XS NO on smog check
11-25-2009, 09:25 AM
#1
Thread Starter
XS NO on smog check
I have a low compression Laskey block and reworked head with oversized valves.
Went to the smog check Monday and passed everything except oxides of nitrogen (NO.)
It pushed out 850 ppm at 15 mph and 880 at 25mph with a limit of 451 and 738 respectively.
Changed the cat and retarded the intake cam 2 degrees. Got to love those Toda cam gears.
Recheck it blew 80 ppm at 15 mph and 2 ppm at 25mph. From 880 to 2. 
The tech went crazy trying to find out how it was done. "I don't know, left it at the dealers and they took care of it."
He spent 30 minutes more going over it trying to see something. He did notice a loose header bolt. Thank you.
Changing the cat and Intake cam timing can certainly make a huge difference in NO emissions.
Went to the smog check Monday and passed everything except oxides of nitrogen (NO.)
It pushed out 850 ppm at 15 mph and 880 at 25mph with a limit of 451 and 738 respectively.
Changed the cat and retarded the intake cam 2 degrees. Got to love those Toda cam gears.
Recheck it blew 80 ppm at 15 mph and 2 ppm at 25mph. From 880 to 2. The tech went crazy trying to find out how it was done. "I don't know, left it at the dealers and they took care of it."
He spent 30 minutes more going over it trying to see something. He did notice a loose header bolt. Thank you.Changing the cat and Intake cam timing can certainly make a huge difference in NO emissions.
11-25-2009, 09:43 AM
#2
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http://en.wikipedia.org/wiki/Catalytic_converter
The cat is supposed to deal with the nitrogen oxides.
Put that old cat back but don't change the timing of the cams to see which made the difference
Why did you decide to change the timing of the cams?
Did you change it back timing again or did you leave it?
The cat is supposed to deal with the nitrogen oxides.
Put that old cat back but don't change the timing of the cams to see which made the difference
Why did you decide to change the timing of the cams?
Did you change it back timing again or did you leave it?
11-25-2009, 10:38 AM
#5
Thread Starter
Originally Posted by SpitfireS,Nov 25 2009, 11:43 AM
http://en.wikipedia.org/wiki/Catalytic_converter
The cat is supposed to deal with the nitrogen oxides.
Put that old cat back but don't change the timing of the cams to see which made the difference
Why did you decide to change the timing of the cams?
Did you change it back timing again or did you leave it?
The cat is supposed to deal with the nitrogen oxides.
Put that old cat back but don't change the timing of the cams to see which made the difference
Why did you decide to change the timing of the cams?
Did you change it back timing again or did you leave it?
The cat may have been responsible but I was using a low mileage cat before.
Went from a 10,000 mile cat to a 2,000 mile cat. My tuner thought it was more the cat than the timing.
I still can not get over it going down to 2.
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