i have a new to me 03 trailblazer. i have driven about 200 miles on it since i bought it. i am noticing a rattling sound underneath the truck. it seems to only make the noise when i am idling or when stopped. also, the idle is a tiny bit rough it almost feels like it could stall but doesn't. just wondering if anyone has any ideas or more experiences like these.

 

i looked into it a little more. i turned the car on and looked underneath to see if something was loose or whatever. i couldn't identify anything like that. it sounds like the sound is coming more from the passenger's side; basically under the passenger's seat. it almost sounds like the exhaust pipe. but the exhaust is tight and not hitting anything. when i drive the rattle is not there. the car runs fine just wondering what the rattle is. any help or ideas would be appreciated

 

i had a similar issue, ended up being the catalytic converter. The honeycomb inside ended up breaking off and rattling around. Be sure to check your cat.

 

i checked again this time paying attention to the cat. it seems like that may be the culprit. i can't be certain but it seems like a logical conclusion. i guess the only way to fix it is to replace the cat? the shield is not loose.

i live in NJ and the only thing they check in inspection anymore is exhaust so, i want to make sure i will not affect my emissions down the road when i am up for inspection again. i guess it comes to is a bolt-on as good as a weld-on. i would rather do it myself so the bolt-on option would have to be done since i don't have access to a welder. but i guess i could get the cat online and have somebody weld it on for me for relatively cheap.

i saw this. i just don't want to get the wrong thing. also i don't want to have to buy a pricey oem replacement part if i don't have to. has anyone else replaced their cat? maybe in NJ and passed inspection?

 

sorry. that was a cat for a trailblazer. i have just a blazer. so this one

 

Well while trying to figure out what to do about the rattle. I'm still pretty sure that is the cat. Anyway, as i'm doing errands I get in my car and on comes the service engine soon light. I went to autozone and got code P0455 and P0306. So, the cat drops to 3rd on my list now.

 

Ok just to put a bow on this thread. I got really lucky today. After getting those codes I figured I might as well check the gas cap since it looks like a vacuum problem. It wasnt even screwed in. Guy at the gas station didn't put it in right. Tightened it up and drove it. Check engine light went off:-) Now back to the cat. Just wanted to share my experience in case it helps anyone else.

 

I am currently experiencing the same rattling you describe. So I went ahead and measured my original cat and i am getting an overall length of 14". I am on the fence about which cat to purchase because I have heard that certain "high flow" cats throw up the SES LIGHT. Please let me know if you end up buying and installing the eastern catalytic converter and if you have any SES light afterwards. So far, your find of the Eastern Catalytic Converter is the most afforadable converter I have seen. I would definitely purchase one if all goes well.

 

I am also still on the fence about which cat to buy. I like the price of he eastern but, I dont want it to go bad because it is just poor quality. Hoping someone who knows will chime in.