DCT shift lag/delay - OEM GTS tune

[M5fanaticc]

Hey folks. Having a weird problem with my DCT. Sooo my car has the OEM GTS flash, however I’m noticing a super weird shifting issue. Most commonly, if I’m in 4th/5th/6th and shifting up, roughly between 30-50% throttle, I’ll go for the next gear, and the cluster will show I’m in the next gear, however I will feel a full second delay before it awkwardly ‘bumps’ into the next gear. My DCT fluid has been changed recently as well. Any ideas? Should I try removing the gts tune?

[spammysammich]

Was the fluid properly topped off during the change, including the top off once the fluid is warmed?

[M5fanaticc]

Originally Posted by spammysammich

Was the fluid properly topped off during the change, including the top off once the fluid is warmed?

This, I’m not sure about. How would one go about checking?

[spammysammich]

Go to the DIY section of this forum and look at the DCT fluid change. There is a special procedure you need to do. Quick answer; Get the car up on level jack stands or a lift. Pull the fill plug, if no fluid comes out, you’re low on fluid.

[spammysammich]

If fluid does come out, replace the plug, start the car in neutral or park, run it for 1 minute at 2000 rpm and then let it idle. Then pull the fill plug again and check. If nothing comes out. You’re low.

[spammysammich]

There is a thermostat that needs to open at a specific temp to allow you to add extra fluid. Who did your service?

[M5fanaticc]

Originally Posted by spammysammich

If fluid does come out, replace the plug, start the car in neutral or park, run it for 1 minute at 2000 rpm and then let it idle. Then pull the fill plug again and check. If nothing comes out. You’re low.

Thanks man!

[Adrian g.]

You aren’t running the Epic tune by chance?

[M5fanaticc]

Originally Posted by Adrian g.

You aren’t running the Epic tune by chance?

I am not, no. It is the OEM flash.

[Redd]

Try a dct reset

[carlosmachin]

Hello, did you know what it was? could you solve it?

[M5fanaticc]

Originally Posted by carlosmachin

Hello, did you know what it was? could you solve it?

My DCT clutches were worn

[carlosmachin]

It is currently happening to me on my BMW M6 F06, I am on the road and when going up a hill it does an automatic downshift but it takes about 1 second and it kicks when doing the downshift, I am worried that it is my clutches

[Redd]

Originally Posted by bmwm3fanatic

My DCT clutches were worn

What was your mileage? Worn DCT clutches are a rare thing.

[M5fanaticc]

Originally Posted by Redd

What was your mileage? Worn DCT clutches are a rare thing.

170k kilometres. But the car took a beating, a lot of racing/launches on supercharged + built motor.

[carlosmachin]

Originally Posted by bmwm3fanatic

170k kilometres. But the car took a beating, a lot of racing/launches on supercharged + built motor.

Did you have the same symptoms as me?

[M3SQRD]

Originally Posted by carlosmachin

Did you have the same symptoms as me?

Does yours happen when upshifting from 4/5/6 gears at 30-50% throttle at there’s no delay in gear number change but it takes at least one second for the actual gear upshift to occur. If yes to gears and partial throttle then, yes, your symptoms are similar. Why haven’t you checked the f06. If yours only happens going up hills then it may be different from the OPs issue or it could still be the same. What’s the mileage on your car?

[Bmwdoubles_]

If your clutch’s are worn get a DCT adaption flash.

[MineralWhiteF80]

something else to consider, just for the sake of completeness here. This is a big oversimplification of the system, but I think it's important to understand how the DCT trans and trans computer are trying to operate. Im not saying you dont have another, bigger issue, but sometimes the trans doesnt fucntion exactly the way we want.

The DCT transmission is two 4-speed sub-transmissions bolted together. One transmission handles even gears, the other transmission handles the odd gears. The DCT computer is always trying to guess which gear you will be selecting next and it proactively 'primes' the other sub-transmission into either the gear higher or lower than you are currently in so that the shift speed will be faster. At light throttle, at certain RPM ranges, it's a 50/50 guess which gear will be selected next. If the DCT computer chooses incorrectly, then it has to shift into another gear first before completing the shift, and this takes more time than 'normal.' The gear number on the dash changes immediately when the shift paddle is pulled, but the transmission takes a little longer to physically change gears before completing the shift.

For example: You are in 5th gear at 30% throttle just cruising. The DCT computer thinks you will be downshifting to 4th gear based on its sensor inputs, so it proactively shifts the other sub-transmission to 4th gear. However, you decide to upshift to 6th gear, so now the even gear sub-transmission has to shift out of 4th gear and move to the 6th gear position before the shift can be completed, which takes more time than expectation.

You can also test this in certain scenarios. For example, if you are hard on the brake in manual mode like on a race track, the transmission is expecting you to downshift to the next lowest gear. If you are hard on the brake and shift UP a gear, you will notice the gear change takes a little longer than if you downshifted, because the transmission has to quickly reselect another gear first.

You can start watching at 3:08 or so and watch through the end of the video to see what is happening here.