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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Transmission issues 6AT E90 335i



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      01-04-2023, 02:25 PM   #1
Apharaohh
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Transmission issues 6AT E90 335i

Not exactly sure if this is where I should be posting but here goes.

I have been having issues with my transmission where if I put it in reverse it clunks, but any other gear its fine. At start up, the car idles a bit rough, but I have done a walnut blast, changed spark plugs, and coil packs it helped it out a lot but there is still a rough idle. When the car is cold, the transmission shifts terribly sometimes shifting up then immediately shifting back down and sending my RPMS through the roof. When taking off from a stop, I have to take off very slowly to avoid the terrible shift. Once driving for a while, the car seems to run fine with almost no issues with shifts. The car if you brake hard enough causes the car to shudder and then launch while driving (RPMS are rising but car is barely moving then RPMS drop and the car takes off)

I took it to a shop, but they mentioned that I was leaking tranny fluid. They recommended replacing fluid and seals but weren't sure if that would cause the transmission to fail since its been like this for a while they are worried about metal flakes in the oil. They said that if there was a lot of flakes, the likelihood of needing a new transmission is needed.

please let me know if I should do the fluid and seal change or start looking for a used trans
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      01-04-2023, 03:58 PM   #2
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Quote:
Originally Posted by Apharaohh View Post
Not exactly sure if this is where I should be posting but here goes.

I have been having issues with my transmission where if I put it in reverse it clunks, but any other gear its fine. At start up, the car idles a bit rough, but I have done a walnut blast, changed spark plugs, and coil packs it helped it out a lot but there is still a rough idle. When the car is cold, the transmission shifts terribly sometimes shifting up then immediately shifting back down and sending my RPMS through the roof. When taking off from a stop, I have to take off very slowly to avoid the terrible shift. Once driving for a while, the car seems to run fine with almost no issues with shifts. The car if you brake hard enough causes the car to shudder and then launch while driving (RPMS are rising but car is barely moving then RPMS drop and the car takes off)

I took it to a shop, but they mentioned that I was leaking tranny fluid. They recommended replacing fluid and seals but weren't sure if that would cause the transmission to fail since its been like this for a while they are worried about metal flakes in the oil. They said that if there was a lot of flakes, the likelihood of needing a new transmission is needed.

please let me know if I should do the fluid and seal change or start looking for a used trans

I would start with the transmission service. filter (which is the whole pan) fluid, solenoids and sleeves.

Your rough idle has nothing to do with the tranny. Most likely walnut blast or leaking injectors.
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      01-04-2023, 10:04 PM   #3
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Quote:
Originally Posted by Bimmer_Bro View Post
I would start with the transmission service. filter (which is the whole pan) fluid, solenoids and sleeves.

Your rough idle has nothing to do with the tranny. Most likely walnut blast or leaking injectors.
Rough idle can be caused by failing torque converter. In park and neutral the torque converter spins at engine speed. Device inside manipulates the ATF flow in one direction to allow engine idle or another to couple engine and transmission and propel vehicle. This device also allow engine to idle while you are in gear at full stop or just cruising without being on the accelerator by making the torque converter slip internally. So what happens if something is wrong there and internal slip of torque converter isn’t taking place? Or is taking place intermittently?
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      01-16-2023, 10:30 PM   #4
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I don't buy into the "changing high mileage fluid will ruin your trans" train of thought. I've changed the fluid in many high mileage transmissions for the first time and it's never made things worse. Usually shift quality drastically increases.

If your trans is already toast and is slipping, removing fluid that has a ton of suspended clutch material could in theory make it slip more, but that's about it.

How many miles are on the car?

I would definitely do the fluid, mechatronic sleeve, bridge adapter and tube seals. That pretty often solves poor shift complaints in these cars. Make sure you use Lifeguard 6 fluid or Mercon SP (same thing) too. Not Valvoline or LM1800, Red Line, etc.
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      01-17-2023, 09:44 AM   #5
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Like others have said...if it was me, I would start with servicing the transmission with new seals, fluid, filter pan, and NEW SHIFT SOLENOIDS. When they get old they don't modulate the fluid pressure/flow properly and cause all kinds of issues.

And don't reset the adaptations!!
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      01-17-2023, 10:43 PM   #6
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Quote:
Originally Posted by whyzee125 View Post
I don't buy into the "changing high mileage fluid will ruin your trans" train of thought. I've changed the fluid in many high mileage transmissions for the first time and it's never made things worse. Usually shift quality drastically increases.

If your trans is already toast and is slipping, removing fluid that has a ton of suspended clutch material could in theory make it slip more, but that's about it.

How many miles are on the car?

I would definitely do the fluid, mechatronic sleeve, bridge adapter and tube seals. That pretty often solves poor shift complaints in these cars. Make sure you use Lifeguard 6 fluid or Mercon SP (same thing) too. Not Valvoline or LM1800, Red Line, etc.
wouldn't the problem of it slipping more make it a bigger issue if there is suspended material in the fluid? Wouldn't I be better off getting a used transmission and changing the fluids and seals on that?
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      01-17-2023, 10:44 PM   #7
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Quote:
Originally Posted by iqraceworks View Post
Like others have said...if it was me, I would start with servicing the transmission with new seals, fluid, filter pan, and NEW SHIFT SOLENOIDS. When they get old they don't modulate the fluid pressure/flow properly and cause all kinds of issues.

And don't reset the adaptations!!
Why shouldn't I reset the adaptations? If there is low fluid in there or suspended material which could possibly cause the fluid to become thicker, wouldn't that mess with the adaptations and therefore making it shift even worse since the new fluid would be thinner?
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      01-17-2023, 11:59 PM   #8
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Quote:
Originally Posted by Apharaohh View Post
wouldn't the problem of it slipping more make it a bigger issue if there is suspended material in the fluid? Wouldn't I be better off getting a used transmission and changing the fluids and seals on that?
If your trans is already slipping, the fluid change is not what did the damage but it was already causing damage by slipping. People neglect transmissions for most of a car's life then blame the maintenance for its failure when in fact, it was the years of neglect.

I would do the service--more than likely that will solve your problems. It's very common on these when the bridge adapter or tube seals leak, to cause pressure loss. Not to mention, if your fluid is original it is severely overdue for a change and can't do its job as it's supposed to anymore. I'd say 90% chance it shifts like new afterwards.
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      01-18-2023, 06:56 AM   #9
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Quote:
Originally Posted by Apharaohh View Post
Why shouldn't I reset the adaptations? If there is low fluid in there or suspended material which could possibly cause the fluid to become thicker, wouldn't that mess with the adaptations and therefore making it shift even worse since the new fluid would be thinner?
This has been more than proven over the years with these ZF transmissions. Unless you do a full rebuild and change out internal parts like clutches, resetting the adaptations does nothing to help the transmission, and will likely make things worse.

As clutches wear, seals wear, and fluid viscosity changes....the transmission WILL adjust the adaptations on it's own. The transmission has done it's job and adjusted the adaptations over the years....why force it to start from OEM settings, which are probably going to be far from where they need to be. I've even seen posts on here where things are so far out of spec....the transmission can't adjust things back to where they need to be after
It's forced to reset everything.

And.....don't forget the fact that ZF, xHP, and every shop that specializes in building ZF transmissions will tell you the same thing......don't reset the adaptations.
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