JohnnyEF

I have failed smog on the 25mph Nox section of the testing. My car is a stock 93 civic hb cx. The car was about 125 over the limit for the noxs I believe. So I was told by the smog ref to get a new cat, and that should take care of the problem. I have have a random technology cat sitting at my house with about 2,000 miles on it. I know the random cat is high flowing, but will the cat due when it comes down to smog? Or should I buy a cat a the local muffler shop? Just trying to save some cash. Since my car is a cx, I believe the cat is connected to the downpipe. The smog shop told me to get the cat installed in the back of the car because it would be cheaper? Will my nox be effected because the cat is in the rear? And the smog tech guy told me to just leave my stock cat on, because that would cost to much money to replace. Any opinions will be appreciated on this issue. The car only has 89,000 miles on it, and I just changed the O2 sensor with a stock NGK one. The car was driven hard before the testing so the cat would be hot. I just thought since the car was stock it would have no problem with smog, I guess I was wrong.
I live in california also if that makes any difference. Everything else passed on the test but the nox's part. The timing was good and the sparkplugs too. The idle is a little shaking, but nothing major. I had my car tested with and without a octane booster. TIA

JohnnyEF

ttt

Ricey McRicerton

You could either get a header for a d series motor if your planning on swapping to a D16y8 or something similar and use the new cat with that, or you could have the cat installed after your cat you have now. Either would work, but some tuning could also solve your emissions problem

JohnnyEF

What kind of tuning did you have in mind? Its basically stock and runs good. I can't think of anything other than replacing the cat and cleaning the throttle body and intake manifold. Also I was thinking of cleaning the fuel injection system with some type of fuel additive. Thanks for your reply

JohnnyEF

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