Update:

First, sometimes these forums can be bad WebMD symptom checker tells me I have cancer all the time lol.

The snow has melted enough to get her out. I took her on the highway and set the cruise again. I'm definitely getting oscillations but it seems related to AFM. At 80 in V8 mode the RPM's are solid. I can get them to fluctuate though by playing with the gas. Meaning if I pump the gas in a rhythm I can get the RPMs to move about 200 rpm. It seems like the torque converter isn't locked while at cruise exactly.

When the car changes from V8-V4 I don't really feel anything but I do see the RPM's jump up by about 150-200 then V4 is displayed on the screen and the RPMs come down about 100. When switching back to V8 it does the same thing but not as much. It really seems related to AFM. The kicker is the car shifts great with the exception of the 3-2 downshift. It's still hit or miss but I still need to put more miles on the car.

I was reading somewhere with AFM the torque converter is designed to have play especially for V4 mode. Can anyone confirm this? I really have no other symptom of a problem than some rpm flux and a rough 3-2 downshift which might clear itself up. Even if I have a bad TC I probably wouldn't take it in until a problem arises. If I never read B&W entertaining thread I'd never be looking at the RPMs and I wouldn't haven't noticed them. I would have noticed the 3-2 downshift though.


Hi Everyone,

I've been really excited about getting my C7. With that being said I have been concerned about all the talk of the A8. It sounds like some of the members have had to have their TC replaced which seems like a fairly extensive procedure to be done on a new car.

After reading all of the posts by many members I wanted to see if I had any symptoms when I got the car. Here is what I've observed and I'm wondering what's normal and what's not.

The first night I drove the car the transmission shifted fast! I've never had an auto shift so smooth and fast ever! It is pretty awesome! The next day I took off work just to drive. My park to reverse and drive happens without problems. Everything seems fine there.

i jumped on the highway and set cruise control. I looked at the dic to observe AFM and when it occurred I couldn't tell it was happening. Then I tried to stare at the RPMs and notice any fluctuations. This is the part where I started to get a little concerned. I would say 95% of the time my RPMs were solid and never moved. There were a few instances though where the RPMs appeared to fluctuate by about 100 RPMs. It appeared to happen when switching from v4-v8 but it was hard to tell. I did capture it on the pdr as well but it's really hard to tell if the engine needed to apply more or less power to maintain the right speed and because of that the RPMs fluctuated. It did not bounce up and down like some of the videos show. I never would have noticed it if I hadn't looked for it. I also felt no shudder or vibrations. My natural reaction tells me it's normal and it isn't anything to worry about. I'm a worry wart though.

The one item I am concerned about is downshifting. With my previous C6's and the A6's I could downshift through every gear and know I would get the same reaction every time. With the A8 not so much. Here is what I observed.

When driving at a normal non-aggressive style I had the car in D and downshifted from 50. Going through the majority of gears everything felt right. The 3-2 downshift was not right. From 4-3 the engine and driveline were engaged as normal and slowing the car at a constant pressure/rate. When I shifted from 3-2 the car would lunge forward before regaining normal pressure/rate of deceleration. 2-1 feels great. The 3-2 is so unpredictable I have to brake harder to stop. It definitely has me concerned. It's almost as the rev matching is slightly off or the torque converter is letting go then engaging again.

It bothered me so much I decided the other night to go out and test it some more. When I drive aggressively the 3-2 seemed to start to feel normal. It did however have an instance of the abnormal behavior as well. It did seem to be improving though.

Here are the thoughts in my head. I only have 230 miles on the car. It needs to break in and learn my driving style more. The more I drive it in manual mode the more it will behave correctly. My car was built in the middle of December but that's no guarantee of the updated fix from what I've read. I plan on driving the car as much as possible because it's truly amazing! I know I have my warranty and I'll use it but I'm curious if the behavior is normal and if it will get better? Specifically the downshifts. As an FYI, in normal drive mode the car works flawlessly and is amazing.

Thanks guys!

 

Sounds a lot like mine, built 9/15 with 3600 miles. I do however have the delay moving when in reverse on first start of the day. I feel like the 3-2 shift issue is most likely rev-match over revving the engine to get any effective engine braking. I'm about ready to seek a local service advisor familiar with the C7. Really hope I don't have to do the TC replacement.

 

The tranny is supposed to "learn" your driving style so I would say for sure to drive and put more miles on your car driving in various conditions. Once it gets 500 miles on it, go for some spirited drives. My tranny is awesome when it is driven hard. Around town I do occasionally get some rough upshifts and downshifts usually 1-2 and 3-1. I have not noticed any RPM fluctuations at highway speeds. I am going to ask Criswell to evaluate my tranny when I take it in for the first oil change in May or June. By then I will have over 5000 miles on it as it has 3800 now and I am driving to the Bash next week so that will put another 1300 miles on it. My car was a very early '16 built the last week of June 2015.

 

my car is a early 2016 A8 I think your car needs more time.
The first 500 miles were strange at times the first 1-2 shift was delayed in auto. No issues now, the TC feels rock solid no rpm hunting. First 1-2 shift is normal, at startup the car will drop right into drive or reverse no delays.

 

I have a 2016 Z51 A8 with Mag Shocks. It really depends on what performance mode you are in... the shift programs change depending on how you set the car.

On the street, I set the car in either "Touring" or "Sport" depending on the road conditions... and use auto mode. But these change the shift mapping.

On the track I set the car in "Track"/Race mode and manually shift using the paddles.

I've had no problems with the A8 in any of these situations.

 

Could be the rev match at lower speeds and gears.

 

Just updated the top post.

 

I have noticed this every time when using manual mode that the rev-match causes the car to accelerate after a downshift. I was just at Spring Mountain last week and their A8 cars do the same thing -- although to a lessor degree (the two that I drove.)

I am left to wonder what is the purpose of rev-matching with the A8? With a M7 (or any manual trans car) you perform a rev-match to sync the revs with the next gear and smooth the transition. This is done when the clutch is depressed. On the A8, the rev-match is performed while the engine is still connected to the drivetrain. At times the revving is extreme causing the car to lurch ahead. I don't see how this can't happen. The engine add revs, the trans is connected, so the car moves ahead unless the torque converter is magically able to detect rev-match from stepping on the throttle and isn't doing it.

I am at a loss to understand the need for rev-match on the A8. When I am downshifting with no throttle input I expect the car will slow down -- not accelerate. Even when hard on the brakes and paddle downshifting for a corner there is more power coming through with each shift down due to the throttle blip. This is NOT a safe condition.

Is there a way to disable rev-matching on the A8?

I have been to the dealer twice and have been told all updates have been applied.

--Dan

 

I loved the rev matching on the A6 in my C6. The A8 does a great job in every shift with the exception of 3-2. The point of rev matching on the A8 is to allow for a seamless downshift, engine compression, consistent back pressure, and to keep the balance of the car the same. The problem with the 3-2 downshift is it offsets the balance of a the car. An example would be the 2-1 downshift. Completely seamless and no balance change of the car.

I am finding when I drive more aggressively though and downshift at a higher RPM it does a better job from 3-2. I really do think it's a transmission learning thing.

 

The downshifting on my A6 was unobtrusive and never accelerated when moving into a lower gear like the A8 does. There is no engine compression or back pressure when adding gas during a downshift. The balance is also thrown off unless under heavy braking. The system should also work at lower revs and less aggressive driving. On mine, it doesn't. In any downshift, in manual mode, with foot off the gas, the car will shift, rev-match, and accelerate -- sometimes a little, sometimes a lot.

All in all, it's stupid and I hate it. ;-)

 

That's a fair assessment. On the plus side, your profile picture is awesome!

 

I have a 2016 a8 stingray. When going into 5th gear at 45, it sounds like a bunch of marbles comming from the rear end. I have 13,000 on the car. Also, getting water in the back window channel, dealer said they have to clear the drain holes, really. Dont think i should be getting an inch of water ion the back window channel. My third vett, i think i am done with them

 

It's an RPM, and Speed thing.
When down shifting at "slower" speeds, and coming to a stop, is when I find mine also slightly over revs from 3-2, IF, I downshift manually.
If I'm zipping along at a good speed and downshift from 3-2, and NOT coming to a stop, it doesn't do that.
So I just don't downshift manually from 3rd to 2nd when going slow, and coming to a stop.
YMMV
As far as worrying about whether your trans is not working correctly, as in a problem TC etc.. just drive it and let it break in and learn.

You will Definitely know IF something is Really wrong with it.

I went through the same thing worrying about my A8 at first
Was always looking for anything and everything that might show me there's something wrong with it.
Finally I gave up worrying and drive the hell out of it.
The A8 really likes higher rpm's and now with over 14,000 miles on it, mine is still working great

 

[QUOTE=Smooth9883;1592031396]I loved the rev matching on the A6 in my C6. <snip>

Unless you had an after market unit you did not have rev match on your C6.

I put 128K miles on my '07 C6, using the paddles from the "git go" until I traded it.... no rev match.