Ok guys, so after much thought last night i said let me try one last thing before i take it to lexus.. I decided i will disconnect the exhaust pipe from the header and see if im getting airflow. So i did and it was fine coming out of the header, so decide to test drive and bam! Car runs like a beast!! Loud as hell but now I know its the cat from after the header and now i just need a catback. Im assuming the beating from the previous owner and those plugs and all wore out the cat. Im good to go now, thanks to all who helped me out! I will def be jumping in on other convos....

 

good job, i can recommend the tanabe medallion catback (although it is very quiet)

 

If your cats are shot, a cat-BACK will still require some new cats. I am still getting familiar with my GS4 but if they don't have 'pre-cats' then as long as you get that sorted without throwing O2 sensor codes you'll be golden.

Glad to see my old Sentra's mishap helped out (hopefully that's 1 of your problems solved for sure).

 

Thanks alot!! Yeah i really don't want super loud although i wouldn't mind a little growl in it lol.... And yeah i'm gonna look and see what I can find, it's the lower cat not the ones on the headers but there is one o2 sensor there. Will it run ok if i just delete that o2?

 

It does have pre-cats. Basically 2 cats are up on the headers and those have sensors pre-cat and then there is one more lower cat on the pipe that bolts up to the headers and there is a sensor there also... But it seems fine right now and no code with that whole pipe disconnected...

 

One does not simply delete an O2 sensor.

However, depending on the location of this 3rd O2 sensor (is it in front of the 3rd cat, or is it AFTER the 3rd cat?) you can simply keep it and still be able to remove the 3rd cat, and pass emissions. I recall on my '09 Altima Coupe V6, there were pre-cats with o2 sensor after that, and a 3rd cat right after the 02 sensor, so when I had an aftermarket y-pipe put in, it removed the 3rd cat, but the o2 sensor of course didn't know the diff, resulting in no CEL or other codes whatsoever.

IF your shot 3rd cat (assuming that's what is going on) is before the O2 sensor, then chances are removing it will cause the Engine light to go off. You may be needing a hi-flow or another OEM cat in that case to make sure you pass emissions, and also avoid running rich etc. whatever happens when O2 sensors go bonkers.

 

Hmmmmm, thanks for the info. I've been driving it all day to see if it will throw a code and so far no codes and car still running great. I believe that 3rd sensor is right before the cat, but that was the problem because car is perfect now that i unbolted that pipe. But yeah i was thinking maybe a high flow cat or something like that. But hey, the car is running beautifully so im happy! Lol