Catco 3" and smog... yes another Q.

[Blues13]

Ok, done some searchin, but didn't find any answers on this..

I'm in cali and I'm trying to pass the sniffer test on my Sr20det..let's say I already passed the visuals. I have a 90' 240sx with blacktop sr and 3" exhaust/dp running @ 10psi.

Problem is: When I took it on the dyno sniffer with the stock cat that came with the car, I failed on the HC levels - max was 121, measured was 135.. so the tech told me to just get a new cat and that should fix it..

So, I come back with a brand new Catco 3" cat, and my car fails again, but this time the HC levels increased to 156 and the NO levels skyrocket so my NO levels fails as well (968max/1390meas @ 15mph and 895max/2145meas @ 25) it was 352 @ 15 and 830 @ 25 using the stock cat. The CO levels with the new 3" cat is better though.

My question is, what the freak is going on,... why is the brand new cat doing worse? And what can I do to fix it? I already changed my 02 sensor and drove the car 30 min prior to the test..

[gijoe69]

My friend also had a problem like that but this is what he did he bought this fuel additive from Kragen called Guarenteed to Pass Smog..its in the fuel additive aisle at kragen should be like 10 bucks...b4 you re-do the sniffer have an empty tank and add the guarennted to pass smog additive and get the highest octane 91octane or 92 then re-smog it, you should pass now.....but how the hell did you pass visual? lol

[Blues13]

Yeah poured that "guaranteed to pass smog.." junk a tank before the 1st test with the stock cat.. guess it doesn't apply to my engine.. :rolleyes:

Heh, as for the visual.. lets jus say he was a cool guy.

[holisticbeatz]

Originally posted by Blues13
lets jus say he was a cool guy.


If he's a cool guy, why don't you slip him a $100 bill and let him run another S13 in your place.

[gijoe69]

Hey! thats not legal! haha fuq the bullshyt laws! haha Illegal all the way!!! watcha know about that haha

[gijoe69]

or you can try removing the downpipe and putting the stock downpipe back on and have stock downpipe, cat on

[cdlong]

the cat doesn't do anything for hydrocarbons. you might have a problem with the EGR, there are other things that cause it, but i forget. the reason the new cat does worse is because it's a high performance cat, it's meant to flow better, not minimize emissions. that it doesn't pass that part of smog now is suprising. you may need to use a regular car for the test.

[Evil S14]

im glad indiana doesnt have emissions, id fail like a mofo

no cat
no egr valve
and we have 94 octane pump gas!:boink:

[Blues13]

Ok, he was cool.. but not that cool. He didn't own the shop, so he can't pull too many strings.

Anyways, I understand it's a high performance cat.. but if it doesn't pass smog, what's the point of having a cat at all? It's crap if it can't pass smog. The suprising part is that the brand new cat performs a lot worse than a 5-10 yr old cat.

Yea, I'm sure the EGR sensor/valve has something to do with it since mine's welded shut.. not sure exactly what it does, but its for emissions and I don't think the sr's have it. So how are all these SRs passing sniffers?

About the DP - how would that help emissions at all?

[misnomer]

Do cats have a "break in" period? Make certain you get your car warmed up before taking it in.

[autobahNESSA]

y dont you get a pipe welded up with both cats on it so you can pass? or get the original welded to the old down pipe, and bolt the catco where the cat usually goes. you should pass then.
hey do you attend any of the 240 meets? I noticed ur in sf.

[Blues13]

I don't know about break-in periods for the cat.. anyone have any experience on this? I did Drive the car around for about half an hour before the test. The cat however was put on the day before so don't know if that would make a difference.

Hmm.. two cats on a pipe.. yea, I'm sure it'll help a bit, but not crazy about going through all that only to fail again. I'm going to try to do a tune up on my car I guess before the next smog.. maybe even retard the timing.. heard that helps.. dunno. I've been to only about one 240 meet so far, pretty new to the SF area.. I'm going to try to be there saturday @ union city though.