The California smog check goes by 15 Mph and 25 Mph tests to determine the levels of smog.
What if second gear was swapped out in favor of lower RPMs to help pass?
Would it be possible if someone could find the sweet spot on their engine, then swap out the gear to pass.

I have a BARD car, so im not looking to cheat anything. Having a debate with a friend.

 

Its all the chud dude get sum seafoam and that will clean yur chud!

 

Its not the speed that gets you. Its the load. Its higher on the ASM15/50 to test the NOX emissions generated from climbing a hill and lower on the ASM25/25 to simulate highway driving HC/CO.

There is also a minimum RPM the vehicle must be at to test. If its too much different it also sets a red flag in the system(but that's more of an issue for the tech). Its a lot more in depth than everyone thinks.

 

Changing the gear ratio will not affect the emission results any more than a different tire size. The test is designed with an accptable RPM range at MPH and I doubt that a slight difference will change the results enough to matter.