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  1. #1
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    6HP21 erratic shifting behavior

    Hi,
    I have a AT 335i '07 and my transmission has been acting up lately. The issues are usually prolonged settling 2-3 upshift which results in slight whip like (backlash) behavior under low acceleration in D and DS modes. Under heavier acceleration the effects are masked by the transmission holding in gear longer. This is far better felt when the car is cold, as transition from 2 to 3 feels like jolt at low acceleration, but I can feel it well when fully warmed, as well (especially in DS). I am not experiencing slipping from what I can tell but the shifting is definitely not right either.
    I had the same problem couple months ago which got somewhat cured when I did fluid change, but now it's back. I am thinking it is the mechatronic, but hopefully I can get couple opinions and/or suggestions before I pull it out and rebuild it. I am looking at the Sonnax ZIP kit and replacing solenoids potentially.
    Also, if it is the mechatronic I see Revmax sells rebuilt valvebodies and 335i is listed under the application. Strange enough the transmission they list is 6HP19 and as far as I am aware 335i got 6HP21 (second generation 6HP21).

    For the record - I have 86k on the clock and the car has not been abused (casual spirited driving but no tracking).

    Any help is appreciated.

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    I have an issue when I'm in m mode and shift from 2-3 inbetween 2.5-3.5k rpm's. Obviously I'm only at part throttle, but it shifts pretty hard and jerks the whole car. It's done it as long as I've had the car, ~40k miles. Car just clicked over 80k. Im guessing its just a weird load cell that could use some tweaking. But I woudnt mind if it could shift that hard/fast at redline or 6200 Rpms since I'm still on stock turbos. Doesn't do it in D or DS. I have the alpina flash too, but Its done it before I had the flash.

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    Mine will randomly shift early when i'm on heavy throttle(manual mode). Also I get major whiplash when downshifting to first to stop..
    08 328i, totaled by women driver
    07 335i, lots of mods.
    Now- 14 Focus ST
    Click here to enlarge

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    ..and I thought I am unique... Click here to enlarge

    Joke aside...

    Also I get major whiplash when downshifting to first to stop..
    The whiplash shifting down to 1 happens to me, as well, but only if I am braking right post down shift not leaving the car to cruise down to stop. It feels just like the 2-3 upshift - if I give it more time to settle in gear I don't get the behavior at all. My car didn't have any of these issues up until 50k miles or so...

    I have an issue when I'm in m mode and shift from 2-3 inbetween 2.5-3.5k rpm's
    This is pretty much the same thing I got except I get it in D and DS. I can get it in M , as well, if I shift at the range you mentioned with light to medium throttle. My car is '07 pre 03 production so no Alpina flash for me...Click here to enlarge Sometimes I wonder if I should just replace the entire mechatronic but these things are 1500 USD. I think someone on this forum got one on the cheap from a wrecked car, but apparently I don't have his luck - I've been calling places but nothing so far. My fear is that I'll rebuild the valvebody and things will be the same...

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    Did you reset TCU adaptations via INPA or similar after doing the fluid change?

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    Did you reset TCU adaptations via INPA or similar after doing the fluid change?
    I reset and followed the re-adaptation procedure for 6HP19:

    • 4 to 6 slow pulls from full stop up to 4th gear and cruse down to stop with brakes applied at the end in D to adapt clutch packs for lower gears as well as TC
    • Driving and holding at 5th gear between 2000 and 2600 rpm for about 2.5 miles then go to 6th, cruse a bit and cruse down to stop without braking until the very end.


    I never had the transmission in safe mode while doing adaptation or post adaptation which would supposedly mean I did it right (or so I read).

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    Just to be clear, what software did you use to reset EGS/TCU adaptations? Just making sure you did not just do the gas pedal thing, that does nothing.

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    I used INPA. I've done it also with the BT tool.

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    OK good.

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    One other point everything thing I've read indicates it takes a lot longer to re adapt after this sort of reset than the procedure you outlined above. More like 50-100 miles of driving. I reset mine recently (already had Alpina flash) and it took a bit it to settle down. Just drove around mildly with progressively more throttle for the first 50 miles or so, then a few harder runs. Seems fine now, quite a bit smoother overall than before.

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    I know what you mean. The procedure I mentioned is only initial. The transmission actually took quite a bit longer to smooth out. I have to admit that I've been driving like a granny for couple hundred miles now and I hardly use DS lately. I started using DS a lot more the past two days, but I read somewhere a while ago that adaptation is done in D only. I am not sure this is true... I am also about to change my socks this up coming Friday as mine are shoot already which I am not sure if it can have any additional negative effect.

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    Which version of the EGS are you on ?

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    Which version of the EGS are you on ?
    Are you asking about the transmission firmware version or something else? Is it something I can check with INPA?

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