How do i know if my cats are clogged? I have a 1990 non-turbo with 1 high flow cat. There is no split air pipe running to the cat (I don't even see a place where it would attach) and as far as i can tell my header covers the little port air valves under the exhaust port. Everything i have read says the cats will get clogged without air but the car runs fine and i don't see how they could possibly be getting any more air than what comes out of the engine. I want to remove my airpump but have read that you can't do that with cats. I'm confused because i can't see any possible way that my airpump is providing extra air to the cat?

pull of you cat and take look

^Yeah, that's how to tell if it's clogged.



It sounds like you have an aftermarket cat that is designed to run w/o fresh air. I would certainly think that the mfr. of the cat would have plumbed a pipe into it if it needed it.



You don't need the airpump for that, but I think it runs the 6th ports on the S5s. Never had a 2nd gen N/A. All my exp. is turbo.



That hole near the exhaust you mentioned is for the EGR I think.



What are the symptoms of the problem you are having?