Speeddoc

Good afternoon. Does anybody have experience with CA smog testing recently?
I just got my car (2021 C63S AMG Coupe), and don't need to smog for 8 years. But I'm still hoping to find out an answer to the following question:
Can CA smog testing detect a change in the smog "count" that our ECU's apparently do by themselves?. And assuming that is something that CA smog can/does look for, then can the smog test subsequently detect a "count" abnormality if I tune my car with a straightforward OBD2 software tune, and make no other modifications to the car?

Acta_Non_Verba

Short answer is YES. As of July 19, 2021, CA now electronically views and validates a CVN number as part of the emissions test process. This CVN must match the manufacturer's original CVN, or if the mfgr revises the ECU data and revises the CVN, the state will look for that new number. If your ECU is tuned, the intervention changes this CVN and CA will flag it and fail the test.

https://autos.yahoo.com/californias-...183900978.html

Here is an example of a guy, on another forum, that recently failed the test:



There are a couple of POSSIBLE exceptions, although, so far, it appears CA databases are a "little behind" in correct info:

1. If the tune(er) you are using is CARB certified, CA MIGHT have its CARB CVN (but only in theory).
2. Jury is out, but a piggyback might not change the CVN, so if you unplug it before the test, you MIGHT be OK.

A little additional information - if you're going to do a big tune, one that might support cat deletes, then testing time will be rough for you. A modified tune that will support cat deletes will, without a doubt, change the CVN, but come testing time, you will not be able to reload the stock tune w/o replacing the deleted cats. This would not only be caught in visual inspection but you'd have a CEL on running the stock tune w/o cats.

It pays to really think through mods now. Not just what/how you want to mod, but what/how much to reverse what you've done to test, or to sell someday. Dealers are now inspecting tradeins in many places and will not take a car with mods such as cat deletes and ECU mods.

diesel_dan

I've been looking for threads like this and this is the 1st one I've found. So many folks with my M278 or the AMG M157 are running tuned, I really thought this issue (which is just CA for NOW) isn't being discussed more. I had heard that there was a "flash counter" that could be checked as well to determine if you had been flashing tunes in and out. So I asked my MB dealer asst service manager about if MB could determine if a tune had ever been loaded, but I was talking M278/M157 at the time - he said no, they couldn't. More recently I reached out to the tuner I bought my flash tuning from, they are MBW sponsors, btw. Their response was that there is No flash counter for the area in the MCU the tunes are written to, there is however a counter if the entire MCU is reprogrammed. The suggestion they gave was to return the car to stock tune and give it plenty of drive cycles before smog and it will be fine...

Acta_Non_Verba

A couple of comments since I've tuned for several years since 2009.

The dealer has less information than the tuner does. That's BC the dealer does not have access to the tune files. They are kept at a "surface" level in the ECU and if there is a rev from the factory, the factory packages it and only allows the dealer to download the rev. Tune files (and all the data tables) are akin to intellectual property for the manufacturers. Although they're all accomplishing the same thing in an engine management system, they go about it differently. I've seen this first hand as I've accessed these data tables from different manufacturers.

The tuners are all using, in the proper definition, "hack software" to obtain access, they go where the dealer techs are not allowed.

I am making this comment BC "counters" that would ID SW revs are not at the surface level the dealers see, so it would make sense if the dealer cannot see it, they conclude a counter does not exist, but they do. ALL manufacturers know the status of their original SW in the engine management system, if for nothing else, warranties. If someone blows a tuned engine then tries to warranty that engine the first thing the factory asks the dealer for is access to that car's ECU.

Acta_Non_Verba

I knew I had an article saved on tis...took me a while to find it.

California Smog Test Now Includes Checks for Illegal ECM Tuning (motortrend.com)

diesel_dan

Thanks for that article link - much better than the Road & Track article on the same subject. From the quote and text in the article, as long as you return (flash) your vehicle to Stock tune before going in to get Smogged, you'll be fine. Now folks that have gone a lot further than just a flash tune might have more work to do every 2 years...

Acta_Non_Verba

Hi Dan,

You're welcome, any time.

In CA (and other states WILL follow) having the ability to reverse your tune back to stock for an emissions test is wise advice. All hand held tune devices SHOULD store the stock tune it overwrote. The ECU conversions, "ECU mail-ins", etc., not so much.

I think what will be tougher in CA are the supporting mods done to the car to supplement the tune. On my platform (AMG GTx) it is routine to hack off the primary cats and weld in a replacement empty tube (for the life of me I just don't get the primary CAT delete as it offers practically nothing in performance, even with a stage 1 or 2 tune) and intake mods as well. These mods will fail the CA emissions test and reinstalling primary cats on my platform is a major undertaking, so probably not going to do that every two years.

Most other states (AZ where I live) simply hook up a scan tool (part of the state's computer system) if there are any P-codes the emissions test will fail, otherwise, pass as there are no physical inspections. Drive cycles have to be complete too, but as long as there are no emissions codes pending, drive cycles solve themselves with drives.

Best,
Acta

Chamz333

I have an E350 4matic that a service center (not MB) that might have tampered with my idle (scam) basically it became low that my vehicle shakes is there a way to programm ECU to maybe a tad higher so my idle would be higher maybe around 650 ~ 700 to remove the shaking… check all mounts/ and all possible worn out parts that could contribute to shaking at idle .. and ECU is the last one I haven’t checked…

this shop adjusted my on dash TPMS to read 60 psi and recommend to have the TPMS replaced .. which I declined because I knew it wasn’t defective .. this the reason I have suspicions of them tampering my ECU

I have no codes and recently passed SMOG


thank you in advance