Its not the motor itself, its the exhaust. Like when you first start out in gear i get this rattling sound. I have a feeling when the motor turns a little, it throws the I-pipe up against the floorpan or frame somewhere, and it makes this chitter sound. It does it in first and in reverse, sometimes it'll do it if it shifts hard into second. Does anyone else's car do this? And if yours has done it, or did do it how did you fix it, or do you know for sure where its tapping the floorpan?

Its a 96 3.8.

I do have dual exhaust on it, but it was doing this before back when it had the regular single factory exhaust, so i believe its the I-pipe..

 

It could be the I pipe vibrating up against that support brace that goes across it near the cat. I just got a pair of pliers and bent the support brace down on each side. No more vibrating.

 

i'll look into that, thanks.

I'm also wondering if it could be the x-brace, i dont' know how close the pipe comes to it. (its a convertible, so it has the x-brace). I wish there was a way i could see where its vibrating, but since it only does it when the car is moving, its kinda hard to look up under the passenger side, LoL...

 

Do I?!!

I've got TWO, at the moment. A light rattle coming from the heatshield and another (louder) coming further towards the front because of a loose clamp.


Its my 3rd or 4th rattle, including when the antenna was loose. My car must be special.


I did get a sig out of it, though.

 

BTW, mine is idle and very low RPMs (around 1600 or so). Last time I had it, it would rattle much further up the rpm band. Makes it seem like I"m driving a beater


Temporary fix: Tighten everything up.

Permanent fix: Trade it in for a Mustang

 

My car is curently making the same noise, last time this happened it was the cat falling apart. I put on a new one and it was fine. Mine is getting progressivly worse. It strated being only when i first gave it gas in 1st or reverse, and now it just makes its's randomly. So I'm assuming its the cat again.

 

in other words the best solution for me, is when i go to get the stupid muffler place that put my exhaust on crooked to get them to bend one of the pipes to make it straight, i should get them to deal with it. It did it before the exhaust was changed over to dual, but not as much, it has gotten progressivly more noticible.

 

ha i just started having same prob....looks like its a heat shield near rear of car by muffler...i bent tip of it down and it stopped for a week...bottomed out and started again...gonna have to fix again i guess

 

Me too, course it didn't start happening until after i cut the cats off. After i cut the cats off and went to a muffler shop and had them weld a piece of pipe where the cat was, and my duals also. There was no rattling for a while, but now there is a rattling sound all the time. Its starts after the car warms up, exhaust wise, and sounds like i'm driving a clunker. I've talked to some ppl about it but they all say it is a brace or something loose. i've been under the car and can't find anything loose when it's cold. The only think i can think off is that when the exhaust heats up it expandes and started touching something. This happens in all gears and at almost all rpm ranges. If anyone has any ideas lemme know, thanx, AJ

 

I crawled all up under the car yesterday, and i everywhere the pipes are a good 2 to 3 inches away from everything.. so i can't figure out what it could be touching. right in the middle of the car, there is a heat shield that touches the pipe, but it looks like its attached to the pipe.. and its like way up under there where you can't reach from the side of the car.. I'll go take some pictures of it in a minute, and then edit this post..

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Edit:

I took some pictures, but they all came out really dark, except for the one of the muffler, but i know thats now the problem..



Oh! you can see the heatshield i was talking about in that pictures.. its all the way at the edge going back toward the motor.

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my problem is that heatshield for the gas tank by the muffler...if i bend the corner down it seems to fix it....it kinda vibrates with my exhuast for some reason...its real strange...and it only happens at low RPMS....

 

i have a 96 3.8 liter 5-speed and i had that same prob. the rattle was almost beating a hole in the bottom of my center console. i got under the car and my transmission bracket was off on one side and i put another screw in it and it stopped my prob totally.

 

not anything to do with tranny on me...ive had bad tranny mount and thats completely different sound...this one is coming from the vibrating heatshield for some reason...mehh...soon as it stops raining ill have to fix it somehow

 

I think i'm just going to lie to the muffler shop. Since i have to take it up there to have them heat up the drivers side outlet on my dual exhaust and bend it so that its straight (because they put it on crooked) i'm going to say that it never rattled before they put my new exhaust on.. And make them track it down and fix it..

 

Yep, me too. I think it's a resonant frequency thing. I can do a quick fix (bend) but it slowly comes back.