DMPesso

Wats up CL I have an 01 GS430 with 95k and when im idling in park and rev the gas as I let go of the gas you hear a rattling noise from the cat. I had a few exuast leaks that I got repaired which I though would fix that problem but it's something different. The muffler guy I know said "it's inside the cat and can't be fixed and is uneccesary to fix because it's just something loose inside the cat." he said it wont do any harm except for that annoying noise when revving at idle which i can care less about because it doesn't happen when driving thank god. So the question I have for you guys is, is he telling the truth? because I thought a rattling cat meant a bad cat which would cause poor performance and gas mileage. Could this have been caused by an accident from the previous owner?(even though he swears no accidents). Any opinions on what this can be is appreciated thanks

Ant2gs3

replace the cat

oslouie

That's a genius answer.

DMPesso

I was looking for answers besides that. What am I gonna get besides no noise by changing the super expensive cat? Will I notice anything else. The car seems like it drives fine.

GS4_Fiend

iTrader: (22)

replace the cat

Mike813

iTrader: (5)

its the heat shield protecting the cat and the rest of the pipe.

its a common problem, just go under there and cut it off with tin snips or unbolt it if you can still loosen the bolts.

some examples from IS/GS owners

https://www.clublexus.com/forums/is-...tling-fix.html

https://www.clublexus.com/forums/gs-...converter.html

https://www.clublexus.com/forums/gs-...eatshield.html

starfyrels

iTrader: (2)

Youre in ny, so you need a cat converter to pass emissions. With a failed baffle inside your cat conv you are essentially rocking a straight pipe. You will not pass emissions the next time you have to renew. The catalyst within the converter is gone for you.

Search ebay or junk yards/craigslist for some.

In worst case your engine could "choke" as the cat could become blocked and limit exhaust flow out of your muffler.

DMPesso

Well it can't be the heat shield because when I got the exaust leaks repaired they removed the heat shield because we thought that was the issue but it seems to be coming internally from the cat. But funny you say that I just passed inspecton yesterday with the cat like that and i do not have a check engine light on. Is it possible that something is loose inside the cat but that the cat is still good because the car seems to be running fine

DMPesso

And as I said before it ONLY makes noise when im parked and I press the gas. As I let go of the gas you hear a rattling coming from inside the cat. When I'm driving I dont notice anything

swat1727

iTrader: (2)

it's sounds like the Cat is broken inside. i say take it to a muffler shop and they will be able to tell you for sure.

L3XOTIC

Car-part.com

You will find a cat for cheap.

2gs4u8

THAT SOLVES UR ANSWer!

Acidic

iTrader: (1)

With a dog and call it a day...

nezlyfe

If you didn't have the heat shields removed I def would've said that's your issue, was for me, but try replacing headers completely one of he members can pass the inspection (Jeff) and he had his car boosted......or take the headers off and shake it until the loose part comes out lol

Mike813

iTrader: (5)

did they remove all of the shields? (under cat, over cat on frame, shield on the pipe) theres one over and under the cat. most of the links i provided was the lower shield thats exposed to our ny weathers but there are times the upper shield might get hit by road debris and bend inwards slightly leaning on the cat causing it to rattle a bit as well. im just trying to give you the cheapest alternative before buying a new cat but if you believe theres something inside take it to a exhaust shop and see if they can shake whatevers inside out? has to be something heavy for it to even make a rattling sound.

personally i would go and remove all the shield below from the Y pipe back to the midpipe and check it again to see if the sound continues.