Chirping noise from catalytic converter

Max M · October 24, 2019

So I’ve been having this issue and seems progressively worse, I took the truck into the dealership and they were telling me the chirping noise I’m having is the Passive exhaust valve however I have the AFM disabled. And the truck still makes the noise with the PEV clamped open. When I was pulling into my driveway while the truck was idling it was even making the noise and it’s nowhere close to where the PEV is. Wondering if it’s my catalytic converters failing? Has anyone else seen the same issue?

CamGTP · October 24, 2019

Sounds more like two pieces of metal rubbing/vibrating together.

Check your heat shields and that clamp on the back of the y-pipe there. When the vehicle is cool you can smack the exhaust with a rubber mallet to check for noise and it makes it easier to wiggle/shackle stuff to see where the noise is coming from.

HeySkippyDog · October 25, 2019

+1 for mallet testing.

On my 1st Chevy many years ago, I changed the muffler to a single in-dual out Super 44 and changed my rattling catalytic converter to a hi-flow.

In doing those changes, the vibration from the deep tone of the exhaust was just right to make my exhaust shield by the transmission ring. I found it by tapping my exhaust along its length with a rubber mallet until I heard a ring.

I bent the heat shield away from the starter/transmission ever so slightly and the ringing stopped.

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Max M · October 25, 2019

Well, after mallet testing I found what I believe the issue was the clamp holding the exhaust to the catalytic converter as seen in the vid. That clamp was loose to the point where it could spin around. I tightened it up and tested the truck driving around and noise seemed to be gone. Will update if the issue comes up again. It’s ridiculous how my problem couldn’t be identified by the stealership but instead on this forum. Thanks for the suggestions! Saved me some massive headaches.