So on some cold starts I get this annoying @ss rattle from under the car, so yesterday I heard it again so I got under the car and put pressure on the cats and it stopped! and then I put pressure on the y pipe and it stopped again. so do you guys think it's a heat shield? any of you had the same issue? I got 112k miles on my 2003z if that helps. I'm thinking about taking off the cats and y pipe and taking their shields off and heat wrapping them or put small exhaust wrap "washers" between the heat sheild bolts. thanks for any positive feedback. I've searched and haven't really found anything specific to my problem. thanks

P.S. the rattle gets worse when the A/C is on when the engine is WARM, but NOT when the engine is COLD. HELP! I'm thinking a certain rpm makes the heat shields rattle. Pita

chris

 

I had a similiar problem. I just ignored it as long as I could . . . until one day I was able to put the car up in the air while it was happening.....and I found it. It was a loose bolt that held one of the exhaust pipe hangers.
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You just have to keep looking.
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awesome man! I'll see if this is what it is, did you just retorque it down?

 

I will be looking under the car today to see if I can find this rattle, I think it may just be a loose bolt as mentioned, I will keep this thread updated with my findings.

 

so I looked under the car and did the tap on everything test, and the only this that makes a somewhat similar noise is the underbody heat shields over the resonator. but doesn't make sense because last time I heard the rattle I was able to push up on the y pipe and the rattle stopped. I believe any upward pressure on the exhaust ( towards the middle of the car ) would make the rattle disappear. ugh. help guys!! I noticed it more pronounced around 9-1100 rpm idle or when the AC is on at idle.

 

Rattle found! the bolt holding the passenger cat brace was broke and free rattling against the cat. hope this helps any of you with the same rattle. im happy