What effect will changing out my high-flow cat to a regular cat have on the engine? Will it cause the air/fuel ratio to change? How much HP can I expect to lose?

Currently I am running the Power FC and I am trying to get through emissions. I have done several things so far to get the emissions down, but I am still a little over. Also the car will ocassionally backfire upon deceleration.

If anyone has any answers that might help me straighten this out it would be greatly appreciated.

Thanks

 

i was under the impression that you can tune the power fc to pass emissions. anyway, the fd will always backfire. it's just something that every fd does. of course putting the reg cat back on will decrease the hp of the car, your restricting the exhaust. but you should be able to tune the a/f ratio to be okay. nick

 

have you researched "how to pass emissions"

There are many things that can make you fail besides a problem with your cat.

*The car needs to be WARM
*run the test w/o boosting
*no accessories on during test
*purge fuel catch tube

there are more possible causes, research before you go through the time and expense of switching back to the main cat. BTW, putting your main cat back on may make you run a little richer - no big deal.

 

also run spankin new spark plugs, make sure the ignition is working correctly etc. Also have a functioning airpump

 

The car can be tuned to pass the sniffer with a mid pipe, Get new plugs ,air filter (clean ) new oil , retune idle range and high speed idle range.also no air pump is needed. the Power FC can do it in Tn.

 

I don't care how you tune the car with the PFC, there should be no way in hell to pass emissions without a cat. If you can pass in Tennessee without a cat, why do they even have emissions laws at all? How could you fail?

I guarantee in a state with real emissions testing, that will never work. Not to mention the VISUAL testing required in California and probably other states.

 

All I know is that Cali is VERY strict on their emissions testing including the visual inspection - I would take care of all the things posted here and try the emissions test again before you start swapping out your cat.