catalytic converter help

[drboudreaux]

I have a 1997 Subaru Legacy 2.2L. Both cats are rattling and the check engine light is on - it has also failed emissions. I have been told differing things - and I am wondering what folks on this board think. Some people have told me that I can cut out the pre-cat and the cat and replace them with one big cat, hooking up both the upstream and the downstream O2 sensors into the new big cat. Others have said that I cannot legally do this. Is this legal? Secondly, will having one cat screw up the emissions such that it will throw off the downstream O2 sensor and cause the check engine light to stay on, thus continuing to fail emissions? Any help or advice would be appreciated. Also any websites that offer inexpensive replacement cats and sensors would also be valuable. Thanks in advance.

[deiscient]

I have a 1997 Subaru Legacy 2.2L. Both cats are rattling and the check engine light is on - it has also failed emissions. I have been told differing things - and I am wondering what folks on this board think. Some people have told me that I can cut out the pre-cat and the cat and replace them with one big cat, hooking up both the upstream and the downstream O2 sensors into the new big cat. Others have said that I cannot legally do this. Is this legal? Secondly, will having one cat screw up the emissions such that it will throw off the downstream O2 sensor and cause the check engine light to stay on, thus continuing to fail emissions? Any help or advice would be appreciated. Also any websites that offer inexpensive replacement cats and sensors would also be valuable. Thanks in advance.

You may want to check the local clean air/smog laws in your locality. In California you must, repeat, must use OEM-specced exhaust parts exclusively. I see you are "international" so check your state/provincial bureauc..er, laws as well as federal/EU/national. At any rate I would guess that a converter arrangement other than as manufactured would skew the exhaust gas mixtures and yield some funky ECU behavior.

 

Perhaps someone with more ECU experience could comment on whether the engine could "learn" the new output or if some hacking might be required to be compatible.

[lmdew]

I have a stock dual cat from a car I parted out. No problems from the car it came out of. The car was a 96 2.2 Legacy 120K. $100+shipping. Lmdew@hotmail.com

[drboudreaux]

thanks for the offer. unfortunately, I have been busy at work and have not checked the board until today (Friday night) at 1230am. I had it fixed this morning. I put two dynaflow cats on it, $375 installed. Not a bad deal at all. If anyone is in the Houston area, ABC Muffler on N. Shepaer and 43rd street treats you right. Thanks for the help, too. Now, I just have to get the P0325 taken care of and I should be good to go.