nypapaya

Hi,
I own a 01 2.7T auto with 76k miles on it.
6 weeks ago, check engine light on with the code 0741 for torque converter lock up, I bring the car to local indy right way, they did the follwing -
1. sent the TC to professional shop to be rebuilt.
2. While installing the rebuilt TC, drop the pan, replace all ATF (Audi original) (est. 7 bottle) and filter and gasket.

Right after I pick up the car, I feel the something different with the car. When I release gas pedal, the car will jerk. Mostly happen in rpm below 2000 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 and no fauty codes, except "0421 Warm Up Catalyst Efficiency Below Threshold (Bank 1)" . They too can feel the jerk but can't explain it.

The car has done tune up service (so all plugs and cables are new) 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
__________________
2001 Audi A6 2.7TT

Just Me

What do you mean by jerk. Driveline lash is normal, but you say it is different.

I dont feel i understand.

But if it changed, and they just did a tranny repair.................

Take it back and document it in writing.

G

Redneck Truck

Is it a jerk forward or a jerk back? Maybe it's just at the right RPM to shift into a higher gear when you let off and the jerk you're feeling is a crisp shift.

SloopJohnB@mac.com

The jerk is likely a problem with the TC lockup function. Keep at the transmission shop and have them temporarily disable the lockup function (disconnect the connector or vag-com log it) and drive the car...if the jerk is gone, it's the TC lockup.

Sounds like the rebuilt TC wasn't done well.

nypapaya

Thanks for the reply.
I should say like a small "bump" or a "thump", you feel something in the front "bump" a little when ease off the pedal (sometimes even lightly ease off when in low throttle position) . One of the mechanic think it's the engine mount, then another senior mechanic in the same shop take a look and he decided to call the TC rebuilt company to send a guy over. But they check out that everything with tranny/TC is fine. The owner of the shop then sent the car to a transmission special shop to test, that also check out fine.

All these were the condition a week ago.
Update 1:
This week the jerk is lighter, all of the sudden, just when I start the car one day and drive off, I immediately feel the condition change to better. Symptoms still there, but better.
Update 2
I did a injection line/throttle body/ throttle adaption couple days ago in the same shop, the car did gain some power back, the jerk symptom remain the same as in update 1. However, the MPG is decreasing since the event in update 1 happened, at least around the same time. On the freeway it's about the same, 22~24 MPG, local driving under 40 MPG decrease to 10~13 MPG from 17. I know all the works done shall not be relate to this. the "Warm Up Catalyst Efficiency Below Threshold (bank1)" also shouldn't, as I heard unless the catalyst converter is almost completely clog.

Just Me

which means your diagnosis of the jerk may be incomplete.......


hmmm what do i mean :-)

SloopJohnB@mac.com

Chrysler had the classic problem of inconsistent TC lockup and/or release and called it a 'chuggle.'
To this day I've not heard a better or more onomotopoetic word for the symptom.

A competent transmission shop should be able to disable the TC lockup function temporarily (it won't damage the transmission or lockup) and see if the chuggle disappears. That is the sine qua non test. Without which not the TC lockup be tested.

SloopJohnB@mac.com

Good one...but I'm not throwing stones at car jerks...they often bounce back at me...LOL.

nypapaya

I am going to try that during my next visit.
One question that I have in mind for a while, why wouldn't I see the TC fault code if the problem in TC? I am guessing that there is a normal "range" that the problem I am having is not out of it yet?

nypapaya

The problem was found.
When the indy replace the TC, they put in 7 L of ATF, as it's all that came with the ATF kit. however, since TC itself need about 2, so that's what caused the jerking - hestitate of lock up, and bubble.
Now my next question will be, was 2L a lot? I have driven with the missing 2 l for about 500 miles, shall I replace all the ATF again?