I have a 2001 A4 1.8T AWM,about 5 or 6 months ago,the car started to jerk when trying to shift into 4th gear.
I changed the Transmission control module once,being my mechanic at the time,claimed it was bad after trying to communicate with it via his scan tool with no success.
The car would not drive very fast at all,before i changed the TCM,it was very slow to pick up speed on my way to my mechanic,so he told me it was shot and i needed another one.
I don't know why it died,the position of the TCM is under the passenger side floor,which suffered from no water leakage that is the normal cause for a TCM to fail.
Anywho..so i found a replacement on ebay for 195.00 which worked after he installed it,no issues from then on.
About 3 month later,the jerking started,when trying to shift into 4th gear in my Automatic tiptronic 2001 A4 1.8T.
When i put the gear in drive,it shifts fine in 1st,2nd,3rd but when trying to shift to 4th,the car gives a slight jerk and the transmission kicks back down to 3rd gear,i can see the gear shift back down on the screen.
when the TCM tries to tell the tranny to go to 4th gear,it attemps to go into the gear but for some reason it can't so it goes in to limp mode somtimes,at which i would see the screen with all the gears light up,then i can't even drive the car,the rpms just reves up and i won't move forward,so at this point i would have to pull over to the side of the road and turn off the car and back on again to reset the car's ecu computer,then i can drive it fine.
At other times,it won't go into limp mode,it'll just kick back down to 3rd and i'll be able to keep driving,it just depends on what she feels like doing at any given time or perhaps it depends on how fast i am going?
So to avoid all this bull spit,i drive her in tiptronic mode,i tip the shift up 3 times and don't even bother with 4th gear,when slowing down in 3rd gear,the tranny kicks down normally as it should,from 3 to 2 and 1 at a complete stop.
I took her to the dealership where i bought her not even a year ago,feb 2010 is when i bought her,they are working with me though. The guy told me to bring it in and i did today and dropped it off,saturday they are going to have the same mechanic that i had change the TCM months ago look at it,he is a russian guy that knows a shit load about Audi's and works on them all the time and i am not worried about him trying to rip me off,he helped me out a few times.
One of the owners of the dealership was driving me back to my other car a1997 vw jetta and was telling me,he doesn't think its a tranny issue but a electrical issue but he said don't quote him on it,he isn't a mechanic but he said if it was a tranny issue,he knows a guy that will rebuild it for 1500.00!! aswsome price! he said the guy rebuild 2 cars for him and they work to this day,so i'm all set if need be.
So the hardest part of all this trying to diagnose what actually wrong with her,once i find out,i'll take care of her,i made a promise to my baby that i would'nt let her stay cripple.
transmissions are pretty complicated things.
drop one under an Audi and it gets even more complicated. I'm inclined to agree with the dealership owner that told you it sounds like an "electrical issue".
let us know how it turns out
Transmission problems can have a wide range of severity and cost of repair. I prefer to repair my car on my own this allows you to save a lot of money on workshops in addition, I like it. I can also mention https://at-manuals.com/ a website where you can find more information about your box, you always need to go in and choose the make and model of the machine) This service has helped me out more than once