I passed NV smog check!

[granatl]

I just passed the Nevada smog check. I wanted to share my results, and what things I did that may help others pass too.
Our test is a tailpipe sniffer done at 2500 RPM and idle (anywhere between 450 RPM and 1200 RPM).
2500 test
12 HC (<=220 allowed)
0.22 CO% (<=1.20 allowed)
15.20 CO2
0 O2%

idle test (968 RPM)
96 HC
0.00 CO%
14.40 CO2
2.4 O2%

My car is an 87 GN with ported intake, ported iron heads, roller cam, 6 year old catalytic convertor, a TE-60 and 55# injectors. I have my RJC Power Plate drilled for EGR.
I downloaded the smog chip from GNTTYPE.ORG, and then did my own little tweaks. Since I don't have a previous set of results, I don't know if I made things better or not, so my changes might or might not be any good. They were:
increased fan on to 207, fan off to 200
Set Closed Loop A/F ratio to 15.0:1
I took out ~5 degrees of timing out of the lower RPM's to try and heat the exhaust more (more flame in the exhaust).
I raised the P/N idle curve to 1000 around the relevant temperatures.
I also put 87 octane in the tank.
I changed the oil just minutes before driving over to the test.
My idle BLM was hovering right around 128, and I saw plenty of cross counts.
My exhaust had a hint of sour smell, but was otherwise coming out fairly clean.

Again, I hope someone finds this useful.

 

[gofstbuick]

I'm glad you passed, but I think you may have gotten the emissions too lean (at idle epsecially). If you richen the mixture at idle, the CO2 will rise, the O2 will fall to near zero (just like the 2500rpm readings), CO will rise a little and HC will fall a lot. Since the catalyst uses O2 to complete combustion, there should be no O2 left after it passes from the cat. The O2 is stored past the NOx bed of the cat and is released in the oxidation part of the cat as HC and CO passes into the oxidation bed. The oxidation bed changes HC and CO to CO2 and H2O, hence the O2 should be used up. Since there is still 2.4% O2, it appears you may have driven the idle emissions to the border of lean misfire.

 

[LV GN]

Originally posted by granatl
I just passed the Nevada smog check. I wanted to share my results, and what things I did that may help others pass too.
Our test is a tailpipe sniffer done at 2500 RPM and idle (anywhere between 450 RPM and 1200 RPM).
2500 test
12 HC (<=220 allowed)
0.22 CO% (<=1.20 allowed)
15.20 CO2
0 O2%

idle test (968 RPM)
96 HC
0.00 CO%
14.40 CO2
2.4 O2%

My car is an 87 GN with ported intake, ported iron heads, roller cam, 6 year old catalytic convertor, a TE-60 and 55# injectors. I have my RJC Power Plate drilled for EGR.
I downloaded the smog chip from GNTTYPE.ORG, and then did my own little tweaks. Since I don't have a previous set of results, I don't know if I made things better or not, so my changes might or might not be any good. They were:
increased fan on to 207, fan off to 200
Set Closed Loop A/F ratio to 15.0:1
I took out ~5 degrees of timing out of the lower RPM's to try and heat the exhaust more (more flame in the exhaust).
I raised the P/N idle curve to 1000 around the relevant temperatures.
I also put 87 octane in the tank.
I changed the oil just minutes before driving over to the test.
My idle BLM was hovering right around 128, and I saw plenty of cross counts.
My exhaust had a hint of sour smell, but was otherwise coming out fairly clean.

Again, I hope someone finds this useful.

show off!!

 

[granatl]

Originally posted by gofstbuick
I'm glad you passed, but I think you may have gotten the emissions too lean (at idle epsecially). If you richen the mixture at idle, the CO2 will rise, the O2 will fall to near zero (just like the 2500rpm readings), CO will rise a little and HC will fall a lot. Since the catalyst uses O2 to complete combustion, there should be no O2 left after it passes from the cat. The O2 is stored past the NOx bed of the cat and is released in the oxidation part of the cat as HC and CO passes into the oxidation bed. The oxidation bed changes HC and CO to CO2 and H2O, hence the O2 should be used up. Since there is still 2.4% O2, it appears you may have driven the idle emissions to the border of lean misfire.

Next year, I'll try your suggestions. I still have the smog program loaded today, and driving around, the car is very smooth (may be the 1000 RPM idle though). Since I can't use the turbo, and the car is running "hot", I do immediately notice the MPG improvements.
I have a great article at home about how to improve one item of the smog test, while sacrificing the others. In the past, I seem to think it was always HC's that got me (at idle), so that's why I chose to lean it out a little this year. Maybe I need to try 14.9:1, to keep the HC's down, but then get the improvements that you're suggesting.