I did a search but didn't find any posts on this. How do you use temperature tests to determine if a cat is working (assuming it is not clogged)? I've heard that if it's not air injected cat then it will be hotter at the front than the back because most of the action happens there. I've also heard that on non air injected cats it will be hotter at the back because it gets hotter as it goes through. I've heard that on air injected cats it's hotter at the back than at the front because the oxygen injected in the middle causes much of the burn to happen at the back. That sounds sensible.

Does anyone know for sure?

Thanks,

John.

 

Using a heat gun and monitoring the inlet and outlet temps shoudl tell you. If its working it should be hotter at teh outlet of the cat. Maybe around 500 degrees at the intlet and 800 degrees at the outlet? not sure.