[Chrisguilday]

Hey guys, so I have a 2011 E93 335i.

The car has 120K miles and I don’t think the trans fluid has ever been changed. I bought it at 109K.

I recently tuned the trans to XHP stage 2 and the trans is experiencing an issue only following a very specific action.

When I’m in “Manual SPORT mode” and I’m giving it 70+% throttle, if I up-shift and “LET OFF” the gas the car will shift, but then sometimes it will then downshift back to the prior gear once I let off the gas and throw a trans code requiring restarting the car. However if I keep flooring it and shifting it will be just fine, it only happens after I let off the gas.

In non-sport mode & automatic mode it doesn’t have this issue, however I feel like the shifts are becoming a little sloppy. If I put it back to stock it still shifts a bit sloppy, but doesn’t have that downshifting problem.

So anyway, here’s my real question: I scheduled to get the fluid changed, and then I was given advice from someone else online to also replace the valve sleeves via this kit https://www.fcpeuro.com/products/bmw...t3#description

So I called the mechanic and asked him if he could do it and he said I don’t need to do that, flushing the trans is all it would need and said the fluid is like “magic” and will take care of all of that. I’m not sure if there’s some merit to what he’s telling me or if he thinks I’m just dumb (I’m pretty mechanically inclined but I have no knowledge on transmissions)

The mechanic is the highest rated bmw / Mercedes’ shop in my area. Their name is Prostar Mercedes & BMW service.

So is he right? Will I be fine with just a fluid flush? It’s $400 for labor & fluid.

Thanks!

[smatanovic]

Originally Posted by Chrisguilday

Hey guys, so I have a 2011 E93 335i.

The car has 120K miles and I don’t think the trans fluid has ever been changed. I bought it at 109K.

I recently tuned the trans to XHP stage 2 and the trans is experiencing an issue only following a very specific action.

When I’m in “Manual SPORT mode” and I’m giving it 70+% throttle, if I up-shift and “LET OFF” the gas the car will shift, but then sometimes it will then downshift back to the prior gear once I let off the gas and throw a trans code requiring restarting the car. However if I keep flooring it and shifting it will be just fine, it only happens after I let off the gas.

In non-sport mode & automatic mode it doesn’t have this issue, however I feel like the shifts are becoming a little sloppy. If I put it back to stock it still shifts a bit sloppy, but doesn’t have that downshifting problem.

So anyway, here’s my real question: I scheduled to get the fluid changed, and then I was given advice from someone else online to also replace the valve sleeves via this kit https://www.fcpeuro.com/products/bmw...t3#description

So I called the mechanic and asked him if he could do it and he said I don’t need to do that, flushing the trans is all it would need and said the fluid is like “magic” and will take care of all of that. I’m not sure if there’s some merit to what he’s telling me or if he thinks I’m just dumb (I’m pretty mechanically inclined but I have no knowledge on transmissions)

The mechanic is the highest rated bmw / Mercedes’ shop in my area. Their name is Prostar Mercedes & BMW service.

So is he right? Will I be fine with just a fluid flush? It’s $400 for labor & fluid.

Thanks!

I assume you have the ZF 6hp, and not the GM transmission. At 120k I would suggest the transmission service kit which replaces all of the seals between the valve body and the transmission. While you are in there, it is worth while replacing the mechatronic solenoids, especially if you plan to keep the car for the long haul.

I went through all of this recently, and the transmission now shifts like new.