Bad Catalytic Converter?

Hey Im new here and was hoping for some advice on my catalytic converter. 2001 tundra 4.7 4wd. I am getting a rattling during acceleration which i believe is in the exhaust so i removed the the downstream 02 sensor (bank 1 sensor 2) and captured a few images inside the cat. The service card i got with the truck shows "both front cats" just under 60k miles ago, and it was welded onto the factory pipes so its aftermarket.

I did this same test on the other cat thru Bank 2 Sensor 2 and the cat is hollow! No honeycomb, which is why i am getting the P0430 there.

I am not getting a P0420, and my B1S2 reading are relatively stable but......any advise? Is that material buildup around the honeycomb normal, or is it melted, loose and boucing around in there causing the rattle i'm hearing?

Thank you

 

What makes you think it’s hollow? I see the screen mesh that’s supposedly the honeycomb or did you not post that pic?
The white stuff I believe is the fiberglass mat. See video below as an example.
https://youtu.be/bEiWcNrypxw?feature=shared

 

P0430 and p0420 are often due to bad upstream or downstream, or a leak. Rattles are often due to the heat shield around the cat being loose.

I dunno what to tell you about the apparent honeycomb issue, but the cat inefficiency codes I just listed, we’ve had so many people trigger those and replacing the upstream and downstream sensors on that bank with genuine Denso sensors and verifying no leaks resolved it.

 

the pictures i posted were from the driver side cat, bank 1. No codes coming from that side, just the odd rattle during acceleration which seems to change with rmp's.

Since i was getting the P0430 i removed the bank 2 cat first because i was planning on cleaning it overnight in soapy water, but after scoping it on the bench i realized it was empty...no honeycomb. So i put it back together for now, expecting that code to be recurring until i buy a new cat for that side.

nice video! Thank you

 

Do you have the heat shields and are they loose as @shifty` mentioned? That would explain your rattle. I personally found that the small nuts and bolts holding them around the cat rust out and need replacement. At least that’s my experience.

 

I am going to double check the heat shield today, but i believe i saw that the two halves are tack welded together over the cat. The noise changes tone with rpm's and only noticeable during acceleration which is why i suspected the cat may be blocked or loose and rattling around. The previous owner was also driving the truck with cylinder #5 spark plug blown out and misfiring so that cylinder was running rich which i know is bad for the cat. Could i have an imbalance issue since only one cat has the honeycomb and the other is hollow?

I did replace both exhaust manifolds. Thinking i may have an exhaust leak, i applied smoke first at the tailpipe. I found a donut seal between the resonator and muffler needed replacement. Then i applied smoke in the bank 1 sensor 2 bung and no gross leaks detected. No ticking at idle. In fact my acceleration/reving engine at park sounds great. Its not until i put it in drive and accelerate do i hear this noise.

I did experience another noise from the truck during acceleration but i think it was due to overgreasing the slip yolk at the rear differenctial. My hanes manual says to apply grease unil it comes out the seal. I applied many pumps from my grease gun and no grease spit out of the seal. Upon first drive i felt a binding feeling, removed the zerk fitting and a bunch of grease spit out under pressure. The binding went away so i think that is resolved. But i do think i will remove the slip yolk for a thorough clean and regrease in the not to distant future. But since my main noise changes with rpm im thinking it is unrelated to this issue.

Thanks for the help!

 

Does the rattling happen if you accelerate in Neutral or Park? Or only accelerating while rolling?

 

it only rattles/rumbles when rolling

 

Another infamous rattler is that flange bracket which goes over the section where the donut gasket is located between the muffler and resonator. I’ve had a few instances where that would rattle and either had to tighten or replace to keep it from moving.

 

yes! I experienced that also. I used my smoke machine to detect a leak at that joint. I replaced the seal and tightened that clamp. About a week later that clamp loosened, rotated down and was rattling. Tightened back up and am still getting a very minor leak from that spot. Is that clamp still available? Dealership item? Thanks!

 

I would hope so. I bought one a couple year ago from the dealership myself and haven’t put it on yet.

 

You can only tighten that clamp until the inner tab bottoms out and thats it. Mine still leaks after cleaning the mating surfaces thoroughly and using the factory gasket....but i know this minor leak isnt causing my main issue