E90 M3 DCT Issues

[Phat55]

Hi Guys
Okay i need some help.

My Mrs had abit of a mishap with my car whereby she drove over something which hit a hole in the transmission sump(DCT) which then caused damage to the transmission.

I had the transmission replaced with one from a salvaged M3 with about 20k miles on it.

I collected the car a few hours ago and immediately i noticed i couldn't manually downshift into 1st gear when coming to a stop.Then i noticed i couldn't manually upshift from 1st to 2nd gear.As soon as the car gets to about 3k rpm it would change to 2nd gear on its own even if its in manual mode? Arrived at my house which is about 10miles for the workshop and the car idled for about 2min as i opened up my garage.Got into the car,put it into reverse and as soon as i touched the gas pedal the car went into neutral.Then put the car into D1 and exactly the same happened?

Anyone know what this could be or does it sound like a faulty trans?

I also have my steering rack replaced and now the ABS and DSC warnings are on?Is that because the wheel alignment needs to be done then the error codes can just be cleared or is there something else wrong?

Im at my wits end with this car at the moment.One more thing the battery seems to be stuffed aswell,can that contribute to any of the above?

[BrewRifle]

I'd go back to the shop that installed that salvaged transmission to be honest. That doesn't sound right at all.

[deansbimmer]

Originally Posted by BrewRifle

I'd go back to the shop that installed that salvaged transmission to be honest. That doesn't sound right at all.

Agreed. The only thing I could suggest would be to clear the DCT's adaptations and it *might* behave normally, but honestly your issues sound more involved. Shop shouldn't have given you the car back like that.

The new rack will need to be aligned and the steering angle sensor reset with BMW software. Shop should have done that before giving you back the car.

Battery failure isn't a likely culprit there if the battery is strong enough to start the car. You'll need to pull the codes stored in the car's various modules to get an idea as to whether low voltage could be causing problems.

[azndrunk74]

Originally Posted by Phat55

I collected the car a few hours ago and immediately i noticed i couldn't manually downshift into 1st gear when coming to a stop.Then i noticed i couldn't manually upshift from 1st to 2nd gear.As soon as the car gets to about 3k rpm it would change to 2nd gear on its own even if its in manual mode?

This part I have an answer for - since your steering angle sensor hasn't been reset, you are getting the ABS and DSC errors. This also causes your transmission to automatically upshift in 1st gear around 3k even in manual mode (I assume to avoid traction issues). I had this issue when I replaced my inner and outer tie rods. After an alignment, the steering angle sensor was happy again and the errors went away on its own. The automatic shifting at 3k also stopped.

Edit: I also need to add that the shop wasn't able to reset my steering angle sensor after an alignment, the errors went away after around rougly 10 miles of driving. I'm unsure of what tool they used to try to reset it.

Get that resolved first and then see how things go with the transmission.

[Patrón]

Originally Posted by DrFerry

Possibly a faulty DCT-ECU, due to junk yard exposure. DCT-ECU might need to be reflashed.

that is my opinion as well, the electronics on the side of the transmission are faulty or the harness is damaged.

a couple of posts above mentioned the steering angle sensor also affecting the system which makes total sense as well. the garage did not do a thorough test drive.

i'd also kill the wife.

[Phat55]

Thanx for the help guys,atleast with regards to the DSC AND ABS lights i have one less thing to scratch my head over. Hopefully i get the chance to do the wheel alignment tomorrow.I 1st need to go and get a battery as the car now doesn't want to start at all.The battery is so flat nothing happens when you push the key in.

Coming back to the DCT-ECU having to be reflashed or adaptations being cleared.On the drive home which is 10 miles mostly of which is on the highway the transmission was shifting perfectly.Nice,crisp quick up and downshifts but as soon as the car stood after that it just went haywire?

Luckily for the wife i have a project car that's been keeping me busy otherwise she would've been very close to dead

[juld0zer]

Take it to a dealer or someone with ISTA/D.
Get them to recalibrate the transmission. There is a bunch of calibrations that need to be done when replacing the mechatronics, clutches, etc.
It will teach in the kiss point for both the clutches and calibrate the shift valves.
Also get them to check the transmission oil level, which may take an overnight stay as the procedure has a narrow temperature range.

Correct, the DCT will shift very harshly, be unresponsive at times to manual input and reluctant to upshift if there are DSC faults relating to road speed and possibly steering angle.

[Phat55]

Thanx Guys!

Going to get the wheel alignment done tomorrow and Alex is going to load DCT software so I'll see how things turn out once that's done.