Hey all... I'm posting this up for a buddy of mine. I've already got a decent idea of what the problem is... just wanted to see if anyone had any other ideas.

He's got a rattle in his stock exhaust. We first heard it when he let out on the clutch to back out of the driveway yesterday evening. When the clutch starts to catch you get a slight vibration through the car (filled motor/tranny mounts) and the exhaust rattles right as the car starts to move. It did it again shifting to 2nd as well.

When we got back to the house we sat in the driveway and free revved it for a second or two... up to about 5 grand... not much noise then. But then he held the gas down and kept the RPMs at about 3k for a little while and you could hear it... sounded like something metal fluttering inside the pipes as the exhaust gasses blew past it.

I'm thinking it's his cat. Pieces of it are probably blown out and rattling inside the exhaust. Unfortunately he dosen't have a boost gauge (Ion RL) so I can't tell if he is overboosting any or not... but his custom tune does run on the rich side.

Anyone else wanna throw a conjecture in here? Opinions?

Thanks.

 

the cat maybe?

 

I was sure my rattle was in the exhaust , turns out my rearview mirror was loose. I had a few others listen to it and they agreeded with me so i was getting ready to take it in before i noticed that the rear view's torx screw was backing it's self out . FWIW , Rukkee

 

hey raine, I told photo about this as well. Mine does the same thing at exactly the same point. Kinda sounds like a tightened spring releasing.

I haven't put the gutted cat on mine yet to see if that solves the problem, but when my wife had her QC it did the same thing. Ended up being the baffling in the muffler, which they replaced and fixed the noise.

If he can deal with it for a little while (week or so) I should have the downpipe on mine this weekend. (fingers crossed for wideband to go in as well)

 

Heheh... I believe he'll have to live with it there Jason... with his ticket to pay and needing tires that eats into mod money real fast.

I just don't want his cat to be clogged up and causing him to overboost the engine. Honestly when I heard it it almost sounded like the rattle was coming from up front near where the cat is... though with it echoing in the exhaust system it's kinda hard to be exactly sure.

 

HAHA I hear ya. He has enough already that he has to get before hand.

If he can hold out a couple of weeks, I can get him my cat, which should be good and see if that fixs anything.

 

Mine does the same thing in second I just thought thats the way it sounded cause it did the same thing on my 05 also

 

yea most dealerships will say its nothing, but the salesguy heard it in my wifes and told the service dept it was the exhaust and to replace it.

I just haven't taken mine in because I don't want a stock exhaust.

 

If they are gonna replace it anyways... see if you can pay the difference between the stocker and the GMPP exhaust... it's only like a $50 difference.

 

good point. I noticed that the sound was not there this morning. May have to drive it around some to see if I can get the noise back and bring it into them and see what can be done.

Didn't think of that. Thanks Raine for the thought.

 

My car is in the shop right now for the same thing. I was getting a rattling and my exhaust sounded really strange. They just told me it was because the cat was failing apart on the inside

 

yeah, mine was rattling like that as well. i took it in and it was fine when i left but before i got home it was rattling again. so i finally put it up on a hoist myself and figured out the problem. if you look, the heat shields for the exhaust run through a channel in the unibody. well it is just rivited on in several places. you will also notice it is all metal to metal. what i want to do is get some gromets and put between or some cushion tape and insulate the shield from the body. but what i did in the meantime was just simply bend out the shield so that it wasnt able to vibrate up against the unibody tunnel. easy as pie and problem solved.