I was kind of bored and a slightly sober last night. Spent some time at the California BAR website downloading the emissions-testing standards for all of the Miatas from 1990 through 2007, and compiling them into chart form. These are the pass/fail thresholds for the standard three-gas tailpipe test to which cars in CA are subjected. 5015 is the 15 MPH at 11.4 to 11.8 HPtest, 2025 is the 25 MPH at 9.5 to 10.1 HP test.








I find the data quite interesting. Apart from the bizarre dips around 94-95, I'd always heard that the reason we have no CARB-legal turbo options later than 99 is that the emissions standards changed drastically around 2000 / 2001. Now, I understand that a proper CARB EO test is far more rigorous than a standard smog check, but I'd have expected there to be some kind of radical change in the testing standards around that point. To the contrary, most of the cutting was done either in the 1.6 era or around the time of the OBD-II transition.

Interesting stuff. Definitely pays to own a '90.

Source of data: Vehicle Test History

 

Looks like they traded off CO and NOx for reduced HC around the time of OBDII.

 

I would not pass CA emissions.

 

How does a high limit become a low limit? My poor attempt at humor.

 

Wow. You're practically dumping raw fuel out the tailpipe, and yet your NOx is also over the limit. How'd you manage to pull off that combo?


Could you explain the joke to me?

 

Now you got me curious, so I dug up my last report:



The car is 23 years old, and yet it passes the 2007 standards with ease, and yet I am STILL considered to be a "High Emitter Profile" for some reason, meaning I get directed every single time.

 

At the beginning of the NOx graph the 5015 test is dirtier than the 2525, then in 93 they crossed over so the 5015 is cleaner than the 2525, that's all I was joking about.

 

Ah. I thought perhaps the low-resolution image of the homosexual superimposed over the graph was of some relevance.

 

i didn't tune for emissions and i have a 200cell cat.

 

but something should have gone down somewhere.