My 95 Z28 just failed smog and I am talking really failed. The plugs and wires and fuel filter were done less than a year ago and then I just changed the oil and the airfilter and filled it with 91 and got it hot before I brought it in. So any ideas?

 

The biggest part of passing smog is going to be your cat. Other components that contribute to emissions stuff are the EGR system as well as the A.I.R. system. Make sure your O2 sensors are giving good data so your mixture is right. Other than that there's not a lot I can think of, my biggest bet would be on the cat...

 

My friend also said it would be the cat but I noticed the ones from Kragen and autozone say "except california" and the only place I could find one is Napa auto parts but that says only for before 95 so does that mean I have to buy a more expensive one?

 

It really doesn't matter too much what you get for your cat, either way you're going to have to get it welded in. I'd go to your local muffler/exhaust shop and see if they have any recomendations. You need at least a GM large size cat, keep that in mind.

 

magnaflow high flo cat ftw

 

I already got someone to weld it I just want to make sure I get the right one. I trust his welding job just not sure if he is going to pick out the right cat.

 

Ok so I am new to this whole emission smog crap so I started doing a little research and I have found on other forums that the cats usually affect the NOx which I didnt have a problem with. I only failed in HC and CO. Plugs and wires were done june 07 along with the fuel filter. One thing I do notice is my AIR pump hose is missing the clamp and is disconnected but I dont see how the smog guy missed that. Im probably just going to end up taking it to a shop but I just dont trust people to work on my car.

 

HC and CO are the result of too much unburnt fuel in the exhaust (rich mix, misfire, etc) or a bad cat. The AIR pump only works a few minutes when the engine is first started to get the cat to light up fast. Being that your AIR pump was partially disconnected, there is a good chance that the cat got fouled and no longer doing its job. If you do get a new cat, make sure it is a 3 way type.

 

im not in california so idk if you guys can help me but i DONT have a cat but plan on getting a magnaflow high flow cat. Do i just get the straight up round cat or do i get the one with the air tube for my 94? Can i just weld the cat in and pass or do i have to hook my computer up to it aswell?

 

The 94s didn't not come with air tubes, the shape makes no difference as long as it fits, and the OBDI computer on your car couldn't care less whether there is a cat or not.