125i Auto Trans performance Problems/tunes

[NE_P8riots]

I’ve owned my 125i 2011 for a great deal of time, loved it but I just can’t get over how poor the shifting is in “steptronic” (in my defence, lol, i couldn’t buy a manual trans as they were rare and my partner cant drive a manual) I drive up mountain roads, and am in second gear around a tight corner yet can’t downshift to first (unless i am under 2500rpm) this is painful as in second the lower end is painfully slow to reach 7000rpm to third. now I cant get any where near to “money shifting” as it rarely succeeds 3-4000 on the down shift, it’s terrible! The “gm” auto box is painfully slow to shift, feels like a granny shift each time. Any simple or easy fixes? I’m looking to tune the engine from a 125 to a 130 yet i feel like its pointless as the transmission is just rubbish. ruins the driving experience 😞

[///Makis]

Originally Posted by NE_P8riots

I've owned my 125i 2011 for a great deal of time, loved it but I just can't get over how poor the shifting is in "steptronic" (in my defence, lol, i couldn't buy a manual trans as they were rare and my partner cant drive a manual) I drive up mountain roads, and am in second gear around a tight corner yet can't downshift to first (unless i am under 2500rpm) this is painful as in second the lower end is painfully slow to reach 7000rpm to third. now I cant get any where near to "money shifting" as it rarely succeeds 3-4000 on the down shift, it's terrible! The "gm" auto box is painfully slow to shift, feels like a granny shift each time. Any simple or easy fixes? I'm looking to tune the engine from a 125 to a 130 yet i feel like its pointless as the transmission is just rubbish. ruins the driving experience 😞

I think there was a tune for the auto trans from BPC

You have the GM 6L45 transmission right?

You should be able to find the thread in the 3 series e90 forum. I think Hassmachine had made the tune for the trans and I believe it's still available but you need to make a project at BPC for a 3 series or something like that not an e82.

I'm not sure how much this will help you but a few others posted they liked how the tranny shifted and responded post tune, so it could be worth looking into.


Edit:

I meant bimmerlabs, not sure if it's the same as BPC

[E92William]

The bimmerlabs tune is basically from a x3 3.0si and yeah it makes a really big difference, lot more direct and faster torque converter lock up and quicker shifting. If it did in a 328xi imagine in an utterly detuned 125i.

[carscatscoffee15]

Originally Posted by ///Makis

I think there was a tune for the auto trans from BPC

You have the GM 6L45 transmission right?

You should be able to find the thread in the 3 series e90 forum. I think Hassmachine had made the tune for the trans and I believe it's still available but you need to make a project at BPC for a 3 series or something like that not an e82.

I'm not sure how much this will help you but a few others posted they liked how the tranny shifted and responded post tune, so it could be worth looking into.


Edit:

I meant bimmerlabs, not sure if it's the same as BPC

BPC is a shop in Raleigh, NC.. the guy who worked on the N52s there left and opened up his own shop also in Raleigh. Stage Fabrication and Performance. Great guys who are true enthusiasts and do great work.

Bimmerlabs is totally different

[carscatscoffee15]

Originally Posted by NE_P8riots

I've owned my 125i 2011 for a great deal of time, loved it but I just can't get over how poor the shifting is in "steptronic" (in my defence, lol, i couldn't buy a manual trans as they were rare and my partner cant drive a manual) I drive up mountain roads, and am in second gear around a tight corner yet can't downshift to first (unless i am under 2500rpm) this is painful as in second the lower end is painfully slow to reach 7000rpm to third. now I cant get any where near to "money shifting" as it rarely succeeds 3-4000 on the down shift, it's terrible! The "gm" auto box is painfully slow to shift, feels like a granny shift each time. Any simple or easy fixes? I'm looking to tune the engine from a 125 to a 130 yet i feel like its pointless as the transmission is just rubbish. ruins the driving experience

when I got my e82 3 years ago I was in the same boat as you luckily it didn't stay stock for long.. depending on your goals with the vehicle there are a few things you can definitely do to make it feel a bit more lively.

I started by having it stock for a month, then going with Active Autowerke's OFS tune for the N52. I coupled it with their headers as well as their exhaust. Forewarning, this makes the car louder. As for the tune, idk what it could have been but I did get a couple of torque codes and had the car go limp on the interstate once.. In addition, the car felt a bit more responsive but still had some sluggishness especially in the 2-4th gears.

After debating on switching tunes and waiting a while (probably too long but to my benefit) I plunged and took the drive down to StageFP as BPC told me they no longer supported the N52 platform. They did my 3 stage intake manifold, MILVs (look this up on the forums there's a wealth of information and definitely helped the car a lot especially on the top end), and changed a couple of gaskets that might as well have been changed while they were in there.

Car felt amazing the whole drive back to NYC. I feel like the car woke up and actually did give a couple of 30i's a run for their money. Heck even people in cars quicker than mine couldn't believe that my little AT NA motor could keep up/produce the sound it was outputting. It really is the driver, not so much the car.

I wanted a bit more, don't daily my car, don't mind the exhaust smell and after much deliberation finally took the plunge and removed my secondary cats. My butt dyno enjoys this and the car is now how it should have been always. Sometimes I forget I have a GM autotragic. Freeing up the exhaust has helped the car breathe better. I went with Supersprint straight pipes. I kept my resonator but I'm curious if removing it would even do anything (doubt it, will probably increase the drone)

YMMV but in a nutshell:

1. exhaust
2. headers
3. tune
4. 3SIM
5. MILVs
6. straight pipes

hope I was able to help! going through tunnels and under overpasses is my favorite thing in the world besides a nice twisty back road!

the Bimmerlabs tunes I have heard good things about so don't let that sway your decision. Kassel Performance in York, PA does quality work as well (from what I've seen and heard.. I would like for them to work on my car one day too!)