Catalytic converter question

[Korben15]

Ok, my one of my catalytic converters went bad. Do you guys have any replacement you recommend getting? I'll just replace them both at the same time. Also, I've already had my exhaust replaced and the shop used O2 simulators. It's fine to use these again with the new converters, right? Thanks.

[cruzad3r]

ebay - look for a seller "best design" they have a set for 310 or one for 155. the description said the part will fit m35 but it will also fit the X version. I just put one in and no CEL. can't comment on the quality as it's only about a month since i've used it. Be very careful buying used OEM sets as I have to ship it back to the seller due to a busted CAT and these things are HEAVY!!!

[Korben15]

Alright. The dealership told me I needed to replace my cats because the airflow wasn't right to the oxygen sensors. I take it that it will be ok with these cats? Are they basically stock replacements?

[steve_c]

I am a bit confused with the scenario the OP has described.

If you are equipped with CATS, why would you install O2 simulators?
I thought the purpose of the simulators was to provide a fixed exhaust gas feedback to OBDII
in applications where you removed the CATS from the system.
I always believed removing O2 sensors & installing simulators in place could damage the CATS
because the ECM is now getting a fixed signal and not a true variable response to O2 flow out the CATS.

If you are going to install new CATS, why wouldn't you install new O2 sensors in lieu of the simulators in place now?

[Sstupid]

The simulators are for post-cat readings and do not affect the feedback to the fueling system. The post-cat sensors only tell you whether or not the cat is functioning correctly.

[Korben15]

The simulators are for post-cat readings and do not affect the feedback to the fueling system. The post-cat sensors only tell you whether or not the cat is functioning correctly.

The simulators are for the rear O2 sensors, I have no clue why the shop put them in, I didn't ask them to. Also, the oil is still its regular color. *shrug*

[steve_c]

The simulators are for post-cat readings and do not affect the feedback to the fueling system. The post-cat sensors only tell you whether or not the cat is functioning correctly.

ahh-haa, Thanks Sstupid!
I knew I was missing something, I was thinking pre-cat (primary) sensors were swapped for simulators, not the secondary!

Since I do not do any mod work & strictly am a stock emissions guy, (In NY emission testing is tough), It is evident that I do not understand
why you would use post cat simulators while equipped with cats!

[steve_c]

The simulators are for post-cat readings and do not affect the feedback to the fueling system. The post-cat sensors only tell you whether or not the cat is functioning correctly.

The simulators are for the rear O2 sensors, I have no clue why the shop put them in, I didn't ask them to. Also, the oil is still its regular color. *shrug*

Korben,
I too have no clue why you would put simulators in on the secondary side while still leaving cats in place. I do not see the benefit of doing so.
Sstupid is correct about the function of the post cat sensors, but I still do not understand why you would do it as your shop did!