Over the past couple days, I've noticed a very metallic sound coming from my car. It is definitely coming from the front end, and seems to be on the passengers side. It will go away for periods of time, and then all of the sudden just come back. It defintely doesn't sound like it is coming from inside the engine. I have also noticed a slight drop in power, and a fairly significant drop in gas mileage (3-4 mpg). Could my cat be going bad? I'm not throwing a code, but it seems like the most logical explanation to me.

Thanks,
Frank

 

Sometimes the heat sheild on the catalytic converter will pop its welds off and start to rattle. Get under there and toy with it to see if it moves around. You can either paperclip it shut if you dont have a welder, or just do what I did and rip it off.

 

it can be a broken substrate inside the cat too. that ultimately can travel down to the muffler.

 

Loose Heat Shield on Cat.......Look for the simple solution first.

 

I would put my money on either a bad heat shield or a defective cat. Those heat shields are fastened to the body with very small screws that fall victim to rust pretty easily. When I did my headers, most of the heads were snapped off.