Quote:
Originally Posted by pikkagtr
If it was about cleaner air , they should ONLY care about what comes out the tail pipe
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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.
Quote:
Originally Posted by jv004
Any recent Smog check experiences people has had with pure turbo and tune installed since this dumb unnecessary thing was enacted?
I've been planning to get PS2 and I'm now ready to upgrade but now I'm not too sure....  |
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.