Do "high flow" cats pass emissions or are they just a waste of time?
Do cats with O2 ports give the same readings as sensors farther downstream? Ex.



The reason I'm asking these questions is because I'm in the middle of a LT install and am wondering if it would be worth the effort to splice them into the ORY. If not, I guess I'll bite the bullet and pay the yearly $150+ for the exemption.

 

It also depends on how stringent your state's emissions laws are... But, high-flow cats can definitely pass emissions, but state-dependent...

 

A hi-flo cat will pass emissions as long as everything else is running properly. If your engine is running poorly, any cat would have trouble cleaning the exhaust enough to pass.

If the cat has a port on it, it is often times for an air injection system which helps the cat operate efficiently.

 

i wouldent know... i live in florida.... we dont care about the air here lol (as so it would seem)

 

I have got a question for you guys. My car threw a code for the catalytic converter. Showed that out of the 316 times the pcm ran the test it only passed 26 times. I recently noticed that on the passenger side I felt an unusual amount of hot air bellowing out of that side. I put my hand next to the cat and could just feel the hot air spilling out. What does this mean? I am thinking that I will obviously need to replace the cat but I just want to get your guys opinion on the issue.

 

Sounds like it's getting plugged up. If your mileage has gone down recently that would be an indication too.

 

I have noticed any mileage drop and if there is its not substantial. I had my teacher who has has been working on GM cars for 30 years and he told me i need to replace it.

 

He's probably right, the cat gets pretty hot, but not as much as you're describing.

 

Well it will work out anyways that I replace because I have headers that are waiting to be put on as well. Not sure if I should go oem or not

 

A high flow cat will compliment the headers well.