DCT transmission issue SOLVED!

[BGut12]

my DCT has been acting really weird.

issue #1: as shown in the video, the car is in S3 sport+. it has a 1-1.5 second lag when downshifting. i’ve noticed it so far going from 5-4 and 4-3. you can hear me click the paddle, the car immediately switches to 3 on the dash, but sounds like the car goes into neutral and then finally downshifts. right after that i downshift into 2 and it’s perfect. it’s very weird also because it doesn’t always do this, it’s just random and does it whenever it wants.

issue #2: i noticed the other day, had the car in M1 mode where i have D2 and Sport setting on and the car shifted normally through 1-5 but didn’t want to go past that into 6 itself.. i was merging onto the highway so pressed the gas a bit more but not enough for it to do it’s normal delay before it shifts up because i know how that feels. it just literally cruised on 5 for 5 minutes before it went by itself into 6.

overall everything feels weird with this DCT, it’s just not enjoyable at all to drive right now. i switched from an F80 and it was amazing in that car. could this just be as simple as resetting adaptations at BMW, putting on an XHP flash, or is it something more serious? if anyone has any info please let me know 🙏🏼

https://youtube.com/shorts/CoVD21r9C...sIUvD1W6oUp2Zv

[Chrgnthru]

I'm also experiencing your second issue. Only mine is on 3rd gear and it doesn't happen all the time. It only does it at WOT and shifts ok while normally driving on M mode.

[BGut12]

Originally Posted by Chrgnthru

I'm also experiencing your second issue. Only mine is on 3rd gear and it doesn't happen all the time. It only does it at WOT and shifts ok while normally driving on M mode.

yea i only noticed it that one time. like i said just overall acting really weird right now. i’m going to try XHP if that doesn’t work i’ll be taking it to BMW to get it diagnosed

[M5Rick]

I'd say reset adaptations and go easy on the drive for a bit.

[BGut12]

Originally Posted by M5Rick

I'd say reset adaptations and go easy on the drive for a bit.

yea i’m going to do that when i get a chance. i did a stage 2 XHP flash last week and had a couple occasions to drive it and it’s still doing it, but way less. only way to really prevent it is to stay above 2k rpms, but still happens sometimes, or keep foot on the gas while downshifting.

[BGut12]

guys, i literally can’t believe it but the problem is gone. the DAMN TIRE SIZES were wrong and because of this the transmission was acting up!! i still can’t believe it, like how can that even be a thing programmed in BMWs computers?

to me this issue was not a small one, i thought the clutches were toast or i was going to have to find a new transmission to put in. i was on the verge of selling the car.. it’s insane to me how something so stupid and small causes the transmission to act like it’s on its way out. i couldn’t enjoy this car since i bought it until now, it was the furthest i thing from enjoyable to drive. if anything is happening with your car, make sure your tire sizes are correct before doing anything else!

[code7rpd]

What tire sizes were you running?

[BGut12]

Originally Posted by code7rpd

What tire sizes were you running?

off the top of my head im pretty sure the fronts were 265/30/20 and rear 295/30/20

now i put on 285/35/20 and 315/30/20 R888Rs and the problem is gone.

[M5Rick]

^ These nearly are the correct sizes for the car apart from that it should be 265/35/20 for the fronts with the factory 20'' rims.
Maybe those previous tires were quite worn near the minimum limit and of course with those new Toyo's you have got phenomenal grip now which have the correct 35 front/30 rear mix.

[BGut12]

Originally Posted by M5Rick

^ These nearly are the correct sizes for the car apart from that it should be 265/35/20 for the fronts with the factory 20'' rims.
Maybe those previous tires were quite worn near the minimum limit and of course with those new Toyo's you have got phenomenal grip now which have the correct 35 front/30 rear mix.

yea it looked off to me from the beginning in the front, looked too thin. that’s just how i bought the car so i didn’t think much of it. thank god i decided to switch tires because i would’ve never found the problem. as far as tire life, no they were pretty new not worn at all.