Hi,
I own a 01 2.7T auto with 76k miles on it.
3 weeks ago, check engine light on with the code 0741 for torque converter lock up, so the TC was rebuilt and ATF and filter were replaced.
Right after I pick up the car from a local German car specialist, I feel the something different with the car. When I release gas pedal, the car will jerk. Mostly happen in rpm below 2000 and sometime 2500 and not during gear shifting.

I brought the car back to the shop, they keep it for a week and couldn't find any problem. They checked engine mounts, transmission mounts, and have the company that rebuild the TC to check the transmission and TC, also found no problem. They too feel the jerk but can't explain it.

The car has tune up service and timing belt change at 70k miles.
I know a lot of things can cause this symptom, like TPS, dirty throttle body. But since the problem started to happen immediate after I pick up the car, I am hoping someone can point out what would be the cause that is related to the TC replace. I know the whole transmission was pull, so anything be touched during the work?

Thanks a lot in advance for any advise!

PW

 

Also forgot to mention, sometime when take off from stop if I press gas too light, the car jerk too.
Also it doesn't happen when accelerating, or maintaining at constant speed.

 

I'm wondering if its breaking itself in after the rebuild. Manual cars with really toothy gears tend to do that.

 

The transmission wasn't rebuilt, only the TC, would there be also a breaking period from that?

Thanks

 

This could be the TC lock up solenoid, oil pressure or clutch. There are so many things involved in this area, it's a tough call but if I had to just guess, the TC adaptations are not right or the TC is not working right. You may need a trip to the dealer to reset the software.

 

Will the ECU reset work?

 

Still looking for solution.
On the other hand, although the CEL is not on, does anyone know if the CEL will be on upon any TC lockup event? or it come up after a certain count or duration of fault?
I am wondering that may be the rebuilt TC is faulty, but just not bad enough to trigger the code?

Thanks

 

Another incident today -
While leaving parking slot, the car didn't move due to one of the wheel got stuck in a pot hole, I press more on gas, then release, right away the engine stall. Would this incident be a clue of the jerking?

 

Just an update to keep the log so others can be beneficial.
After the engine stall incident, I did some test try to reproduce it. I press the brake all the way, with hand brake on, then put the tip in D, rev the engine to 2000 rpms then release, didn't stall. Give up after a few tries. However, right after I get back on the road, the pattern of jerking changed. First I notice it doesn't happen all the time when release gas pedal, and it's much lighter when it happens. Second the drive is lighter, better acceleration. I talked to the indy shop owner, he suspect that since the car was on the lift for 2 weeks waiting for the TC to be rebuilt, some carbon in the injection path could be harden, hence there be some clogs in the path. While I did my test, it may have shake some carbon off.
I am going to bring the A6 back to have a injection cleaning service ($125, seems to be a good price) and see what happen.

 

The car is smoother now. injection fuel line and throttle body was cleaned. Throttle adaption was done. Still occasionly jerks, but must less. Will go back to check the mounts.