California Will Start Testing for ECU Tunes During Smog Checks Starting Next Week

[siggy]

Things get more complicated.

https://www.roadandtrack.com/news/a37022836/california-ecu-tune-during-smog-checks/

[prisonerofdoom83]

Obd1 would be exempt??

[nando]

yeah, they need a CVN#, which is literally just the checksum, to compare it with. They don't have any of that for the E30 or E36. If you look at the Daten files, only cars like the E46 and later even have them. They've been planning on this for decades, but it was never implemented.

Funny enough I've planned for a while now to force the checksum to match the stock flash and CVN#. I guess I'll have to make that happen now. It's actually fairly simple to do, you just pad the data with bytes that are pre-calculated to target a specific checksum result. If they are going to include the OBD2 E36 it would still be easy to do.

I wonder how this goes against the right to repair Executive Order. Technically, any modifications to the software at all are illegal, especially if you have to bypass a signature check to write unsigned files. But there are legitimate reasons, aside from just tuning, to be able to flash your own software. BMW of course only wants dealers to be able to do it.

On the other hand, maybe it'll make those stupid fucking burble tunes and coal rolling bro-trucks go away.

[siggy]

That’s a relief. I’ve been running the 2.7i setup on my 86es for many years now.

“They don't have any of that for the E30 or E36.”

[prisonerofdoom83]

That’s a big relief . I am finally so close to putting in my s50 swap bf was hoping to do the whole BAR test . Reading this was kind of ruining my day . But I think it should be okay

[nando]

I don't think you can even read the DME software with OBD1, definitely not with Motronic on the M20 which isn't technically OBD at all.

They started requiring manufacturers to report the CVN - I guess "carb version number" or something - around the year 2000. Which again, the CVN is just the checksum. I don't know this for 100%, but I don't think they have all the tunes in a database or something, there is just waaaay too much complexity there. There are thousands of individual tunes and software revisions for one BMW model alone. So they can't do a bit by bit comparison. All they need to do is read the checksum of the DME and compare that with the database value. If they don't match, you fail.

Actually, after looking at the daten files real quick - I'm pretty confident they can't do it before a certain date, because the DME won't be able to respond with the right information. Here's a string from a random MSV70 file:

;$CARB_MODE_9_CVN 1F0CADD1 9

1F0CADD1 is the CRC32 bit checksum for this file. CARB_MODE_9_CVN is probably an OBD2 command that they can request for the DME to report the checksum (they aren't going to read that directly either, the checksum calculation varies a LOT by different cars). And earlier cars can't respond to CARB_MODE_9_CVN because it didn't exist when they were made. So unless they're manually reading the checksum somehow or calculating it manually I don't see how they could do it.

The key here is the DME itself calculates the checksum, and we have full control over the DME. You can effectively make it calculate any value you want, or report any value you want. So the check itself will be bypassed by pretty much all tuners I'm sure.

They also have a CARB_MODE_9_CVN for the program - but not the boot code AFAIK.. Either way, the work around is the same. Force it to a specific value, or have it report the original value regardless.

[nando]

That's not going to work. They going to pug in a computer to the OBD2 port and send a command to retrieve the software identification and checksum, OBD readiness values, errors, etc. So unless you're going to reverse engineer that and duplicate it all exactly, including other parts of OBD2, it's far easier to mathematically force it to match or spoof the correct value straight from the DME.

[Julien]

simple solution: clone check sum value to rahpsberry pie burried under dash into a dummy harness. Suck it california!

A colleague had a similar device that he got caught with before working at the shop where I met him... Needless to say he's a felon now because of that.

[e30strokr]

I figures it would be something simple... now way the manufactures will give the data to the goverment, just clone he file ... im staying OBD1 anyways..

[reelizmpro]

This is targeting 2000+ OBD 2 + cars with custom software to defeat sensors, ie smog pump etc. These tunes and custom ECU's have been widely marketed the last decade. It was only a matter of time before they set their sights on the software.

Going back to the E30 era, Dinan cornered the market in CA because they were CARB certified. They charged $400 a chip and 10-20K for turbo kits that would be rudimentary today. There was Autothority on the East coast and Jim Conforti that would be had for less but they may not pass CA emissions and certainly weren't CARB certified. That was a time when people cared about those things. Then with the internet, many people started sourcing better parts/tunes for less money.

[SOneThreeCoupe]

The worst part is that, no matter what, the enthusiasts don't have the votes necessary to force a change.

I think there would be a case in court that this is government overreach and, frankly, a waste of taxpayer dollars for relatively few offenders caught- CA estimates 8-10 cars per day that will be caught. That's 3,650 cars per year on the high end, some of which may be producing exactly the same emissions as a factory tune in normal driving.

CA needs to focus on the sniffer and the sniffer only. Anything else is immaterial. Stop hunting boogeymen and go after the real problems. We need to be thinking about our emissions, especially in areas that are basins, but this is not based on reality and is a feel-good measure.

[McGyver]

I was under the impression that this was already in effect for ODB-II cars, but I guess not.

Does anyone know how this would effect cars that have been flash tuned? I'd like to get an MHD or BM3 tune for my n55 car. I anticipated needing to flash back to stock and re-locking the ECU prior to smog. Would this checksum fail my car because the ECU has previously been flashed? (I assume this is how BMW detects past tunes when they try to reject warranty claims)

[nando]

I was under the impression that this was already in effect for ODB-II cars, but I guess not.

Does anyone know how this would effect cars that have been flash tuned? I'd like to get an MHD or BM3 tune for my n55 car. I anticipated needing to flash back to stock and re-locking the ECU prior to smog. Would this checksum fail my car because the ECU has previously been flashed? (I assume this is how BMW detects past tunes when they try to reject warranty claims)

Sort of. The manufacturers have reported checksums to CARB since about the year 2000, but it was never enforced before now.

Time for me to finally implement this: https://www.nayuki.io/page/forcing-a...c-to-any-value

[varg]

You probably shouldn't broadcast that you're doing that, or at least obfuscate it. The EPA has been cracking down on performance shops like crazy, I'll bet CARB is even worse. Forcing a checksum is probably just as big of a fine if not worse than removing/tampering with emission equipment

[nando]

Eh. It's like any software that can modify other software - I'm not making files for people in California necessarily (and I don't live there either). But I can make the software to do that and people can use it if they wish, for "off road use only" of course. I don't see how changing the checksum is the same as installing some sort of bypass device either - it doesn't do anything that tries to bypass their check or even avoid detection. it just calculates the checksum in a different way tha always has the same result. if you ripped the file and ran the checksum manually, you'd still get the same result. Unless you're going to make checksum calculations themselves illegal somehow, I don't see what they could do about it.

Also any sort of DME flashing was already technically illegal, like other things that are technically illegal but widespread because the laws are vague and politicians do not understand how any of this stuff actually works. Technically, you can't even flash the DME at all, for any reason. Not because of emissions, but because it requires reverse engineering or bypassing encryption which is also illegal from the standpoint of the DCMA. But the security is hopelessly weak and easy to bypass, and everyone knows how to do it. In some cases you don't even need to break the encryption, because the keys themselves are weak and easy to factor.. but I digress.

You basically can't do anything at all to modify or repair, or even resell anything you own, and must accept what the corporations shove in your face without breaking some sort of law. If that's OK with you, that's fine. I'll leave it at that..