CA Smog Fail: unusual readings (IMO)

Philprof · May 13, 2010

---------CO2: ---O2: --HC: --CO:-- NO
15mph:--14.8--- .21---- 4--- .01--- 789
25mpg:--14.7--- .16---- 2--- .01--- 904

Aside from the NO, the rest is well below max and average.

Sensor? Cat?

2000 Limited with 171000, passed 9 mos ago.

93gc40 · May 14, 2010

Upsteam O2 sensor and/or cat. When was last tune-up, I guess just plugs for you. You could try a seaform treatment, before you fix the O2 sensors or Cat, Seafoam cam cause problems with those.

the_weirdo · May 14, 2010

My guess is the cat.

Alex E · May 14, 2010

High NoX Will be a bad CAT or EGR, not sure if a 00 has EGR off the top of my head but I'd have someone graph your post CAT o2 sensor and see if its switching.

Alex E · May 14, 2010

If the post o2 is swtching like the pre o2 then the CAT isn't storing oxygen and needs to be replaced.

joe_peters · May 14, 2010

No EGR post 90 4.0s.

5-90 · May 14, 2010

Philprof said:
---------CO2: ---O2: --HC: --CO:-- NO
15mph:--14.8--- .21---- 4--- .01--- 789
25mpg:--14.7--- .16---- 2--- .01--- 904

Aside from the NO, the rest is well below max and average.

Sensor? Cat?

2000 Limited with 171000, passed 9 mos ago.

Whenever you want a smog diagnosis, please post with actual numbers and pass limits - average readings optional.

And post all numbers.

Not only is having all numbers instructive for narrowing down your failed component or condition, but knowing how far you passed/failed by is terribly instructive as well. As you've posted them above, the numbers are meaningless.

Why are you getting a rested after only nine months? I know they've profiled us into "Gross Polluter" status (the bastards!) but it's still biennial AFAIK...

Saudade · May 15, 2010

Unless it's changed in the pas 2 years, the NO max's are 1020ppm@15mph and 880ppm@25mph.

Was everything fully hot when they ran the test? Did they have a big fan blowing in front?

ehall · May 15, 2010

NOX is a product of high combustion temperatures. You're most likely running lean, and that's most likely because the O2 is telling the computer to thin out the mix

SFW516 · May 16, 2010

Yeah I would say your oxygen numbers are way up there. That says and the fact that you are high on NOX that you are running lean which is making you run hot which is bringing NOX up. Could be your oxygen sensor. But before replacing anything expensive make sure you find out the real problem. Could save you a hassle. I know I made the mistake of getting a cheap after market O2 sensor and it didn't work at all. Had to go and get the part from the dealer I think.

Philprof · May 17, 2010

thanks for the responses. I'll try to get the rest of the numbers posted later today. I'm also going to try the sea foam treatment and I don't remember if it was fully hot when tested. It was probably close, but that may make all the difference.

Philprof · May 22, 2010

joe_peters · May 23, 2010

As the others have said, you are running LEAN and that is raising your NOX. Your HC (fuel) is 1/2 and 1/3 of average passing at 15 and 25 mph.

CA Smog Fail: unusual readings (IMO)

Philprof

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93gc40

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the_weirdo

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Alex E

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Alex E

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joe_peters

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5-90

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Saudade

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ehall

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