Emissions Miracle

Joined
Oct 1, 2006
Messages
3,995
Location
Sandia Park, NM
After a 3-week scare, I managed to get the 60 to pass emissions again. I tested it 3 weeks ago and failed due to high CO at idle. The limit is 1.20% and I had 1.21%. All the other numbers were within the specifications for passing.

I was worried about how things would turn out after two major repairs to the induction and smog systems since my last test. About a year and a half ago I replaced the manifold and other related gaskets due to deterioration of the old one and massive vacuum leaks preventing the truck from idling. Several of you also recall my air pump failure and replacement during the Colorado trip last summer.

I turned the idle mixture screw in half a turn, bumped the idle-speed back up to about 900 because it dropped when I adjusted the mixture and finally cleaned the K&N air filter. My idle HC ppm went from 25 to 14 and my CO went from 1.21 to 0.01. Logically, my O2 increased from nothing to a surplus of about 2% as well - but there's no specified level for that to pass or fail. I am a little confused because my CO at high speed (~2,500 rpm) went up with the second test. The HC stayed the same (8 ppm) but CO at speed went from 0.01 to 0.67% I didn't think adjusting the idle mixture screw would have any effect on the high speed numbers.
 
Joined
Jul 20, 2003
Messages
1,846
I didn't think adjusting the idle mixture screw would have any effect on the high speed numbers.

Probably didn't. There are a number of parameters that will influence the high RPM stuff: ambient air temp or humidity, how well warmed up the CAT was, mood of the cruiser gods, etc...
 
Joined
Oct 1, 2006
Messages
3,995
Location
Sandia Park, NM
I was thinking it was Gremlins so Cruiser Gods will work too. I'm sure ambient air, humidity, temp of the CAT were all different. I had to sit in line with the engine idling for about 20 minutes on the retest where the first test was just a couple minutes of idling. I'll just not worry about it and be grateful I get two more years until I have to worry about it again.
 

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