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Discussion Starter #1
And... that sucks.

I don't know if this is the right spot for this topic or not.

15 MPH : 94 (max) / 191 (meas)
25 MPH : 76 (max) / 140 (meas)

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Except for the new soft top, new Cobalt ignition wires, an oil change, and a cupholder, she is as she was when I purchased her a few weeks ago.

I was a naive douchebag for simply believing the guy when he said it had a smog check on file.

Southern California by the way. Lancaster, to be more specific.

Bugger.
 

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Discussion Starter #3
Re: I just failed smog.

I'm hesitant to purchase a new cat or a new o2 sensor though, since I'm seeing lots of threads where those parts (and more) were purchased and they still failed. It would be cheaper to go the illegal route, but I don't really want to do that either.

I'm drinking a lot tonight.
 

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Re: I just failed smog.

I'd recommend you see if anyone in the area are willing to loan you good cat for a day to try and pass. Then if you pass and care about the environment (I really dont) go buy a new cat.
 

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SuperMOD
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Re: I just failed smog.

well...what did you fail on, so we can help you diagnose a bit...NOx, HC??

Also, there's a law in CA where you can't sell a car that won't pass smog...I don't know much about it, but you could look into that, it could be the sellers responsibility, especially since he told you it WOULD pass...but idk if it applies to private sales.
 

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Discussion Starter #8
Re: I just failed smog.

Erm...

HC(PPM)
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15MPH : 94 (Max) / 191 (Meas)
25MPH : 76 (Max) / 140 (Meas)


NO (PPM)
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15MPH : 847 (Max) / 1273 (Meas)
25MPH : 786 (Max) / 952 (Meas)


So... I guess I failed both of those. I passed CO.



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I've seen a lot of posts on that law you mentioned Haigog, but I'm not sure how to enforce that sort of thing. It doesn't help that I'm a bit less than intimidating.


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I'll definitely start checking around to start borrowing a cat then, thanks.
 

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Re: I just failed smog.

I failed smog too, I put a full tank of 91 and NOS octane boost, drove it around for 25min, let it idle for 15min, and it still failed. It failed HC. :( Idk what to do, there's someone here that'll let me pass illegally for $100. I'm also with OP about being hesitant on purchasing parts for fear of it failing anyway. There should be a Smog Diagnosis thread where everyone posts their readings.
 

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Re: I just failed smog.

I failed smog too, I put a full tank of 91 and NOS octane boost, drove it around for 25min, let it idle for 15min, and it still failed. It failed HC. :( Idk what to do, there's someone here that'll let me pass illegally for $100. I'm also with OP about being hesitant on purchasing parts for fear of it failing anyway. There should be a Smog Diagnosis thread where everyone posts their readings.
Done....and it's official. Post your emissions info here and lets start a database.
 

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Re: I just failed smog.

Erm...

HC(PPM)
----------
15MPH : 94 (Max) / 191 (Meas)
25MPH : 76 (Max) / 140 (Meas)


NO (PPM)
----------

15MPH : 847 (Max) / 1273 (Meas)
25MPH : 786 (Max) / 952 (Meas)


So... I guess I failed both of those. I passed CO.



===============

I've seen a lot of posts on that law you mentioned Haigog, but I'm not sure how to enforce that sort of thing. It doesn't help that I'm a bit less than intimidating.


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I'll definitely start checking around to start borrowing a cat then, thanks.
HC is unburned gasoline, so your EGR kicks in, which lowers NOx
Your NOx is high and your EGR works, so your catalytic converter is dead.

O2 sensor may produce lean or rich condition if its broken. So at best new O2 sensor may bring HC to spec but NOx will rise.

Good thing you are not that far off the NOx, my audi with new universal cat is 2500ppm on NOx. and with old cat was 3500ppm. I pass cause I drive less that 5K miles/year

I would go illegal route if I could. Way more convenient.
btw, check that you even have a cat in the first place.
 

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SuperMOD
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I'm gonna sayyyyy you're running rich, thereby making your HC go up...
This also would cause your cat to warm up a bit slower, which is why your NO is higher at 15mph than it is at 25...

I'd pull your O2 sensor and at minimum take a look at it...if it looks all nasty, you can get a new one for 20 bucks if you know how to solder, and 50 bucks for plug-n-play action. Then borrow a cat, and reset your ECU by unplugging your battery and I don't see any reason why it shouldn't pass...you're already very close.

JDMX5, 91 + octane booster will also raise HC lol...you may have done yourself wrong there...


*ninja'd by kakarot...however, kakarot made the assumption that he has a later car with EGR, and I made the assumption that he's on an OBD1 car lol...soooo which is it OP?*
 

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The person who sold me the car instructed me to run 91 with NOS octane boost, he claimed that's how he passed smog last time. So I spent $60 total on a full tank of 91 and the octane boost >< So now I can't pass smog even more since I have 91? TTT-TTT The guy who sold me the car is trying to help me pass smog.. but we did a pretest and it failed. Meh, idk what to do..
 

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going from memory here so I hope my info is right, correct me if I am wrong.
Check for unmetered air leak somewhere downstream from AFM, and Upstream from O2 sensor.
High Nox = High temperatures
Extra HC in cat = HOT
Too Lean = High HC
When you run too rich all you get is High CO. Which the OPs CO is fine.
Vacuum leaks affect lower rpm more so than higher rpm.
NOX
15MPH : 847 (Max) / 1273 (Meas)
25MPH : 786 (Max) / 952 (Meas)
Higher nox at rpm = extra gas in cat which is burning hotter and creating more NOX
At higher speeds nox is lower due to having a closer to stoichiometric air to fuel ratio.
EGR lowers NOX by reducing temperatures within the combustion chamber by introducing exhaust gasses. Could also be a clogged egr or egr passages (constriction has to be mechanically removed) I often use a coat hanger then some shop air.

Fun fact. CARB has been cracking down on test only shops that replace Cats to "fix" a smog related issue. Sticking a new cat will usually allow you to "pass" smog.. But the problem will come back, it almost always does. So most test stations dont do that anymore, cus their ass is on the line.
 

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Big Pimpin'
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I'm gonna sayyyyy you're running rich, thereby making your HC go up...
To my knowledge miatas run pig rich anyway. I failed smog the first go around then I went on a nice 15-20 minute drive and passed with flying colors. Both my CO2 and HC numbers were miles below the state benchmark on the second go 'round. I'm sure Oregon has a different standard though
 
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