brakes and slowed down as fast as I could.....and the transmission just stayed in D3 and wouldn't shift. I'm glad a rod didn't come out the side of the block or something. I pulled over, shut the car off, restarted it..and all was good. I got on the gas hard to make sure everything was ok, and it seemed to be.

I just recently put new fluid, filter, D-seal, and sleeve seals in the transmission...I haven't had any issues at all, it's been working great.

Why in the hell would the transmission drop down into 3rd and try to pop the engine!! ??

These are the TCU fault codes I got when I scanned the car after I got home.

4F850 - Gear Ration Monitoring Clutch E
4EE81 - Turbine Speed Sensor
50DD2 - Activation of two same priority emergency functions

Any ZF transmission experts on here that can give me some info?? Good thing I wasn't going much faster...who knows what would have happened......I sure don't trust going fast in this car at this point.

Could it have anything to do with the shift solenoids?

[iqraceworks]

Originally Posted by neilj35

When you say sleeve seals are you meaning the mechatronics connector sleeve/ seal or the 4 mechatronics rubber tube seals?

When you refilled the trans, did you fill it first without the engine running, then start the engine, run it through the gears and top the trans up again?

The gear ratio fault usually means low pressure to the clutch pack causing it slip, or afaulty clutch pack.

I replaced the D seal and the 4 sleeve seals. I filled the transmission fluid with the engine running....using INPA to monitor the transmission temps to make sure it was where it was supposed to be. I did it around. Month ago... haven't had any issues until today.

[type-dRew]

What?

3rd gear runs to 95mph at redline 7000 rpms.

Not saying you don't have an issue, clearly you do. But a downshift to 3rd at 80 isn't even a remote issue. That's like 5900rpm

[iqraceworks]

Originally Posted by type-dRew

What?

3rd gear runs to 95mph at redline 7000 rpms.

Not saying you don't have an issue, clearly you do. But a downshift to 3rd at 80 isn't even a remote issue. That's like 5900rpm

The display said D3.....but apparently it was in 2nd gear maybe ??

Whatever gear it dropped down to....the tach shot way up into the red, probably 7500 if not more.

[ptpending]

what is overall mileage of the car ?

[iqraceworks]

Originally Posted by ptpending

what is overall mileage of the car ?

100k

[ptpending]

Originally Posted by iqraceworks

100k

i see that you already made topic on n54tech.com
i think you can find more opinions on tuned n54 with at on n54tech

from my own experience with 2.0d and without tuning i had around 280000 kms mileage when sometime on freeway i had to speedup a lttle and my RPM went high few times without any visible drag
i decided that torque converter cannot lockup anymore under high load
after that i've replaced torque converter and fluid

if you dig any AT forum you can find that
Gear Ration Monitoring Clutch E error is first sign of the worn AT. You can read AT adaptations parameters from ZF TCU using INPA or Rheingold and put them here
if any clutch lock parameter will be more than 300ms then you AT is worn

[iqraceworks]

As far as I can tell.... my transmission isn't slipping. I've ran it through the gears several times.....never felt it slipping, or got any errors. I pulled the adaptations and the highest chargetime is 33ms.....so I guess that's a good sign.

I'm just trying to figure out why it just downshifted and tried to pop the motor. When the transmission goes into limp mode (gear sign on dash).....is it supposed to do that? What if you were racing on the track at 100+ mph and it did that? Seems like a great way to throw a rod out of the block.

I'm wondering if if could be a problem with the shift solenoids? Or is that normal for it do downshift like that when it goes into limp mode...no matter how fast you are going?

Is there a forum just for these ZF transmissions?

[iqraceworks]

Originally Posted by ptpending

i see that you already made topic on n54tech.com
i think you can find more opinions on tuned n54 with at on n54tech

from my own experience with 2.0d and without tuning i had around 280000 kms mileage when sometime on freeway i had to speedup a lttle and my RPM went high few times without any visible drag
i decided that torque converter cannot lockup anymore under high load
after that i've replaced torque converter and fluid

if you dig any AT forum you can find that
Gear Ration Monitoring Clutch E error is first sign of the worn AT. You can read AT adaptations parameters from ZF TCU using INPA or Rheingold and put them here
if any clutch lock parameter will be more than 300ms then you AT is worn

Actually, I've gotten more feedback here than I have from N54tech. I get the sense that most people just take their car to the shop when the transmission starts acting up...apparently, nobody knows anything about troubleshooting issues with them.......bummer.

Here are my adaptation values and fault codes if anyone has any ideas.....

[banglenot]

Attached are a couple of ZF manuals. Includes data on clutch timing, pressures, testing solenoids.

[iqraceworks]

Thanks!! I did get a reply back from the ZF tech guys. They told me that when the 6HP21 transmission goes into limp mode....it should drop into 4th gear and stay there. He doesn't know why mine dropped down into 3rd.

He said check the transmission fluid level.......not sure why it would be any different than it was a month ago when I put fresh fluid in it, but I will check it again.

He also said that the adaptation values looked good ...so he didn't think there were any issues with the clutches or seals....so that's good. He said it could be an issue with the TCU....so that sucks. I wish these damn things weren't so complicated.

I guess I will check the fluid level, and go from there.

[mainbearing]

No expert here, just enough to realize my GM transmission really is crap. Wished for a ZF.

I doubt the pre-charge pressures and times mean a whole lot. When I reset the silky smooth 6HP19 in our Audi and tried a few adaptation drives, the pressures where pretty much mid-range of -200 to 200, as far as I could remember. Did not remember anything out of the ordinary with the pre-charge times either. Middling was all I could remember.

Based on the document's shift matrix, it is interesting that your error code included Clutch E problem, as gears 4, 5, and 6 all use E. And E clutch is known to have problems as a bushing leaks ATF pressure by the oil pump.

https://axleaddict.com/auto-repair/Z...E-Clutch-Fault

Also interesting is when you restart the problem would go away. Does that say an ECU/solenoid problem? After all, the ECU is supposed to protect the engine and not allow such a shift/rpm combination.

I recently changed the "double-D"/"Bridge seal", mechatronic sleeve and the 4 round tube seals on the Audi. All were in good visible shape except the sleeve had some leaks. Afterwards the 200K mile transmission shifted beautifully. Like new really like when we got it.

With the ZF transmissions I think if people actively change the filter and fluid every 50K it will work wonders for the life of the transmission.

What fluid did you use? Maybe change out the filter/pan too (if you did not last time)? You have the plastic pan right?

[iqraceworks]

Just for troubleshooting purposes....I took the car back out today after it was nice and warned up. I ran it through all the gears manually....at wide open throttle, shifting pretty early (around 4,000rpms) just to put a lot of torque on 4th, 5th, and 6th gear. For the life of me, I couldn't get the transmission to act up at all. No slipping, no faults, nothing but good shifting.

As this point, I'm having a hard time believing that it's an "E" Clutch issue (especially with the adaptation pressures being so low).

I searched for a long time online, but I can't find much info on that 4EE81 Turbine Speed Sensor fault. Since I'm not getting a "Gear ratio" or any type of "slipping" type fault.......is there a chance that the Turbine Sensor itself could be crapping out?

Anyone have any more specifics on the 4EE81 Turbine Speed Sensor fault code?? Does that mean that the turbine speed is out of specifications, or does that just mean that the sensor is bad/faulty/giving a weird reading? I've heard of crap getting on the sensor, causing issues.

I still need to double check the transmission fluid...but at this point, I doubt that has anything to do with it.

[ptpending]

if you not have this error code active now, then you do not have problem now

[fastboatster]

Have a look at this: https://axleaddict.com/auto-repair/Z...E-Clutch-Fault
Might be an issue with clutch E, it is used for all the gears past the 3rd

[iqraceworks]

I have already changed the fluid, filter, and the seals... But every once in a while it will still do the same thing. I think my next step is to pull the valve body off again and put all new shift solenoids in it and see if that fixes the problem. If that doesn't work, I've got another transmission that I might try to rebuild myself.

I really wish the car had a 6MT and not this goofy computer controller ZF 6 speed auto.

[fastboatster]

Honestly, I don’t think that solenoids will fix it, most likely the E clutch issue. It does make sense since your car is tuned.

[Aceway]

Manual swap it

[iqraceworks]

Originally Posted by fastboatster

Honestly, I don’t think that solenoids will fix it, most likely the E clutch issue. It does make sense since your car is tuned.

It even gave me some fits before I did any power adders. If the solenoids don't fit it....I'm going to rebuild the other transmission I have....and swap it for the one that's currently in the car.

My car was bone stock when I got it...with about 80,000 miles on it. I thought these ZF 6 speeds were supposed to be bullet proof?

[fastboatster]

Well, by the most part. I've read somewhere that zf 6 speed on the lci e90 is slightly more robust, especially in terms of that e clutch.
Opening up and replacing worn stuff in a used but correctly functioning zf 6 speed might not be too bad of an idea. Might cost you some more money but might give you some extra assurance and possibly some good youtube material. Afaik, zf 6 speed is not that bad to open up and rebuild. I'd suggest taking a look at 4l60e trans rebuild videos, many of those explain the fundamentals such as how to set clutch pack clearances without expensive special tool or how to disassemble clutch drums with spring cages etc