Originally Posted by
gmtech16450yz
Ok, thought I’d chime in with a little info that might help…
First off I believe the “*” or asterisk that was mentioned is what comes up in TIS when the calibration “is not recognized by this release of TIS”. This does not necessarily mean it’s a not-GM calibration, it just means TIS does not recognize it. I’ve seen plenty of factory calibrations that TIS does not recognize or have in the database. I just did an exchange cluster yesterday that had two unrecognized calibrations with *’s next to the numbers. This cluster came straight from the factory authorized repair facility. *’s next to the calibration number does NOT necessarily mean it’s a non-GM calibration.
The TSB I think people keep referring to is 08-06-04-033. It tells you how to check for non-GM calibrations. It does NOT say anything about voiding the bumper-to-bumper warranty. Here’s what it says…
If a suspicious hard part failure is observed in the engine, transmission, transfer case or driveline, perform the calibration verification described to determine if a non-GM issued engine calibration is installed. Non-GM issued engine calibrations subject driveline components to stresses different from the calibrations that these components were validated to. Repairs to engine, transmission, transfer case and/or other driveline components where a non-GM engine calibration has been verified are not covered under the terms of the New Vehicle Warranty.
There is a newer bulletin, number PIP4558 (preliminary info, not a TSB) that refers to piston damage in ’07 and ’08 trucks and SUV’s with gas V8’s. Here’s what it says…
If a hole is found, perform the following steps:
1. Inspect the vehicle for aftermarket components, such as an exhaust or air intake system.
2. Document the ECM calibration numbers and related CVNs as outlined in the latest version of 08-06-04-033.
3. Call Brand Quality Manager, (deleted name and number) to review further direction. He may request photos of the damage or ask you to mail the damaged components to him for inspection.
Here’s my personal opinion on the piston damage PI in particular. I believe there are two things going on that may end up in piston damage.
First is most definitely aftermarket tuning. I am thrilled that we have these tools to manipulate the powertrain systems in these vehicles, but in the wrong hands these tools can do a lot of damage. You REALLY need to know what you’re doing if you’re going to try to change things like fuel and spark. I know there are people out there with these tuning tools that ARE causing damage with their settings and GM should not have to pay for that damage. There are warnings about modifying factory calibrations in both of the major tuning programs that should be taken seriously. I’m glad we have the tools, but any tool can do damage if used improperly.
Second possibility I would put directly on GM. I’ve scanned plenty of ‘07 and ’08 Gen 4 V8’s and I’ve noticed one thing, customers almost always run cheap gas and it shows in TONS of knock retard under all driving conditions. I think GM made a mistake telling people that all these engines are fine to run on 87 octane gas. Most of the V8’s have around 10.5 compression ratio and some V6’s are into the 11’s. I know fuel and timing control can allow that kind of compression, but if it can’t control detonation things can go bad really quickly. I believe GM should have put a “Premium Fuel Recommended” tag on all these motors. I tell every customer that asks, or people I know that have late model GM vehicles to run premium fuel always. In the 6.2 especially, you can hear them ping, which is telling me factory calibrations are not controlling timing well enough to handle the low octane fuel people are using.
I don’t know if the piston damage that GM is seeing is from cheap gas (especially in California), or aftermarket tuning. From the looks of the pictures in the PI, I’m thinking it’s more likely aftermarket tuning. (Pretty extreme damage.) Be careful with those tunes!
(Tried to post the pics from the PI directly from the GM site, didn't think it would work! I'll put them on my site and put a link to them later if I get a chance.)
GM to crack down on Aftermarket calibrated vehicles?
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