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The CVN is a calibration check digit sum that must match the manufacturer's original check sum when the car was EPA certified (or with any rev roll the mfgr registered with the EPA).
Every (any) invasive ECU intervention rolls a CVN so the check digits will not match the original factory entries.
This is not meant to rain on anyone's tune parade, just to educate you to "BE SMART" when you go these routes.
On the CVN, I do tunes using HP tuners, as a hobby, NOT as a business, and I DO NOT charge for ECU mods I do. For kicks I searched a CVN on a car that I tuned a few years back. When the car was sold the ECU was restored with the original ECU data. I recently checked its CVN and verified it contains the factory check digits. If this particular car ends up in CA or CO (and god knows where else soon), at least I am comfortable the CVN will pass muster.
BOTTOM LINE - If you're going tune, think it though...this is 2021 now!
CA and CO will check these CVNs. If they do not match factory CVNs - REJECT! Other states will follow.
2025 Lucid Air Grand Touring, 2022 F-150, 1926 Rolls-Royce SSG roadster
For what it's worth, back in 2019 when I brought my 2018 GT coupe in for some recall the ECU was re-flashed. I was told there was a change in the ECU so that it would remember all prior modifications to it. I don't know if that's true or not, but it is what I was told. I reported it here at the time.
For what it's worth, back in 2019 when I brought my 2018 GT coupe in for some recall the ECU was re-flashed. I was told there was a change in the ECU so that it would remember all prior modifications to it. I don't know if that's true or not, but it is what I was told. I reported it here at the time.
Yes, the factory can roll a rev anytime and the EPA recognizes that as a legitimate new CVN...but NOT unauthorized rolls.
In the case of my illustration - this VIN was from a 2009 MY car. The latest AUTHORIZED ECU CVN is 0000A5BE described as "new software for start of production: meaning in all this time, this particular ECU was never revised since the beginning of production. It is the CVN CA/CO will look for in emissions inspections of this particular car MY 2009. If it sees anything else, it is automatically rejected - failed emissions.
Different car, but an example of a very recent CA rejection for ECU tampering is this one - a used car that was purchase by this guy 2 years ago with a modified tune and he didn't even know it. When he first registered the car 2 years ago it passed CA emissions, but now this next emissions test he failed BC of the ECU tune.
Ok, ok, I guess I'll be the first charitable individual to step forward and buy a modified car off of a CA resident, at a discount, to help them out of this terrible predicament they are now in.
“Tuned” cars are often more efficient and get better mileage, including less emissions. In this age, it makes perfect sense that it fails because of some bureaucratic formula.
Getting eurocharged stage 2 tune with down pipes and new air intakes on my amg gtr today.. im in Indiana where they dont care about what u do to your vehicle
“Tuned” cars are often more efficient and get better mileage, including less emissions. In this age, it makes perfect sense that it fails because of some bureaucratic formula.
Yes, this is often true. 97% of the time, even an aggressive driver on the street is in closed loop where fueling is stoic - 14.7:1. The way fuel trims are managed this is necessary for a tuner to maintain. All of the tune gains come in PE where the other 3% of driving comes in; 1% or less for us "slow pokes" on the street.
I cannot recall a factory tuned performance engine I've seen where fueling in power enrichment (PE) is not what tuners call "pig rich". This is intentional by the factories and done for engine longevity. It is one of two main areas tuners hunt for extra HP/TQ and ALWAYS find them. The other area is spark timing. In the GT platform it is pretty easy to find 60-80HP without trying hard. It's in these fueling areas where raising AFRs in PE causes a more complete burn thus better emissions, but at the expense of engine life.
I've used wide bands and recorded AFRs on NA engines in the 11s, even a couple of times the high 10s. If it is an NA engine, the sweet spot is often 12.5. So I will modify injector data when I'm tuning and data log until I can see 12/12.5 then head over to timing. FI engines like the M177/178 are coming from the factory high tens, here the sweet spot is more like high to mid 11s on modest boost.
Looking at the rest of the emissions report above it appears ALL of the actual emissions test yielded passing results. This is too bad!
Last edited by Acta_Non_Verba; Aug 23, 2021 at 11:01 AM.
Does anyone know if the "restore to stock" flash on a handheld tune will roll the car back to the original CVN or if it roll a non-compliant one?
I would also like to know the answer to this question. I am in IL so dont know when they will jump on this CA BS but I am sure they will. Actually have to take my GTS for its first Illinois Air Test real soon and I will leave the Flashed Tune and see what happens, all they check in IL currently as that there are no Emission related CEL codes and that all systems that are monitored are ready.
I was thinking of doing down pipes and of course that will have to have a separate tune in order to not monitor the O2 readings but now with Cali Cartel leading the way into more scopes into our cars and tuning I hope IL doesnt go the same route.
Getting eurocharged stage 2 tune with down pipes and new air intakes on my amg gtr today.. im in Indiana where they dont care about what u do to your vehicle
Except if you are in Lake or Porter counties of Indiana. Then yes you have to go get vehicle emissions tested.
And we all thought the 91 gas was bad enough. The liberals are out to destroy Cali.
They have succeeded...We have a home in Laguna Beach that we rent to highly vetted people to help cover the taxes. Such a beautiful state, too bad the jokers running it have run it into the ground.
So what happens with these previously tuned cars that will not pass emissions? What is the solution? Certainly you don't have to sell the car out of state, do you?
Dealers are flashing back the factory data if the owner has lost contact (or if he/she never had contact) with the tuner. And that would depend if the tuners have and saved a copy of the original factory tune.
The guy whose failed emissions report is shown above was quoted $450.00 to reflash the factory ECU data. Apparently, CA car dealers quickly came up to speed on this one.
The above sounds easy if the tune was simple and did not support other mods. An example, the 09 I mentioned in the first post started out as an NA engine. It was supercharged, fuel injectors doubled from 40lb to 80lb, intercooler added, boosted fuel pump, etc., there was a lot of data I changed from the factory tune to get the supercharger running correctly at a modest 8lbs. That particular car was reversed and changed back to a factory NA motor before the car was put for sale, and I reinstalled the copy of the factory tune I had (and still have) in my library. It was the example I tested to see if the reinstall would relist the factory CVN which it did.
I'm making this point BC, if this car existed today in its modified state, and I simply reloaded the factory tune to pass an emissions inspection, I could do that logistically, but this engine with a SC, big injectors, etc. wouldn't even start on a factory tune.
I'm hoping my message, intended by starting this thread, is everyone becomes aware of fast changing consequences and just thinks through their builds, where they are located, how they might have to react if state laws change, how/what needs to be done to reverse mods to emissions test or even sell the car someday. Dealers, for example are more and more refusing trade in cars that have emissions mods BC they become the dealer's responsibly for the EPA penalties. Some states now require the dealer to provide a new/good emissions test to resell a used car, so the dealers are getting stuck with modded cars they cannot pass.
You do have to wonder if the idiots ‘rolling coal’ have forced the EPA’s hand in this. There is nothing more damaging to the environment and to people’s health than mass quantities of filthy, poorly combusted diesel spewing from exhausts.
You do have to wonder if the idiots ‘rolling coal’ have forced the EPA’s hand in this. There is nothing more damaging to the environment and to people’s health than mass quantities of filthy, poorly combusted diesel spewing from exhausts.
Yeah, the EPA took its first big-time bite of the apple with the diesel tuners.
Quite a scandal with Punch It Performance - EPA fined them $850,000, confiscated all of their "software". The owners tried to take the money and run...didn't work out too well...
One "out" these tuners use to have was the term "off-road use". All they had to do was publish on their WS the defeat device was for off road use only...not anymore.
In addition, SEMA warns that selling any aftermarket parts with the disclaimers "for off-road use only" or "for racing use only" is "essentially meaningless... if the part can be installed on a highway vehicle."
If you have the MyGenuis handheld programmer, I assume you could flash back to your factory tune, get emissions, and then re-flash the performance tune ? Or will he checksum have changed, I assume its restored if you have gone back to the factory tune.
So, I'm following day to day updates on a few other forums Re: this CA emissions ECU Mod check that went into affect July 19, 2021.
Just today:
If the company that produced the aftermarket part, or, the tune company that supplied the tune has a Carb EO# accepted or issued by the State, then their exemptions (including the tuner's CVN check data sums) will be in the state's DB...that according to the CA BAR.
One other guy in CA who did the same thing with a pretty big build and an HP tune, reversed everything and reinstalled the factory tune (like I did). He took the car in the next day for an emissions test so he could sell the car and it passed, so in these cases the CVN was restored to CA liking.
One other concern though - the test I and the guy above did were both 09 MYs. One thing that is known across all manufacturers, in later years, certainly in the range of AMG GT series, mfgrs started adding rev counters in the ECU. It is unknown whether CA is checking the counter. Shouldn't make a difference if the CVN is restored, but no one currently knows.
To Realien's Q in #18 - Pretty much every handheld I've ever had experience with does a copy/store of the original tune before it will load a custom one. All handhelds I've seen have the option to restore the factory tune which should satisfy CA for a test. Additionally, a few (like Diablosport) have a CARB EO# for 50 states on one of their handhelds and according to what a member on another forum said, the CA BAR states that flash would pass their test.
So, I'm following day to day updates on a few other forums Re: this CA emissions ECU Mod check that went into affect July 19, 2021.
Just today:
If the company that produced the aftermarket part, or, the tune company that supplied the tune has a Carb EO# accepted or issued by the State, then their exemptions (including the tuner's CVN check data sums) will be in the state's DB...that according to the CA BAR.
One other guy in CA who did the same thing with a pretty big build and an HP tune, reversed everything and reinstalled the factory tune (like I did). He took the car in the next day for an emissions test so he could sell the car and it passed, so in these cases the CVN was restored to CA liking.
One other concern though - the test I and the guy above did were both 09 MYs. One thing that is known across all manufacturers, in later years, certainly in the range of AMG GT series, mfgrs started adding rev counters in the ECU. It is unknown whether CA is checking the counter. Shouldn't make a difference if the CVN is restored, but no one currently knows.
To Realien's Q in #18 - Pretty much every handheld I've ever had experience with does a copy/store of the original tune before it will load a custom one. All handhelds I've seen have the option to restore the factory tune which should satisfy CA for a test. Additionally, a few (like Diablosport) have a CARB EO# for 50 states on one of their handhelds and according to what a member on another forum said, the CA BAR states that flash would pass their test.
So another update from another forum today (turning out to be a day to day saga)
For the poor guy whose failed CA emissions test appeared in post #3, he had a CA dealer reflash the factory ECU data tables to get the correct CVN. He thought he was out of the woods and has scheduled another emissions test for tomorrow. Unfortunately, as he was driving around yesterday a CEL appeared. Turns out the tune wasn't the only mod. The previous owner had also deleted the cats and it has a CAI installed as well.
As any tuner knows, when you delete cats, the rear O2 sensors must the turned off in the tune so they don't CEL. Well, of course, now that the factory tune is reinstalled, the rear sensors, which are missing, cannot report back...so, the CEL. Now the owner must reinstall cats for his year car and it turns out CA required 2 sets of cats (4 in all) that the factory actually issued a mandatory emissions recall in those years (I know as I owned one of those MYs).
Owner is now looking at "all avenues" one of which is possibly pursuing the previous owner in a civil lawsuit to make the car (and him) whole, which is to mechanically restore what he believed he purchased two years previously.
My message remains the same: THINK THROUGH YOUR MODS to the end before you start!
I love performance mods, I tune myself, I don't want to discourage anyone from pursuing their performance visions, just hopefully make you more aware of how fast things are changing.
Been emailing back and forth with some providers, and here's what I've learned (names abbreviated for some degree of obscurity):
RT has claimed handheld "flash back to stock" function will leave no footprint or trace in the ECU.
EC says they are unable to promise that their handheld will do the same, and would require the ECU be sent to them to make the numbers match (the HH cannot do this).
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
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