So I smogged and failed recently at the test only, and became a gross polluter...

My numbers weren't too bad. HC was fine which is great! I believe the cats are relatively new, definitely not original. Passed fine last time with them.

This time the only problem was CO levels. I read around a bit and folks were saying that higher CO levels could be due to rich mixture. When I did the test I hadn't cleaned the K&N filter, and it was pretty dirty. Since then I changed the filter and oil. Plugs, wire, and rotor and cap are relatively new. I don't want to throw a bunch of cash in because, I think I'm gonna sell her after the smog. Also changed a hose the guy said needed replacing. Also timing was off so I reset timing and reset the idle speed which was at 1k, which is also a fail.

So do you guys think the CO fail was due to the dirty filter and oil? Is that usually the reason for higher CO%?

input appreciated.

 

the attached pic doesn't cover every scenario, but high CO and low NOX with low HC's = rich, so maybe its an oxygen sensor?

bad air injection (acv, etc) usually ends up with high HC's, and a bad cat would have high hc's as well (i'd think)

 

Oh good point, thanks for the info. I agree I think since my HCs are low, the cat is operating fine and the acv seems good, i took it apart, cleaned it and checked it out cause I know it can cause issues. My idle was a little off as well but I reset idle and checked tps adjustment and it seems good at 800rpms.

I forgot to mention that I did replace the oxygen sensor as well...

they're only like $20 so i figured I should do that as well. The old one looked pretty damn beat... so hopefully the tune up does the job.

I thought about doing the alcohol gallon in the tank but, would rather do it right than just cheat.

 

If you replaced the o2 sensor after your test, you probably will pass. I'd take it back for another test and if it fails, THEN put methanol in the tank

fm

 

maybe there is an air leak, and the cat isn't geeting enough air?

or find someone that will pass any car for $100

 

Got her all ready to go, went down to the smog place round the corner from my house to retest and they weren't open yet so I'll go in a bit.

Should be good, thanks for the advice

 

$100 lol.

a normal smog at some places is already $70.

 

Haha here in stockton its 200 $ to "pass" at most places...150 $ if u find the right guy. If the o2 sensor is now new you probably won't have any issues passing...although in my experience with 3 different fbs...cats usually burn out between 6 months and a year due to our exhaust heat...the pre cats are normally ok but the main cat takes one hell of a beating...especially if you push the car like it wants XD

In my 82 the exhaust pipes kept getting hot as hell and cracking so I had to do a whole new setup...went thick wall with that and still burnt cats like crazy even all stock and running well..my 85 kept burning through the exhaust flange gaskets so I had them all welded up and again burned through cats like crazy....both cars were stock 12a cars....

From your results though I agree it was probably the o2 sensor..

 

something is wrong with it if its melting things....

 

hahah.... yah and if it's on fire, then it's probably needs some tuning.

 

Yeah probably had a lot wrong with both cars but I still managed to get them to pass every time...and they idled smooth as hell and not super rich so I dunno why they ran so hot...

 

Maybe they were too lean? Feels good to drive lean but can be hot...

 

Its possible...ca weather and humidity can make carb tuning difficult...and constant...

 

DIdn't have too much issues with my 12a, though I did have a nice holley carb that was a bit much at low rpm but great waaaaay up high

fun stuff, just jetting is a pain

 

So I went to smog yesterday, Passed with no issues

markedly better numbers. Guess it was nothing major but I'm sure the o2 sensor mustve had a lot to do with it. The low HC numbers signaled that the cat was in good order, which makes my life easier.