6 replies to this topic

[WilsonSteele]

Everyone,

    This is mostly for the California crowd, but maybe others have been through it as well.

 

    Also for the "street-legal, I kept a plate on it crowd".  I find it very useful to be able to drive the car to the dyno when I want, or drive it to work a few times during the week before racing just to practice shifting.

 

    Last time I has to pass smog check in CA to get my lic. plate sticker, I was at the edge of NOx and COx emissions.

 

    Since then, I bought a new head, checked compression which is over 185 on all 4, bought the 5X Racing adjustable FPR from Weekend-Racer, and tuned on the dyno to get my AFR to just about 12:1.  Starts at 15:1, ends at 12.16:1, pretty linear decrease from 3500 to 6700 RPM.

 

    Every time I go to the emissions dyno, I swap out the open SD exhaust for the stock cat and muffler set up.  For those elsewhere, in California, they put you on a dyno and run up to 3000 RPM at full and part throttle to test emissions.

 

    SOOOooooo, who wants to venture a guess whether I've made my emissions better or worse?  From chemistry, I think that running hte engine leaner will produce better flame front progression, more complete mixture consumption, and fewer COx by products.  BUT, higher EGTs mean more chances for NOx waste, which isn't as well catalizied by the cat.

 

  As always, I love to over think it.  And I will post results after my smog test.  But with the restrictor plate, AFR tuned to the plate, more or less smae ambient conditions as the dyno day, and the complete list of stock emissions control bits, has the AFR made my greenhouse impact better or worse, in the eyes of Big Brother Bear?  (That neutered animal on the Calif. Flag....)

 

    Thanks for your thoughts,

        Wilson

 

[Kyle Freiheit]

If the cat is in good condition, just go for a long drive before you test. Get the cat nice and warm, you should be fine. Your AFRs aren't that far from stock. 

 

Kyle

[Alberto]

I was unable to pass after the AFM was adjusted.  Had to swap in an unmodified one.  YMMV

[Jim Boemler]

Your numbers will probably be just fine. Mine were always squeaky clean, checked 4-5 times.

[Pickles Miata]

Let me start by saying that I am new to this and am not a chemist but I believe if follow my advice you should be fine.

 

1) Leave all your go fast goodies attached.

 

2)  Fill the tank to capacity.  Make sure it is running out the fill nozzle.

 

3) Find your nearby West to East Interstate.  ( i.e.. I 20, I 40.  Please note direction is Important)

 

4)  Floor that puppy till you run out of gas.  Refill and repeat until you are far from that godforsaken state.

     Once you run out of gas in a climate that you would enjoy, call this place home.  

 

5)  Send for your family.  (This step is completely optional.)

 

6)  Save the extra money that you would have paid to the government  thieves in  California and retire a few years earlier.

     Also, Removing yourself from that Nanny State will enrich your quality of life and perhaps allow you to live longer furthering your    enjoyment of your saved money and allowing you to race cars far beyond the years that you should.

 

Sorry about the thread hijack so early but it had to be said.

 

P.S.  If you are from a government agency this was all a joke.  I love and respect every thing that you guys do and I get excited when I get the privilege of sending you 30% of my money.  It's like Christmas every time I write that check.  Thanks again big brother.  

Sincerely,

Carlos Danger

[RazerX]

Ok, I live in CA and actually drive my car to the track.  

 

However two years ago, after resetting my timing, swapping the exhaust back to stock, it fail to pass smog, by a few NOx just at idle.  So I retarded the timing to edge under the law and went first thing in the morning when it was cool.   Heat = NOx.  I passed by 1 NOx.  Two years ago I had a stock AFM and no APR but now I do.  I think this year, I may try some additives...     

 

BTW, most don't know this but the actual omission levels are not fixed in CA, so your omission limits actually go down.  This means it is harder and harder to have older cars pass even if they are running well.  It is by design to get older cars off the road.

[SaulSpeedwell]

My vote:  Higher NOx on the full throttle test where the car will now run leaner in open loop mode, no significant effect on the cruise test if we assume the car is staying closed loop (but this depends entirely on how much throttle and load corresponds with the People's Republic of California's definition of "part throttle").

 

Pre-2001 Miatas kick into open loop (wherein they start marching ever-richer as RPMs climb) pretty easily, but at anything resembling "steady cruise" below ~5K RPM, the AFR should be dominated by the 02.

 

If you want to keep overthinking it, which I encourage:),  think about the cams being retarded from the decking that was done to increase the CR