Stock KA Failed Smog

[imnotmatt1189]

So I have a completely stock KA24DE in my '91 S13. I took it in to get it smogged today and I passed the visual and functional but failed the emissions. I'm completely stock and I have all the emissions stuff in my car. I even have AC if that makes a difference.
I failed the "NO (PPM)" part of the emissions test. @ 15 mph, the max was 799 and my S13 measured 1620. But @ 25 mph, I passed, measuring at 474 with the max being 738.
Does anybody know what could be wrong with my S13 and what I can do to fix it so I can pass smog?

[iLOVEmyS13]

mine had the same exact problem with nox, i'm not totally sure on the smog terms but i would double check with other members or do some research. My car did like 1800 on the nox, i had to get a brand new cat.

Also check if your EGR valve is functioning.

[DreamN]

Clean your EGR and check the hoses for any leaks before buying a CAT.

[importdude]

my friends car went from 1800 NO PPM to 840 just 20 to pass
pm me if u want tips

most likely your cat/egr is giving up


best is to post your MAX/and measured of aLL readings

[imnotmatt1189]

my friends car went from 1800 NO PPM to 840 just 20 to pass
pm me if u want tips

most likely your cat/egr is giving up


best is to post your MAX/and measured of aLL readings

PM'd you.

My readings for the smog test:

%CO2 Measured: 13.8 @ 15mph//14.6 @ 25mph
%02 Measured: 1.9 @ 15mph//0.9 @ 25mph
(What I Measured/MAX)
HC (PPM): @15mph: 78/118; @25mph: 31/93
CO (%): @15mph: 0.03/0.75; @25mph: 0.01/0.63
NO (PPM): @15mph: 1620/799 FAIL; @25mph: 474/738

[redwhale240]

I had problems with both HC and NOx. I had to get a new cat to fix the HC and a new EGR solenoid to fix the NOx. Hope that helps.

[wickedjester]

try egr first!!

[FRpilot]

i'm currently having problem passing smog too. i have really high hc and nox. co seems ok, about 50% of max, but hc and nox is within 10-20 from max. passed but failed visual since cel came on during test.

failed functional test because code 32 came up (egr). seems like egr is working mechanically as i tested vacuum and the egr valve opens when throttle is open, so i changed egr temp sensor to another used but better condition one since people say thats likely the culprit for code 32. this code has no bearing on "turning on" egr on our cars, it's all mechanical through vacuum. code pops up because temp sensor tells ecu if egr is actually working.

next test, light came on again but off during test this time, but smog tech guy was also revving it higher this time and it barely failed emissions this time since it got 804 nox (but hc went down considerably). maybe due to higher revving?

it seems like EGR is functioning and my cat is dying. i don't know why both hc and nox would be so high and some of the searches i've read up on say if its both hc and nox, probably the cat. nox is high, but not too high like 1500+ like others, which tells me egr is probably working.

one of the smog techs also agreed and said the cat is probably dying or very weak, and the egr is barely saving my ass, b/c if it wasn't functioning i wouldn't be just barely passing emissions. so i changed my cat to another used, but better condition cat.

will try smog again tomorrow and will update.

[dennydizzo]

same problem...passed co...barely failed hc.. and my nox was over 3000 and over 1000 at 15mph..cleaned out my egr and bought a new cat now my nox is wayy under limits passed with flying colors... but im pretty sure i wouldve just passed with just a new catalytic the egr was a bitch to get out and clean..

[imnotmatt1189]

so i took my s13 to a shop to get it diagnosed to see what i can do to get it to pass smog... and the guy said the timing was off and that he fixed it and cleaned out the maf sensor... and he said my cat was dying but i should pass the smog test without a new cat but that i would need a new cat in the future. i took my car to the smog test without getting a new cat and got about 600 lower on the NO but still failed. i got a new catalytic converter installed and went in today to try to pass the smog test again... and my numbers were even higher than the 2nd time. WTF???? somebody please help me. my car is running COMPLETELY fine, runs extremely smooth, i even have ac if that matters. I have around 200 on all 4 cylinders and my timing is readjusted to the right timing and i have a new cat. I have no idea what else to do.

[singlecamslam]

If i really must pass smog and have no time to mess around, 20% methanol 80% gas mixture and drive your car hard before smog. Worked for me countless of times, one time i added rubbing alcohol, and it passed.

[miklos]

My egr solenoid had no ground, the vacuum hoses were melted and there was carbon caked inside the manifold. And that carbon was there after running Seafoam through the throttle body. SOHC KA24