teeter

I failed my emissions test a few weeks ago. So I brought my Civic to my mechanic and he said that chances are I'll need a new O2 sensor and possibly a new cat. He hasn't run any tests on the car yet to verify this, but after looking over the charts, that's his initial diagnosis. So, I think now would be the perfect time to supplant the old cat with a free flowing one. After getting an opinion or two from friends, a little birdie told me not to get one unless I had forced induction.
What's your take? If it matters, I do have a cat-back system already.

Sorry for being ignorant, I'm still learning
Pearl

Spade

Free flowing cats take longer to heat up.....can effect emissions, how is your gas milage? If it isn't that good you do need an O2 sensor, and you probably need the cat......IF you get the free flowing cat, let your car run for about a hour or two to get that sucker nice and hot and then when you go to the SMOG station, leave it running until they pull it up onto the dyno themselves. That way your cat will be nice and warmed up when they test. Unfortunatly the O2 is going to be about 100-160 but, if you have an older car it is a good envestment fuel milage and performance wise.


THE ONLY STUPID QUESTION IS THE ONE NOT ASKED.


[Modified by Spade, 6:48 PM 9/7/2001]

teeter

Thanks Spade.

I do alot of highway driving to/from work and usually get anywhere from 36-44 mpg. How much a difference in performance would I be looking at?

I always thought that free-flow cats were prominent in muscle cars rather than imports. Is that true?

Spade

Your milage seems good, I learned the hard way about not doing the O2 sensor, replaced the cat and then smogged and still failed. Just do the O2 to save yourself the trouble...it will need to be replaced eventually.

Free flows are more prominent on muscles cause more of them are made specifically for them since they have been around/modified for a longer time. The free flow will help out by about 1-2 Hp but, if you plan at any time in the future adding power, it will help out to have a free flow. I have also noticed that free flows are almost the same as stock or OE's. Just make sure you aren't getting a racing cat....they are not street legal they are racing legal as some racing series require that you use a cat.