CA Smog = Checking ECU for Tunes

In that context I believe a BAR-OIS inspection is synonymous with a smog test for OBDII (and possibly OBDI) vehicles. Since you're a tuner, do you have any insight as to how the CVN is impacted by aftermarket tunes, Toyota TSB's, etc.? From the tire meets road article I linked, it appears that CARB/BAR have been building a database since 2015 that they will use to detect aftermarket tunes but since 3rd gens have been mostly smog exempt they will rely on the CVN.

 

I found this post relevant from a Honda Civic forum, specifically post #31 from Hondata (a manufacturer of ECU tuning hardware/software for Honda cars): https://www.civicx.com/forum/threads/hondata-carb-legal-tunes-and-race-flashpro.65895/post-1030262

Quoted text for the lazy:

So my understanding of what Hondata is saying is that even though Hondata specifically has CARB approved tunes, the current interpretation of how this smog test will check for a violation will still likely fail on such a tune.

 

The CVN (checksum)... to my knowledge is just a calculated formula that spit out this unique code.

Now to sort of answer your question... I know that when I scan my truck to check the CVN with modified software it's definitely different from my "stock" tune CVN. The CVN is just generated based off the values it reads on your ECU's data.

 

Thanks for the link. I've been meaning to search some of the tuner forums since they have way more numbers than us. Hondata is a big player in the Honda scene and has been around for a long time so I wouldn't discount anything he says. I think for the folks running CARB approved tunes, they may fail the initial inspection but they can then choose to go to the State Ref and show the CARB EO # for their aftermarket tune and pass the smog inspection that way. They might even drive away with a CA BAR sticker in their engine bay to show they're emissions compliant just like the guys with engine swaps.

 

So, when you go back to stock, the CVN changes back with it?

 

The software, data tables, etc. are stored in non-volatile memory (usually FLASH now). The checksum is computed by adding up all the values in FLASH. The result is usually stored in the last location. A processor (ECU) can do an integrity check of the FLASH by reading all the values, calculating the checksum, and comparing it to the last location.

There are different ways to calculate checksums. A simple checksum is not that great for detecting memory issues and also can be faked pretty easily. More rigorous methods such as CRCs are better for integrity checking and also harder to fake.

I'm not familiar with the particulars of the ECU, but I am very familiar with embedded systems. My guess is the ECU does the checksum calculation at power up and throws an error bit if it doesn't match. This is a typical integrity test for embedded systems. You can probably read this error bit state and the actual checksum value with the OBDII reader. I suspect this is what the emission testing people will do.

 

Yes... I flashed to stock read the CVN, back to my tune, then back to stock and the CVN returned to the same value.

 

Yes, the CVN would change with it.

What I'm not sure of is if they have a write counter of some type that keeps track of how many times it was programmed.

 

I hope the flash counter wouldn't matter...

Q: "Why was your truck flashed so many times?"
A: "Don't know... ask the dealer, my truck was having major issues since I bought it"

 

Is it not simple enough to just flash back to stock for the smog check? When they balk at the flash counts: "Yeah, I take it offroad a few times a year and flash a better tune for that". Or do you have to have a special permit/tag/tax for that too?

 

Not everyone flashed their own truck… tons of people paid someone else to do it

 

Lets hope the tuner can provide a locked copy of the tune and the user can just flash with the free flash manager. Thats essentially what I did even though I initially bought the flash kit.

 

Its like $350 now to do the software and cable.

 

Thats true. People would need to buy the cable as well.

So is it safe to say that in the event one needs to get smogged and they have the ability to flash, they can simply flash to stock, drive it for 100ish miles to have the system ready, smog, then flash back?

 

You don’t have to smog your truck for 8 years bro.

 

Starts tomorrow!

 

That’s a good point. I guess I keep forgetting how many are paying to have it done rather than doing it themselves.

 

So can you buy another ECU. Change the Vin and just swap em out.

 

You could if you have the coin

 

Its not about cost, its about control.