BobMax

Just got a replacement Bosal center/rear cat in for my '98 Fed Spec car to try to fix a nagging O2 code issue. This is the one just ahead of the rear pipe. There's an O2 port on it at one end.

I don't have the Max here for a few days, but I don't recall the original system having a pre sensor on the cat and the post-cat one is definitely on the rear pipe.

Am I forgetful, or is this for some other model's options? Does any year/spec have an O2 sensor right on the cat itself?

maxima297

The Bosal exhaust has the o2 sensor hole on the cat because there isn't an intermediate pipe between the cat and the y pipe in the Bosal system. The Tenneco system has the o2 sensor hole on the intermediate pipe. Also note that there are 2 separate numbers for the rear pipe, one is for the Cali spec (hence the post cat o2 hole).

BobMax

Oh yeah, I am familiar with that debacle. Bosal does have a pipe with the O2 hole past the rear cat (Fed spec for my year). But, their catalog is incorrect and they clearly don't understand that various years and setups.

So there's no stock setup with an O2 on the cat?

maximaxi

Yes, my 96 I30 has the o2 sensor on the rear/center cat.

All 95-96 cars, as well as California-spec 99 models, have my configuration, the oxygen sensor on the rear cat

The 97-98, and Federal-spec 99's, have your setup, the o2 sensor on a separate pipe behind the cat but before the resonator.

jholley

iTrader: (13)

Your question has been answered numerous times in various thread. You have to start using the SEARCH tool.

Read post 7 that Dennis made in this recent thread

https://maxima.org/forums/4th-genera...en-sensor.html

The 95-96's have the downstream O2 sensor on the CAT. The 97-99's have it behind the CAT on an intermediate S shaped pipe or an aftermarket extended B-pipe.

BobMax

Sorry, but I googled into this forum using "o2 sensor catalytic converter". That thread didn't show up nor did any that seemed to be on target for my specific question. I guess it depends on the specific search criteria you use. I'm sure just about every question someone could ask has been answered out here somewhere... that doesn't mean it can always be found in a reasonable amount of time.

Thanks.

maxima297

I don't have access to their catalog per se, just the vehicle specific diagrams offered here at Napa. The exhaust diagram for Bosal is the same for years 97 to 99, and the Tenneco diagram is the same for 97 - 99, with different part numbers for 96. You have the 98 which is the same diagram as my 97, so you have the same stock setup. I can send you the diagram pictures if you need them.

asand1

iTrader: (1)

My '96 Fed spec has the O2 mounted in the rear of the cat itself.