HighBeta

Actually, these torque convertor issues were fairly well discussed on this board - including the belt replacement need(s).

vdavenp802

Yeah right. Also discussed is tire wear, but that doesn't mean anything.
Proof, whats your source and documentation? Huh?

NSC5

What you do with your car is of zero concern to me but to get you started on your documentation you can start with GM's current TSB which is at least the 6th one they have issued in a series to deal with the issue of torque converter clutch shudder since the 8L90 was released: http://www.corvetteactioncenter.com/...tate-1324.html

And "the Google" is free, do your own research...

Mike Jesse

My Z06 has never gone into V4 mode, my Stingray OTOH would switch back and forth frequently.

HighBeta

Exactly!

IM3CPO

I tried a Range in my 2017 Z06 and it caused a CEL (and subsequent limp mode) after a couple days use. I even sent it in the Range to get it "updated" but ended up with the same issue, so I ended up returning it.

I decided to try the DiabloSport version of essentially the same thing but just ordered it today. I am crossing my fingers that this works as I seriously HATE stinking V4 mode!!!!!

NSC5

Range recently came out with their newest update (maybe a month old); I wouldn't be surprised if Diablo is still selling one of the older versions. I haven't followed that closely since my 2016 was fine with a previous update but check on the general forum and I believe the 2017 and 2018 owners are doing fine with the newest version.

What I did with my Range prior to the update was to turn it on after the vehicle was started since the only issue with it and the 2016 was an infrequent random communications issue at startup interrupting transmission to engine communications. When the ECM and TCM cannot communicate the 8L90 goes into its default protection mode locking into 4th gear in the forward range, this is used to protect the transmission when its controller cannot communicate with the ECM in order to request torque reduction like what you experience at full throttle upshifts.

The 8L90 is a very good transmission that causes very few issues in the Z06 and if it weren't for it frequently being exposed to V4 mode in the base Corvette there would be very few complaints with it in that application. There was an early update that addressed a fluid drainback issue that causes slow engagement during the first start after it sits for a long period of time but this was more of an annoyance than a serious problem. There were programming updates to address some operating quirks such as an initial rough 1 to 2 shift and this issue is much improved after the new calibration and can be completely avoided, if one finds it sufficiently bothersome, by putting the transmission into manual mode with it stopped and paddle up to second and then back to first and then go back into drive and operate it normally. Apparently with some Corvettes it was more noticeable than others but I have never found it bothersome with my 2016 Z06 although I can tell a difference with that initial 1 to 2 shift if I first go through the paddle routine before pulling out of the driveway.

It isn't unusual for the manufacturer to update calibrations, especially with a newly developed transmission and even an ongoing design coupled with a new engine will exhibit behaviors in the field that call for calibration updates. So it isn't surprising that the 8L90 had some calibration updates but those don't mean it is in any way a bad transmission. I am getting ready to order a new GMC diesel pickup and it will have virtually the same Allison 1000 series 6 speed auto that is in my 2006 GMC which is nearly identical to the original 5 speed used in my 2001 (GM didn't bother utilizing the second overdrive capability when they first adopted this transmission). Yet for the 2017/2018 diesel pickups with the newest Duramax diesel engine there have already been at least two calibration updates for the transmission to provide better operation.

The 8L90 in the Corvette application provides a great transmission and with it not being crippled via the AFM/V4 system it is very reliable. Certainly some 8L90 transmissions fail but that is true of every transmission, engine, and other component ever made. If you take out the AFM induced torque converter issues then the complaints about the 8L90 are no more than any other automatic GM has produced and far less than many.

And some of the other complaints are sort of humorous as in one thread in the general forum advising people to buy the M7 instead of the A8/8L90 because the Porsche PDK responds more quickly to paddle input than the 8L90. It is true that there is a slight delay between paddle input and shift completion which is based more upon a delay in how the BCM determines that the requested shift won't result in either engine overspeed or insufficient RPM to produce the required power rather than the ability of the 8L90 to shift quickly. AND the 8L90 is still faster than the M7 can be shifted manually so using the "slower than a PDK logic" it would make no sense to buy any Corvette given the extreme slowness of M7 shifting compared to the PDK-a logic that isn't logical.

DougDavis

I spoke with them today right before ordering my AFM Deactivator. They still recommend unplugging if you aren't going to crank the car for a couple of weeks. I will solve that by attaching a battery tender if I'm going out of town. Luckily the C& tender came with my 2019.

The T-man

_________________
Is this really true, not the sarcasm, which I appreciate, but the torque converter behavior?!

pkincy

Yes, true. Also DS may spoof the CVN so that a quick CVN check will not show a nonstock tune, but GM has ways of checking past that with the pcm still in the car. Several folks on the ATS-V forum have had warranty blocks initiated after they went in with a tune that spoofed the CVN and was removed prior to the attempt for warranty work. I suppose GM is putting more emphasis on the turbo cars because of the extreme hp increases you can get simply with a tune, but if they are checking harder on those cars I can't imagine that we won't see that trickle into the Corvette crowd. The Cadillac ATS-V doesn't use DS but a similar handheld system with similar CVN spoofing capability.

C7/Z06 Man

I have never heard of a "DS" tune being discovered by GM if the tune was removed before service (do a search here and I think you will find that to be true) now for any other brand of hand held tuner that may not be true along with HP Tuners.

pkincy

CVN spoofing is a relatively simple process and has been used by a number of tuners and sellers of tuning software. If the CVN is spoofed the pcm does not show a history of reflashing as the computer thinks it is the stock tune. And in fact no record of the flash is recorded in the 10 reflash history in the PCM. However the Global Diagnostic System 2 (GDS2) which replaced the Tech 2, has been given the ability to tell if a vehicle has been tuned without reading the simple reflash table (based on CVNs) that GM previously used to check for non stock tunes. I agree that we in the Corvette community have not seen an instance of a warranty block yet based on this new ability but there have been a number of warranty blocks reported on the ATS-V forum. Remember with a turbo car a simple tune can add quite a lot of horsepower. If you have a V2 from EFILive you can pull the reflash history on your car based on the CVN just as folks with the Tech2 and early GDS2s could. However the warranty blocks have come with no reflashes shown in that 10 reflash history table. So updated GDS2s have some added ability to check for tuning changes to the stock tune other than simply looking at the reflash history table.

Whether or not CVN spoofing will continue to work for Corvette owners, I don't know. But anybody tuning their car should be ready to pay for any warranty repairs out of pocket. If they don't get caught well they got away with something. But I don't expect GM is going to be happy being fooled into paying for warranty repairs on tuned cars. Looking at the reflash table was simply their first procedure for checking the tune. Don't think that somebody at GM hasn't figured out a way to check the tune past that simple reflash table.

chucky7

While in Manual mode, it is disabled.

V Vette

Many of these same gals/guys on another tread said you cant have enough HP (500, 600, 800, Zr1 etc) but how many are the same here who want to save a few pennies or use eco mode? Just people who want to argue..

Parcival

Drive to dealer and trade in for an M7 (srsly, that's what I did).

I wasn't one who was part of that argument.
But while I was at trading in the A8 for an M7, 460 hp wasn't enough... but 650 hp@crank stock is!!
And I still use Eco when I want, infuriatingly to some here!!