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Just brought my new-to-me 2017 Z06 home to California. Seller stated the car was stock, but when I rolled up to a CA smog station for vehicle registration, they let me know the vehicle failed smog due to modified software… the vehicle has been tuned and must return to stock before I can have a passing smog.
There is a Vengeance Racing sticker on the car, so I reached out to the shop. They were very helpful and let me know this car has a ported throttle body, 2.85” upper, Kooks headers and green catted X pipe, and an ECU and TCM unlock via HP Tuners.
Smog station said I passed everything, except for the modified software. Does anyone know if I can easily return the tune to stock (even momentarily) so I can pass CA inspection? I don’t know anything about HP Tuners, but is this something I can do myself or a local shop? Any recommendations for Ventura County?
At a bit of a loss here as I was stoked to start commuting with the new ride, and instead I have a vehicle not legal to drive in California.
The smog saga is over! I now possess a passing smog certificate and CA registration. I can finally start driving the Z06 for pleasure.
@Leroyt10 was 100% spot on. The car sat at the dealership for 6 weeks, and they insisted there was nothing wrong with the aftermarket air intake. They “called a couple GM engineers” and read the airflow while driving the car, and everything was supposedly normal. I finally bit the bullet and asked them to replace the intake with a stock one… $1300 later and I am back to factory intake. Almost immediately the CAT sensor was ready, so I drove straight to smog station with a PASS and immediately to the DMV after.
Thank you to everyone for the words of wisdom. Huge, expensive lesson learned about ordering inspections for out of state purchases, but at least I can keep the Z06 and start racking up the miles.
Weird! What Smog place did you take it to? The tuning shouldn't affect the I/M readiness and has nothing to do with it technically. Sucks! Hope you get this sorted..
On that note, the headers might be an issue and the secondary cats shouldn't be an issue since it's not monitored.. just make sure the primary cats are intact and no CEL.
It was a new law that Ca passed I think 6-8 months ago. It doesn't matter how squeezy clean your car runs. If the ecu's been touched thats it..
The only thing you can do is something like Procharger and get a complete setup that is CA smog certified, but who knows how long that will be allowed if it still is... or just do non-tune stuff like CAI, and after cat exhaust, but wont net much.
For now though I would see if that guy has the parts to go back to stock, IF he doesnt then see if he will kick down for replacements then have a dealer or the tuner see if they can put a stock tune back in..$$
I used to love doing my own mods, feeling the extra power, ect.. but once again the politics, drama takes out all of the fun.
I wasn't aware as this has been passed over a year already. Welp, no modification to the ECU unless it's CARB approved. OP, I would go back to stock and see if the dealer can flash it back etc.
I'm surprised it passed the visual. Usually that'll catch headers. I did have a 93 RX7 with the primary cat removed and it passed smog for 20 years. Inspection wasn't an issue as the car was so rare the inspector had no idea what he was looking at.
I wasn't aware as this has been passed over a year already. Welp, no modification to the ECU unless it's CARB approved. OP, I would go back to stock and see if the dealer can flash it back etc.
Hey everyone, thanks for the excellent feedback and advice.
I went to A & A Corvette today and met with Andy. Great guy, and awesome shop with lots of nice Corvettes parked in the lot. They looked at my car and noted my headers are stock after all, yet there was definitely a pretty aggressive tune still on the car. It does have a CAI and aftermarket pulley but smog station was willing to look past that on the visual. A&A Corvette thinks previous owner took off the headers and pipes prior to sale and never updated ECM. While I was excited for the full Vengeance Racing package to be on the car, I'm relieved to hear I don't need to spend $$$ just to put stock parts back on to make CA happy.
A&A had an HP Tuner on hand and had a stock C7 Z06 tune, so they loaded that up into my vehicle. No check engine lights or issues so far, and I'm going to drive it for a couple days and re-test at the smog station on Friday. No guarantee for a "pass" on Friday, but I will update the thread either way in case there are others that run into this situation. If the smog check still flags "modified software", my only option is to attempt a flash at the dealer, or install a brand new ECM.
Go and buy HP Tuners cable and software. Get it first, then once you have it download the current ECU and TCU tune files and save them to your computer. This will come in handy for later. Then go to your local GM dealer and have them flash the car back to the stock calibration on the ECU, this probably wont be cheap nor fun.
The next part will suck, once you get the stock tune files loaded into the ECU you will have to drive the car and get the drive cycles tests to complete. Once that is done then go down and get the car smogged and pass the smog test. Once that part is done then do back in and reflash the modified ECU file back into the car. Just to flash the ECU with HP Tuners will be $200 for the ECU, plus another $200 if you need to flash the TCU as well.
While some "stuff" is ridiculous, just like anywhere else these days, we sure do appreciate less smog than previous decades. And the beaches!
Except this particular CA law has nothing to do with less smog or clean air. Your car can pass the emissions test, but if it has a "tune" you still fail. That's the ridiculous part.
I think the idea behind the checking for a tune is that you cannot ensure the vehicle will not pollute excessively under all driving cycles when it has been tuned. Logically, if GM could have met all smog specs with the changes a tune does they would have sold it with those changes in the OEM tune.
Smog check stations don't have the equipment, resources, and time needed to do a full on manufacturer level smog analysis for every vehicle that is due for a check. That is why pretty much anything that can affect emissions needs CARB approval. CARB approval means the modification has been demonstrated to not adversely affect emissions. So those can be allowed during smog check.
AFAIK, no tuner has gotten CARB approval. Even if they did, how would the inspector know the vehicle being inspected actually has that tune and not another? To be sure an entire system to validate tunes would have to be enacted. Obviously that isn't going to happen so they just check and if tuned - fail!
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CA is very restrictive on what is allowed and you would think that those things would be an issue, unless they somehow had a CARB certification.
CA Smog Fail - Modified Software
