Christopher Rost

Hey guys, my firebird makes this awfully annoying rattling noise and it seems no one can find where its coming from. I was hoping one you could save me, or put me in the right direction with some helpful advice! Here's the story for it!

I guess i'll start from the beginning. I purchased my 99 V6 firebird about a year and half ago with 19,000 miles on it. When I got it the car was pristine (still is) With no major problems at all. Everything on it was bone stock because it was owned by an old lady in Florida. When I got home my dad and I noticed a light vibrating noise coming from under the car around the passenger side. It was right next to the catalytic converter/heat shield, in that general area. It wasn't really noticeable so we looked looked into a little bit, but let it go because you could really hear it. Around 35,000 miles I had dual exhaust put on, which was the flow master 80 series. After that the rattle got progressively worse and finally I brought it in to our exhaust guy, which is a family friend of ours, and his crew and him went banging around and found out the double walled pipe leading to the catalytic converter sounded loose if you hit it hard enough, or it was the catalytic converter. At that point I didn't care about the cost, I was just sick of the rattle and told them to cut off the catalytic converter and see if the honeycomb inside was loose. They cut it off to find that nothing rattled inside it so that means its the pipe, which it was because if you hit it mildly hard you could hear a rattling noise. To fix the problem they blew a hole through that pipe and welded it. While they were at it I had them install a flow master high flow catalytic converter. After that it seemed that the rattle had been toned down a bit, but after a couple months it was back, and worse than ever. After going back to the shop six times and them telling me every time they fixed it, weather it be a lifter was hitting a cross member, or they had a weld broke on a lifter, they said that they had fixed the rattle. But every time I drove home it was still there. Last week I had my car in my buddies the shop replacing the headlight assembly and asked him if we could put it up on his lift with me and the car and let me rev it and see if they could see the rattle anywhere or hear it, and he agreed to it. I was up in the air for about 20 minutes while they searched and searched and they didn't find anything. They told me that with these things it's usually the heat shield but after looking at it while I was revving it they said the shield seems very sturdy, then they said it sounded like it might be coming from the transmission but they held a stethoscope to it and heard no rattle. And that brings me to this point, i'm at a complete loss. I'm out of idea's, so i'm turning to this wonderful forum and hoping someone can work their magic and help me get rid of this dang rattle.

Thanks

P.S. Important thing I forgot to add, the more the car is warmed up the louder and worse the rattle is.

P.P.S. Things done to the car
Car now has 52,000 miles
Serpentine belt replaced at 35,000
Number 2 coil-pack replaced at 20,000
Dual flow master exhaust 80 series
High flow catalytic converter
Firehawk Ram Air Hood
K&N air filter
Free Ram Air Mod

SSickLS1SS

its hard to diagnose a rattle without a video and even then its still hard. if its something with the exhaust why not get some longtube headers and that would eliminate any heat shield problems and give you some decent power

Christopher Rost

I will try and get a video up, im going to take the heat shield off sometime this week, and see what happens then. Headers are expensive lol, but I have been looking into them!