Walter Raulerson

My car'15 Z51 A8 Here are the problems so far: SEAT BELT FIX, COMPUTER MODULE, TRANSMISSION SHUDDER before 6600 miles. More problems with this one than all 6 before.

Jay_Davis

Had lots of those problems with the A8 in my '15. After 2 years of trying various things, they finally replaced it. The replacement is a lot better, although its still not perfect. I don't think this A8 design will ever be perfect.

R J Passage

I have a 2009 with automatic transmission, 42000 miles. I was going to get a 2018. With these A8 problems I think I will keep my 2009, unless someone can tell me for sure they have solved the A8 problem.

SRQStingray

Was offered a great deal on a 2017 black 2LT Grand Sport vert with A8, a stunning car. It came to nearly 20% off. I currently have a 2014 M7. After all I have read about the A8 on this forum and others, I walked away. I have had 47K miles of trouble-free driving with my M7 car. I can't pull the trigger on a great deal because I can't imagine dealing with a potentially flawed transmission. Top that off with the stupid V4 mode that I can totally avoid in the M7, I'll look for a new M7 after the New Year.

hypnotoad

Just got a P0700 code today on mine after I had the torque converter replaced a few months ago. The transmission had been acting much better since they replaced the torque converter but we'll see what needs fixing this time.

NSC5

Hopefully the codes will lead to a simple and fast fix. P0700 is a generic code request from the TCM to the ECM telling it to turn on the CEL and as an indication that one or more codes are stored in the TCM.

HIHO

My 15 Z51 vert with the A8 has never failed, but would over rev under a load. After letting up on the pedal, it would take several seconds to get down to the right rpm, this was in sport mode.

​​​​​​I just had long tube headers installed along with a dyno-tune. It now shifts faster, smoother and does not over rev. I was told there are over 300 settings that can be made on the A8 tranny. Also had transmission fluid changed along with filter ad the fluid had started to turn brown. I currently have almost 20,000 miles on it. The A8 works great now.

NSC5

That wasn't a fault but simply PAS/PAL mode going active. This has been a feature of GM automatic transmissions going back over 10 years and is intended to mimic the same behavior an experienced manual transmission user would utilize under the same conditions. Heavy throttle followed by a lift, particularly following or during a turning maneuver, initiates this part of the program and it holds the gear assuming similar driving behavior will continue. The RPM remains high because the converter is locked providing engine braking/engine control of deceleration as intended and it remains in the lower gear in preparation for immediate hard acceleration.

Putting the driver mode into tour mode makes this behavior less likely.

Your new tune just removed this intended behavior.

EDJ

Just bought a 2015 Stingray. 8500 miles. Had shudder, took to dealer, transmission fluid flush as per TSB. Only driven a few miles but seems to have fixed problem. Tried to add to spreadsheet but it would not allow me to enter year. Will update if problem returns.

dirty eddie

I have a 2015 corvette w/A8 trans, Vin 1G1YB2078F5100853, 6700 miles. At highway speed I get a 100-150 RPM flux and the dreaded rumble//shutter. Don't know how to enter info on spread sheet. Have an appointment with dealer next week.

Heidemarie

Our 2015 Z51 A8 had VIN ending in 846 (probably produced same day as yours) and this car had TC replacement at 8886 miles due to shutter and RPM fluctuation in V4 mode in cruise control (set at 45 miles) and rapid oil pressure fluctuations from 30 to 50 PSI continuously during shutter. New TC corrected this but we traded car in on a '17GS. Have no problems so far with the GS at 9250 miles. Good luck with your dealer appt. and TC issue.
Heidi
Save the Wave

markmo

My 2016 (built Oct 2015) was doing the same thing.

Took it to my servicing dealer for an oil change and told the service writer what it was doing. They "could not replicate the problem" but on my way home it was still doing the shudder thing. Called them when I got home and made another appointment and asked if I could ride with the mechanic next time. A week later on my way to the appointment my check engine light begins flashing within 5 miles of the dealer and the car is locked out of V4 mode. On the test ride, the mechanic agrees the car has an intermittent shudder and tach drop. They do a flush and tell me I need to put 200 miles on the car before we can go to the next step. On the way home from the flush, the check engine light began flashing again before I was half a mile from the dealer. The day after the appointment the weather turned stormy and the salt spreaders were out in full force. I have not been able to drive the car since that October appointment, consequently I have not put the 200 miles on it. I should mention that this car has 4900 miles total. Anyone else have the flashing check engine light? Did you find out what the cause of this flashing light is?

Mark

BTW: Several months ago I wrote in the survey that I had not experienced any problems. Obviously that's no long the case.

NSC5

Mark,

The flashing CEL indicates a sustained engine misfire condition for one or more cylinders and not is separate from your transmission problem; V4 mode is locked out whenever the engine isn't operating as intended.

The dealership needs to immediately address the flashing CEL situation because this can result in dumping raw fuel into the cats which can quickly damage them and in extreme cases the overheating is sufficiently severe to create a fire hazard. The flashing CEL is an indication that immediate action is required unlike a steady CEL which often indicates a less serious issue.

If you get a flashing CEL immediately reduce engine load and if the flashing CEL stops you can safely drive it in for service. If the flashing CEL continues it should be parked and taken in for service on a flatbed. Never continue driving with a flashing CEL.

GTRSOLO

I can't believe GM hasn't just done a recall at this point, other than for the obvious reason.

markmo

NSC5,

Thank you for the quick reply. I didn't realize the flashing light was so critical.

The flashing CEL came on moments after I left the dealership. I pulled over and turned the car off so I could call the service dept. My call went to voicemail so I restarted the car and was going to head back there, however, the light was out. I drove home (25 miles) and the CEL never came on again.

With the weather such as it is in upstate NY, I wont be able to follow up on these issues until late March or early April.

NSC5

Mark,

You are welcome.

It could be as simple as a loose plug wire/connector or a failing coil pack and these are the most likely reasons for a flashing CEL. An injector that is clogged will also cause this and would potentially be the safer form of misfire since it doesn't dump raw fuel into the cats but a partially clogged injector can result in a cylinder running too lean which can lead to engine damage.

Since it went off and didn't come on again during your drive home it is a marginal failure so no harm was done. Part of the engine control system precisely and continuously measures the crankshaft speed and it sees the slight change in speed as each cylinder fires and when the expected change in rotation speed doesn't occur then a misfire is registered for that cylinder that is not providing the proper contribution to crankshaft speed. The CEL won't come on until several misfire events occur within a short period of time to avoid nuisance CEL illumination so to get a flashing CEL there was a sustained misfire for one or more cylinders. Stored within the ECM is a misfire count by cylinder that your dealer can retrieve (and should have retrieved when it happened on your way to the second appointment). The stored data will show which cylinders were affected which should make their troubleshooting fairly simple.

rb185afm

33,981 miles & I can add my A8 to the problem list
Wife was driving her base 2016 A8 to work this morning. 70 MPH on the freeway and engine light popped on. Codes show P0700 (trans control system malfunction) and P0711 (trans fluid temp sensor). Now I get to wait a week and take her into Able Chevy for a cure.

Blu-Beast

mine did the exact same thing yesterday and its only 25k miles

Mr. Jones

Look at the bright side.
I had the TC problem 2016 early production-missed the last TC update.
They flushed it and it good so far.
The bright side-I can't spend money on Mod's because I have to keep
my warranty in tact
GM not going to do any recalls
just fix them as they come in.
likely my last GM car.

markmo

Sounds like your car was built around the same time as mine. I also missed the TC update. My exact symptoms were as follows:

With cruise set at 55mph in auto mode, I would get a slight shudder every (approx.) 6 seconds that would last about 1 second. Also tach would drop between 100 and 150 rpm with each shudder.
I have not yet been able to put on the 200 miles since my flush but on the ride home the shudder was a lot milder although still present.

Question: How many miles have you put on since the flush?