I am trying to figure out if the 3rd module is a cat. converter or a resonator on the '03 V8. I know there are two cats coming down from the headers then under the passenger side of the truck is another thing that to me looks like a resonator not a cat. The reason I ask is others on T4R.org have cut it out and put a custom y-pipe to reduce the restriction there. I wanted to what others had to say about it. I would like to remove it if possible because there seems to be a lot of restriction there based on how the pipes are welded together. Any info is appreciated. Thanks

 

Brian,

Yep, that 3rd "module" is indeed an additional catalytic converter. In the early 3rd Gens that had the sulfur smell issue, Toyota replaced that catalytic converter to get rid of the smell. Since removing it would undoubtedly mess with your emissions, I would caution against removing that converter.

However, If I'm not mistaken (it's been a while since I looked at my exhaust system), the y-pipe should actually be a removable piece of the exhaust system. Each header should have a connection to the y-pipe, and the single exhaust pipe going to the 3rd converter should also have a connection to it. Therefore, you should be able to simply unbolt the y-pipe and replace it without messing with the converters.

HTH.

Steve

 

Thanks Steve, I am gonna look into what I can do...thanks for the info, I appreciate it. There just seems to be so much restriction there, it looks like they squashed the pipes together where they enter the 3rd cat. I will have to look into having a custom piece made that I can be bolted in and out from the stock flanges.

 

Yup, that is definitely a CAT. When I had the Sulfur TSB done, they replaced that with a brand new unit. I guess running 3 CATs allows the 4Runner to be classified under LEV (Low Emissions Vehicle).

 

My '03 4.0 V6 has 4 cats...