Dct transmission missing shifts sixth to seventh gear.

[usmcgruntz]

Bought a used 2015 bmw z4 e89 35i with the m sport package and the DCT transmission. I’ve had no issues with the car till after I put a MHD tune stage one on it. While on the highway above 60 MPH and cruising. When I drop down or am in 6th gear and quickly accelerating to 7th. The car will give me a red transmission light for 0.5 seconds and turn off. It will miss the gear and I decelerate. When I slowly speed back up to 7th it shifts just fine. It stores a 5A54 code also. This has happened 3 times and always from 6th to 7th. It doesn’t happen in sport mode. Only in comfort. Brought it to the bmw dealership and they checked the transmission fluid level and said it was fine. The transmission fluid in the car lasts for the life of the car and never needs to be changed. They reset the transmission and told me if it does it again to take off the MHD tune and check it because it can confuse the computer control module talking to each other. And if that doesn’t work. It could be a bad sensor in the car or might need the entire valve body/transmission replaced which is more than the entire car is worth. Has anyone ever had this happen before? Could it be the extra power from the tune is showing that the wear on the transmission or a compatibilty issue. Been told by MHD that the time will have nothing to do with how the transmission shifts.

[B21]

Originally Posted by usmcgruntz

Bought a used 2015 bmw z4 e89 35i with the m sport package and the DCT transmission. I’ve had no issues with the car till after I put a MHD tune stage one on it. While on the highway above 60 MPH and cruising. When I drop down or am in 6th gear and quickly accelerating to 7th. The car will give me a red transmission light for 0.5 seconds and turn off. It will miss the gear and I decelerate. When I slowly speed back up to 7th it shifts just fine. It stores a 5A54 code also. This has happened 3 times and always from 6th to 7th. It doesn’t happen in sport mode. Only in comfort. Brought it to the bmw dealership and they checked the transmission fluid level and said it was fine. The transmission fluid in the car lasts for the life of the car and never needs to be changed. They reset the transmission and told me if it does it again to take off the MHD tune and check it because it can confuse the computer control module talking to each other. And if that doesn’t work. It could be a bad sensor in the car or might need the entire valve body/transmission replaced which is more than the entire car is worth. Has anyone ever had this happen before? Could it be the extra power from the tune is showing that the wear on the transmission or a compatibilty issue. Been told by MHD that the time will have nothing to do with how the transmission shifts.

I think you've effectively already asked this question?

So point one..the fluid in the DCT should be changed every 50k-75k miles along with the two filters..Getrag who made the box stipulate that in their documentation..BMW stated no service required along with 15k-20k mile engine oil change intervals...whereas the entire industry expects 5k-10k oil change intervals..

Its relatively common for the temp gearbox sensor to fail causing various errors..

So a fluid change along with sensor is the lowest cost best bet strategy..

After that you're looking at worn clutch plates caused by too much agressive driving..or maybe the mechatronics..

Simple solution is remove the MHD flash and live with it..

[KennyP]

Originally Posted by usmcgruntz

....The transmission fluid in the car lasts for the life of the car and never needs to be changed.

Dont believe that! I have serviced my DCT 2 times already during 8+ years of ownership. its usually recommended to change oil, filters every 50k miles or so... even less if you track it regularly. Service also includes new plastic oil pan with gasket.

Both times when i had it serviced it was mostly because that pan gasket was leaking. First time i noticed some slippage during hard acceleration and that made me look under the car. I guess enough oil had leaked out and that caused it. Had it serviced and all was fine again...
Second service was recently... again because noticed a leak while on a lift. Didnt notice any performance issues though. Still had it serviced and leak fixed.

[usmcgruntz]

The dealership told me that that the fluid should never be changed and it’s “lifetime.” And I agree I’ve read online that it should be changed but they told me that the next step is replace if the entire thing or the entire valve body. Sounds like I should just tell them to replace the sensor and the fluid? I think that’s about 1,500$ USD. As far as I know it’s never been changed. Also is this something I can order the parts and do myself with limited amount of special tools or better left to the dealership.

[B21]

Originally Posted by usmcgruntz

The dealership told me that that the fluid should never be changed and it’s “lifetime.” And I agree I’ve read online that it should be changed but they told me that the next step is replace if the entire thing or the entire valve body. Sounds like I should just tell them to replace the sensor and the fluid? I think that’s about 1,500$ USD. As far as I know it’s never been changed. Also is this something I can order the parts and do myself with limited amount of special tools or better left to the dealership.

The dealer is following the factory line...Its tricky when you're not technical and/or do not have access to the necessary tools / equipment..

I'd call their bluff..de-install MHD and live with it till it starts to fault without MHD..

Unless you have access to factory manuals and various tools its not the easiest thing to tackle..

The problem is most of us long time owners know is that its often v tricky to diagnose an issue without detailed investigation and often parts substitution..

In that context I'd suggest a MHD de-install..

If it was me I'd get a decent Indy that really knows Getrag boxes to look at it..

By now this box is retired so the skill base in main dealers is denuded!

[usmcgruntz]

Ordered parts to change the oil pan gasket and the transmission filter and fluid also changed back to stock. Seems like the extra power from the tune is actually putting to much stress on the transmission that isn’t brand new. Thank you so much for the info! I can’t tell you how much it helped!

[KennyP]

There are 2 filters in the transmission. Make sure you got both. Also last service my indy transmission specialist shop said that they would not service it with just a replacement pan gasket and that new pan is a must. First service they did put old pan back with new gasket, but back then they did not have much experience with this transmission..my car was actually first one with this transmission they touched... now years later they had accumulated more experience with that DCT and know better. Theres one m3 with same transmission in my town that they have worked on extensively... syncro work and so on...

[usmcgruntz]

I bought the 800$ one with the 2 filter kit off fcp euro with the liquid Molly fluid. Looks like quite the challenge. I have seen videos online about the transmission fluid change and how to but not the oil pan specifically for the Z4 e89. Any links would be helpful since you have to drop the subframe for it.

[B21]

Originally Posted by usmcgruntz

I bought the 800$ one with the 2 filter kit off fcp euro with the liquid Molly fluid. Looks like quite the challenge. I have seen videos online about the transmission fluid change and how to but not the oil pan specifically for the Z4 e89. Any links would be helpful since you have to drop the subframe for it.

There is no requirement to touch any subframes for a gearbox filter /sump oil change.

Any BMW DCT oil /filter change write up applies equally to E89s..

The key issue / difference to most gearbox oil,changes is the requirement to add additional fluid after initial top up whilst engine is running and the appropriate gearbox temp….usually another 1.5 litres ish goes in..

This leads me to the suspicion that your bmw dealer did not correctly check the fluid in the first place …

[usmcgruntz]

The subframe is for the oil pan that is now leaking after the tune also that wasn’t when I bought it. And it seems like they did not check the actual fluid level. The tech kept saying that Bmw does not let them do anything with transmissions at all. I’ll post again when I have it drained

[B21]

Originally Posted by usmcgruntz

The subframe is for the oil pan that is now leaking after the tune also that wasn’t when I bought it. And it seems like they did not check the actual fluid level. The tech kept saying that Bmw does not let them do anything with transmissions at all. I’ll post again when I have it drained

At the risk of sounding like a stuck record I fail to see technically any correlation between a leaking sump and MHD..

The DCT is unusual as it’s the only bmw gearbox that has to be checked hot with the engine running after a pre software induced program set..

Sounds like you have a pup / bad dealer support

[usmcgruntz]

I think the tune has caused the problems that would have happened naturally. Happened sooner rather than later. And yes. The dealership basically charged me 700$ to tell me I had fluid and it was up to levels but couldn’t do more unless I needed the entire valve body changed and or the transmission. Also they reset the codes in the transmission. Also right after I put the tune on coil pack on cyl 2 went bad. Replaced them all and haven’t had a problem since.

[B21]

Originally Posted by usmcgruntz

I think the tune has caused the problems that would have happened naturally. Happened sooner rather than later. And yes. The dealership basically charged me 700$ to tell me I had fluid and it was up to levels but couldn’t do more unless I needed the entire valve body changed and or the transmission. Also they reset the codes in the transmission. Also right after I put the tune on coil pack on cyl 2 went bad. Replaced them all and haven’t had a problem since.

Very common for coils and /or plugs to fail when tuned …

My bet is a fresh oil n filter change on the DCT and the problem may go away..it’s a classic low oil level behaviour..of course you did say that they had checked it..but without doing the proper procedure they would never know and it’s impossible with any diagnostic to ascertain the level..