BarneyZ

I’d hate to discover that I had no factory warranty after it was too late. I wonder if it would show up on a PIP report?

Rebel Yell

I haven't read of anyone that has actually checked, but it's been talked about here for some time. If I was buying used I would have the car checked by my GM dealer, and then politely ask for a printout showing the car was OK. IMHO

BarneyZ

After thinking it through a little further, the tune might or might not show up on the PIP report. To be certain, I think you would actually have a physical test performed to confirm that a car had not been tuned.

Foosh

Yes, I've had the same question for quite some time, without a definitive answer. While it is clear that a dealer can check and ensure that the car has a current OEM calibration, what is unclear is whether they can do the forensics to check if it's been tuned in the past and later restored to OEM. That would also result in a warranty block in the case of engine failure.

Upon engine failure, GM asks the dealer to either send the data or the ECM to them for analysis, and that GM does have the ability to detect prior tunes. I don't know if a dealer actually has this capability.

Zymurgy

As I understand it, here is how it can be done:

Dealer can get the complete history of all the GM Approved Calibrations and CVNs (Calibration Verification Numbers) from the TIS2WEB site using the VIN and choosing the ECM.

Calibration Verification Procedure — Using the Tech 2®

Compare each: Calibration ID Part Number and Verification No. (Number/CVN) from your Tech 2® to the corresponding Calibration ID Part Number and Verification No. (Number/CVN) listed in the TIS2WEB GM Vehicle Calibration Information screen of TIS2WEB to ensure that they are ALL an EXACT MATCH.

If ANY of the Calibration ID Part Number and Verification No. (Number/CVN) when compared to the Calibration ID Part Number and Verification No. (Number/CVN) listed in the TIS2WEB GM Vehicle Calibration Information screen, DO NOT MATCH, then non-GM calibrations may be present.

Foosh

Thanks Zymurgy. Do you think the average dealer would do this?

Zymurgy

I would think they would if you paid them for their time at their labor rate. Don't see why a dealer would do it for free.

BarneyZ

Several years ago, when GM first started tightening up on mods, there was a TSB floating around which instructed the dealer as to how and when to perform a check for a tune, much like ZMURGY's post above.

Landru

Should be concerned, it's a valid fear and now's the time to know.
A blown LT1 costs beaucoup $s.

Heaven forbid a major $ issue occurs you can bet GM verifies tune first before repairs approved and IF it is/was tuned, whether you knew it or not = SOL.
Their rules.

Tell sales, "I’d hate to discover that I had no factory warranty after it was too late. adding "and any sale is contingent on proof.'

They balk, walk. YMMV

roadbike56

I didn't have mine checked before I bought. Back then, it wasn't even on the radar. If I purchased now, I'd have it checked. I'm not sure if they check it before they CPO a car. I'm guessing they don't. If they do, I'm covered as I purchased a CPO car.

Yaupon

Zymurgy, thank you very much for your informative post #5. Best explanation I have seen on the topic. Two years ago, a Raleigh, NC Chevy dealership charged me an additional $125 to essentially complete the procedure you outlined, as part of my C6 PPI. Base PPI was $100, plus the $125 or a total PPI cost of $225.

Foosh

I'm in the same situation as you w/ a CPO car. I also assumed they'd check it, but now I'm almost certain they do not do the forensics Zymurgy laid out.

My concern in the case of an engine failure is that they'd say I tuned it, even though it would have been done by the previous owner. We had a similar case here recently w/ someone who purchased a C7 from CarMax, only to have the engine melt-down shortly after. GM found a previous tune even though it had been flashed back to OEM and would not cover it, but miraculously, CarMax stepped up to plate and purchased him a new engine.

NSC5

Here are a couple of links that provide a little more about the basic process used by GM:

http://sandyblogs.com/techlink/?p=4248

and

https://www.corvetteforum.com/forums...-06-04-026.pdf

Avanti

I don't buy used sports/performance cars, period. Too risky for me since I have no close, perfectionistic, non-racing friends to buy such from (only ones I'd consider).

AORoads

That makes good sense.

phileaglesfan

It is a good idea unless you know the history of the vehicle. I was charged $100 to check my C6. It did check good but would you like to find out later your vehicle was tuned usually when you need the warranty?

Carvin

I recently brought a 2016 Z06 to Chevy for an inspection prior to buying it. I asked about checking for a tune and the service guy said they would.
The car had 3 unresolved minor recalls which they took care of so Chevy obviously still considered the car under warranty.

AORoads

^^^ You could very well be correct. Or not. Warranty/recall work can still be performed on other parts of the car where something hasn't been modified because very few cars are completely, warranty-blocked. If I'm wrong about that someone will correct me. Per the Zymurgy post above, it isn't a quick look in the files. If there's a tune it may/will have an effect on at least the engine if not the entire powertrain. But, you have to go by what you were told. If it were me I'd have asked for it in writing. jmo

NSC5

As AORoads stated, recalls outside of the powertrain will be addressed regardless of a powertrain warranty block and with very few exceptions so will any safety related recall even if it involves the powertrain.

At a very minimum GM will look at the calibration history as Zymurgy stated AND they may examine additional data going forward. I don't know about the current status of the 8L90 transmission controller but the controller used for the Allison 1000 series in the diesel pickups also stores a peak torque estimate which can be used to catch attempts to use "sensor fooling" devices which alter the data from sensors (MAF, fuel rail pressure, etc.) instead of flashing the ECM.

If you are considering purchasing a used C7 from a non-GM dealer for me it would be worth paying a GM shop to run the CVN history screen along with checking for any obvious powertrain modifications. If you are considering purchase from a GM dealer then include this process as part of your price negotiations since the actual cost of doing this for the dealership is minimal.

Vetteman Jack

If I were purchasing a used C7, I would certainly want the car checked for any modifications to the stock tune. It’s cheap insurance just in case something happens to the power train while under warranty.