C7_FINN

Hey so anyone have any update to this. I am having an issue with my '16 A8. The best way to describe it is that no matter what drive mode I am in, there are several noticeable "areas" where I see throttle hesitation, or in some cases, RPM drops in the order of 100-200 RPMs under steady acceleration.

Case 1 - Driving along between 30-60 MPH and step on throttle at 20%. RPMs dip 100-200 RPM and then the car resumes acceleration as normal.

Case 2 - Under 80% throttle between 3-4th gear and also 4-5th I believe, same 100-200 RPM drop right before gear change. Noticeable delay and speed decrease.

Case 3 - In Manual Mode (Paddle Shift), at WOT, noticeable surging at various RPM ranges. Makes driving on the track in manual mode almost impossible with the surging and RPM dips.

Took car to dealer several times now and they say this is just how the trans is set up on this car.

I tried uploading a Diablotune but it appears to still be having the same issue. I did take AFM off so no more V4 mode, which is nice, but the hesitation and jerkiness of the throttle is really irritating me. Any thoughts?

RussM05

Does it have a ported throttle body?

lakemg

Do you have any video to show us what it is doing?

Higgs Boson

the stock tune keeps the converter locked as much as possible. you may be feeling it lock or unlock depending on your pedal torque request.

this is a little different of a transmission than previous GM's. they tried to make a PDK with a torque converter.

robert miller

Some good info here this didn't know that at all. But can understand on keeping the converter lock as much as possible.

2016c7fl

the same issue I had with my 2016 Stingray Convertible. RPM surges and drops at various speeds as well as transmission shudder. Just had my torque converter replaced as well as all lines flushed and drained and it is now like driving a new car, just amazed at the difference. Started at around 8500 miles or so and just gradually got worse. Suggest you take to service at your dealer and jump up and down until they do the replacement.

C7_FINN

I published a video from last year. You can see that around 2800 RPM right before the last shift the RPM sags a bit, so much so that the tach shift indicator shows the blue line in some cases (when in performance mode - not shows in this video) even though shift hasn't taken place. It is even more noticeable when in A8 manual mode, as the car is so jerky that it becomes scary to drive. I feel like I'm dipping and then regaining hundreds of RPM through the band. do you guys this its the TC? It only has like 1000 miles on it.

C7_FINN

Posted here:


This isn't nearly as bad as it can be, but gives you an idea of where the problem area lies (around 2800 RPM and also another one a bit higher).

C7_FINN

Yeah, but why would it lock and unlock under constant pedal pressure. I'm under constant and even acceleration and it does it still.

C7_FINN

Other than an X-pipe and corsa extreme exhaust it's a bone stock C7.

Higgs Boson

It will unlock based on pedal %, torque request, RPM, MPH, etc.

If you are steady state pedal and cruising 50 MPH down the road and AFM is not going on and off also and the car is vibrating or surging then you have a TC issue.

In your video it looks like the converter is locking.

C7_FINN

OK, thanks for the rely for starters. However, I put in a diablo tune to prevent the AFM from activating, so it's always in V8 mode and the AFM valves never operate either, so that would not cause the issue. This video doesnt really show how violent the "locking/unlocking" you describe is, however. I was on the track racing, and the RPM dips were so abrupt that the tach indicator would show the blue line, which is normally reserved for shift changes.

I'm a little mechanically ignorant, but why would a TC locking cause the RPM to dip, wouldnt a locking TC cause the RPM to stabilize and then hold for a moment. I'm experiencing 200 RPM dips, and furthermore, it is under a pretty aggressive torque load. Not sure why it would be designed to even lock under the load conditions. It isn't WOT, but pretty close.