I stopped at a local Chevy dealer inquiring about a potential Z06 I was considering purchasing at another Chevy dealer that had a potential transmission issue, they said if the car had a tune and "aftermarket" control modules they wouldn't work on it.

So here's my question ... is there any such thing as aftermarket control modules when tuning a C7 Corvette (Z06)? Second question who are the reputable aftermarket tuning shop you all would recommend?

Thank you
Brian

 

First off, who is "they"? If it is the appointment clerk, aka service advisor, I wouldn't bother. Use him to make the appointment. I would go find the worker who is doing the job. Unless you have a blower sticking out of the hood, I have my doubts if the SA would even know. What do you mean "potential transmission issue"?

How much mods do you plan to do? Simple couple of things, DIABLEW. If it is radical stuff, I would prefer to get it on a dyno. Nothing against DIABLEW but that is my personal preference.

 

So the transmission has a hard engagement in to Drive and Reverse and the reason I went to my local Chevy dealer was to get an idea how much it would cost to R&R the transmission if it in fact needed to be repaired. That's when I was told that "if" there were aftermarket "modules" they couldn't do the work. They being the service manager and parts guy. I don't plan on doing any modification to the car if I buy it, I just want to know what I am buying before I make the purchase. The reason I asked about a reputable tuning shop is to contact them for any helpful information on C7 tuning that would help me understand what I was thinking about purchasing.

 

I believe they are thinking of the Transmission Control Module modifications. For example, I have done it on my 16 Stingray. I got a program and had it flashed for firmer shifts and I restore it to stick before I go in. Check with Diablew.

 

The only aftermarket module someone could add in place of OEM would be the suspension controller (ie from DSC) and it has Zero to do with the transmission. With HP Tuners, you can adjust the transmission as well as the engine but the physical parts are still OEM. Unless the car has a bunch of mods on it, all the dealer has to do is reflash it back to stock.

Other things someone may have installed would be a "Range Device" and/or a Throttle Controller. Those are piggyback items. Just unplug and remove them as desired.

If it's a full up race car, then you get into things like aftermarket ABS, MOTEC controllers, etc

As far as pulling the transmission.....$$$. The rear cradle needs to be dropped and it needs to be separated from the diff since it's a trans-axle arrangement. Then you have the actual cost of repair. At best they might give you a price range but there's no way to give a definitive number without knowing what (in theory) is broke. Figure $2k-$3k for remove/replace and then $x for the actual rebuild.

 

Didn't some early years have a hard shift?

 

Any Hard shift complaint should be addressed with the " GARAGE RELEARN process before even considering a rebuild !!

The stock A8 is a strong transmission and is behind some cars making 900 HP , it takes a lot to destroy an A8

See my post #4 ... about a Garage Relearn
A8 REBUILD QUESTION about PROGRAMMING - CorvetteForum - Chevrolet Corvette Forum Discussion

Dave

 

The appointment clerk didn't want to work with him so is he garage relearn a DIY process?

Side question. My TCM was flashed with the appropriate program then it was altered for a better shift. Supposedly it was an update for the 2016 MY. We downloaded the program and the tuner did something. Suggestions?

 

If you have the tool that can start the process, yes, it's easy, HP tuners and GM's GDS2 can run the process, there are other high dollar scanners like Autel and Snapon that can also do the Garage relearn process . if you don't have the tool, any competent shop can run the relearn on the A8. it takes about 35 minutes start to finish

I am assuming your Tuner is Diablo Lew he is a friend of mine and also tuned my C6 and C7 until I put the blower on

The Garage relearn has nothing to do with the " TUNE" ........

The procedure 1st puts the transmission in learning mode and will cycle all shift servos to learn what pressure/volume is needed and what is the release time for each clutch pack. The trans has to be up to temp before the process will start and foot needs to be held firmly on the brake pedal

It's imperative u do not try to end the process before it completes or try to drive the car, you could BRICK the TCM and leave your car stuck in Neutral.

The trans will make some pretty crazy noises that might scare some during this part of the test but it's all normal

After completing the 1st part which takes about 35 minutes, the Software with tell you the relearn is complete and the TCM is now in a learning mode, you now can shut the car off wait for about 10 minutes and then restart the car, this will allow you to drive car after the relearn,

For about the next 100 to 200 miles, The TCM is measuring the input shaft speed and output shaft speed during each gear change as it searches for the correct pressure to apply, and the correct release time for each clutch pack to make a perfect shift at every speed and condition it faces. this includes measuring engagement time when you first drop it into gear, if the TCM detects a harsh shift or engagement, it will make a correction for next time

It is very important during this " learning" time to vary your driving style!! You need to drive it like your fathers Buick at times but more importantly you need to drive it like you stole it and all points in between otherwise you might still experience poor shift quality.

During this time, you might experience a poor shift, harsh engagement, harsh down or upshifts, shift flair between gears, don't worry as all off this is normal and part of the relearn process

Any competent transmission shop that has diagnostic equipment (GDS2 is one, plus you need a GM MDI communications device) that is needed and knows how to do this process, if they don't know what you are talking about ... RUN , do not walk away as I would not let them work on my car


Dave
​​​​​​​

 

Thank you, I appreciate the information and feedback. I just needed to know if there was any possibility the car I'm considering purchasing "could" have non-OEM modules. At this point without knowing what was actually done to the car, I have to assume it still has the OEM modules with an aftermarket tune.

Brian

 

ASSUMING it does, perhaps a dealer can reflash all the modules to the latest spec and see where we go from there? Maybe it was hard shifting because the PO wanted it to bang that hard?

 

Yes he is. So here is what happened. The car was stock, I added Diablew's tune. I sent it for a coolant flush. After handing over the keys, I decided to have them check the modules for updates. I told them, per Lew's instructions to NOT touch the TCM or ECM. The SA lied. Thankfully, I backed up the ECM and TCM to remove the Diablew tune and restored it to stock. Somehow I missed the mechanic's call. When the guy called me to make me a deal of 2 updates for the price of 3, I again stressed that the TCM was NOT to be updated. Later on, he told me that although the paperwork said 3 updates, he only did 2 as per my instructions. Being the trusting sort, I meandered down to the bay and talked to the tech who admitted that he updated it by mistake. So while I will use that tech, I will try to avoid that glorified appointment clerk.

Diablew had me do a backup and he recoded it to the new TCM & ECM. Installed the new programs and it seems to be fine. So the question is this, IN YOUR OPINION:

1. Is that the best program possible that would prevent the damage of the transmission or should I try find a better solution
2. With the new program from Diablew, do you think it would incorporate any changes from the GM TCM update?

​​​​​​​TIA

 

1- I am not a fan of updating modules just for the sake of updating , if you don't experence any problems , there is no need to, module updates are sent out because of specific complaints about a problem
Doing an update, is like updating computer BIOS , u just don't do it unless there is a need . You know how many updates there are for the TV that you watch....no because if it works you are fine with it right? Just look at all the C8's that are having issues with over the air forced updating, sounds like a good idea but in reality it's not .

2- Updating modules just because does not extend the life or prevent damage, unless it's a pretty serious update
If that's the case , there would be a TSB or a recall issued

2- With GM module updates, anytime you get a module updated it will overwrite any old settings etc , so any changes that Lou made to the original TCM or ECM program would be replaced by the update . If you had sent Lou a new copy of your tune and TCM file after you had the updates done and he updated them , then you answer is yes it would incorporate any changes that GM made plus changes that Lou made. If he just had you restore you orginal backed up modified files then chances are , the old files overwrote the new GM file

But if there was nothing wrong with you car in the first place .... then you have nothing to worry about using the old file........

Remember, the Garage Relearn is NOT module update , it's a "reset" of the factory settings and a process that puts the trans in Relearn mode

Dave

 

Brian , you need to ask them their definition of "aftermarket " modules is

A normal C7 does not have aftermarket modules , it might have a modified tune for more power and if that's the case , if it's a GM dealer they can read what's called the "CVN" file and tell you if it's been tuned ( there is only one device that can modify a tune and not be detected but the chances are small that they used that device )

Only a highly modified C7 would have a aftermarket ECM , these units are usually reserved for full race vehicles or a serous street car do you would know instantly that it had an aftermarket ECM

If you are unsure, walk away , there are plenty of low milage c7's for sale everywhere ......

Dave

 

What is that device?

 

you own it .....

Dave

 

That is crazy. I would never have thought of the Diablo as being able to do that without leaving a trace. HP Tuner, maybe.

 

The Diablo tuners are the only device that do not alter the CVN file that is used to chexk to see the vehicle was tuned ...

I can personally verify this fact .......

Dave

 

Dave, I suspect our local dealer was not very knowledgeable especially when he said we don't rebuild transmissions we replace them with a GM rebuilt unit because you can't get parts for them. So, I went to the parts counter to find out what a GM rebuilt trans would cost ($5000) and I asked about specific transmission parts at which point he opened his computer file and saw the whole transmission part breakdown. He said "Oh I guess you can order parts from GM" and proceeded to tell me if the car had an aftermarket module(s) they couldn't work on it.

The only reason I went to the local GM dealer was to get an estimate on repairs, if in fact it needed transmission R&R so I can make an informed purchasing decision. I highly doubt the car has anything other than tuned OEM modules based on all of your responses which I VERY MUCH appreciate.

The car is still available, but I am continuing to look for other Z06's, this just happens to potentially be a good deal and exactly what I'm looking for.

Thanks Again!!
Brian

 

Awesome Good Luck with your purchase !