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      10-29-2021, 11:38 AM   #55
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Drives: 328xd Wagon, M2 Competition
Join Date: Jun 2018
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Quote:
Originally Posted by McGyv3r View Post
The point of the OBDII system is that the car monitors how the car runs. You fail smog if the car can't/hasn't monitored. You also fail smog if your emissions are outside of the factory specs.

It's so much easier, faster, and safer to check the computer versus putting the car on a dyno with a tailpipe sniffer.


The checksum just adds up all the 1's and 0's in the tune on your ECU. After years of recording the checksum on different cars, CARB has a database of valid checksums for each car.

Changing the tune changes the 1's and 0's, so you'll get a different checksum. Forcing a known-good value is a felony. You cannot pass the checksum using an aftermarket tune. Stock, MPE, Dinan, etc are all certified, so they will have a valid checksum.

They also check to see if your ECU is locked (supposedly preventing tunes). Even on a stock tune, you will fail with an unlocked ECU.

Hardware mods that can be controlled by a stock tune won't cause a checksum failure. But you'll fail the visual if it looks aftermarket without an EO number.
Dinan does not have a matching CVN, so you can't say it's certified. Dinan still requires OBD unlocks and all, because it's 'tampered' data afterall. If they have a CARB number, this may not matter, but in the end, the ecu will fail the CVN checksum.


Also, the ecus can be unlocked and tuned without any traces to CAL ID/ CVN, so it's still not exactly that different. I can unlock these M2C ecus without any trace at all, anywhere.
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-2014 328d Wagon, 8HP. Self-tuned, 270hp/430ft-lbs.
-2019 M2 Competition MT, Alpine White. Self-tuned 560hp
-2016 Mini Cooper S, MT. Many plans.
Others:
-E36 328is. 2000 Z3 Roady. 2003 VW Jetta TDI Manual. Estoril Z3M Coupe.
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