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Catalytic Converter suggestions..


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A roadblock kinda day - failed smog on my 1977 280z.

Bad catalytic converter (no numbers on it), and high CO%.

Short story is it passed fine two years ago, and now it doesn't.

Per this thread i'll drive around for 30min on 87 gas before testing. But i'll still need a cat!

A couple of parameters:

1) it has to be a california approved cat

2) it's gotta mate to the MSA 3-2 header system (might as well replace that while i have someone replace the cat).

any suggestions? What have you guys had good / bad experiences with? what's the price you paid?

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My Accord needs a new catalytic as well and Rockauto seems to have good prices. For your car, both options are under $200. Before calling the converter dead, make sure your car is in a good state of tune (i.e. not running overly rich). A highway drive prior to the test is obligatory to light off the cat.

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I think his CAT is bad because it doesn't have any production dates or manufacture date codes on it which according to CA is NOT legal without them. I know, what a crock! This started in early 2010. I went through it in 2010 with 77 280. Bought a CAT from Motorsport and went to my shop to have them install it and they said they couldn't because it was not 50 state legal. Got Motorsport on the phone and they didn't even know about the new "rule". But gave me a refund though.

Justin, you need to call a local shop (muffler, exhaust) and tell them you need a Cat for your Z. It should cost you around $250 installed. Dont change out your header. They installed my CAT back a little and I have a Motorsport header. I use Pronto brake and muffler where I live and they do a good job. Where are you located. Im in Ventura. As far as CO's go, what were they? Did you fail by a lot? I have learned, to smog one of these in CA you need to thoroughly tune them up first and take it to them hot. Good luck.

Edited by rcb280z
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Thanks Leon and rcb!

Yeah, one of the first things i did was break out the AFM adjustment manual just to see if that can do it, since higher CO levels correlate to fuel richness. But even if i adjust the mix, my cat is crap anyways so i'll have to change it out (California...sometimes...man!).

CO levels are as follows:


15mph 1.36 0.17 2.03

25mph 1.16 0.15 2.66

so not too bad out of range. my guess is that a new cat will fix that CO level.

Thanks for the suggestions too rcb, i called local shops, and you're right, it'll between $200 - $275.

"Don't change out your header" - really? oh no! can't use the MSA exhaust header and muffler for some perf / auditory goodness?

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This wouldn't help a cat issue but back in the old days when I lived in Californy I used "Guaranteed to Pass" a can of which was put in the tank before a smog test. Various cars had that stuff put in the tank and they always passed though I didn't always know how bad they were to begin with.

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