[Supras] emission test standards

[Hacker J]

Wow, NJ lets you off easy compared to CA, your car would not pass here with those numbers!

Thought it would be interesting to compare my emissions with and without the 1st cat. 



Bottom line, removing the 1st cat increased my HC and NO significantly.
My low speed HC is now at 80% and that is a little too close for
comfort. I've seen my HC emissions climb with every dyno test since 1999. If you are marginal, you will want both cats to pass. No
doubt lightoff emissions are horribly worse too, but that is not
tested.


If you have some experience in the emissions biz, you'll know that the hardest problem to fix is slightly elevated HC. If you compute my A/F from those emission numbers your get 14.679 (99.8% of stoich) yet I'm running at 80% of the HC limit. Yuck!


The % of pass limit is shown in brackets



Two cats: 

HC 15mph: 51ppm (48.1%)    25mph: 23ppm (28.4%)

CO 15mph: 0.02 (2.9%)    25mph: 0.01 (1.8%)

NO 15mph: 2ppm (0.3%)    25mph: 2ppm (0.3%)



One cat: 

HC 15mph: 85ppm (80.2%)    25mph: 41ppm (50.6%)

CO 15mph: 0.08 (11.4%)    25mph: 0.02 (3.5%)

NO 15mph: 153ppm (20.1%)    25mph: 50ppm (7.1%)



Still, not too bad for a 17 year old converter.

Jon
90T

----- Original Message ----

Rocky:

    The NJ standards are as follows for cars of '91 vintage:

NOx:  1077 PPM
HC:    144   PPM
CO:    0.81%

    Do you happen to know your standards? 

    Before I tore down my '91 to replace the HG as a preventative 
measure, my results with the stock dual cat system were 103 for HC, 0.27 
for CO, and 1063 for NOx.   The EGR might not have been working 
properly.  But as matters would have it, I found that #1 piston did not 
come up to the deck (down about .110"), so a bent connecting rod was 
evident.  So I have about another 20 hours worth of work to complete a 
freshened JDM installation with a Cometic HG, 550 injectors, Lex AFM, 57 
trim turbo, and as yet undetermined means of leaning out the top end 
under boost and possibly retarding the spark about 7 degrees from 7 to 
15 PSI boost. 

    The truth is I'm getting a little nervous about passing CO and HC 
with the 550 and Lex even with the stock dual cats.  The duty cycle of 
the injectors will be about 20% shorter at idle.  If the injectors are a 
little unbalanced, HC goes up dramatically with even the slightest 
misfire, and CO goes up with one richer cylinder. 

       Bernie








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