I've searched but can't find anything regarding these sounds..... First, when I start up my car sounds meeeaaaan. With a growl and it makes me proud. Then only a couple seconds (15-30) the car goes real silent and runs that way for the rest of the time. When I get up in the high RPM's it has a hint of that original growl but its not quite as mean. Whats the deal with that? The second sound is the other one I spoke of, but I'm not quite sure what it is. It's a buzz or very fast and high pitched rattle that lasts for a blip or 3 seconds. There is no rhyme or reason for when it happens. I tried running the car for a while then letting it idle and checked the cat temps with one of those laser things and the right cat, which is where I think the sound is coming from, is actually cooler than the left! (460 vs 510). I'm not positive its the cat, and will perform the tube listening test soon. Any ideas on that one? Thanks again guys in advance
The first noise is the exhaust air injection system doing its thing. It only engages when the coolant is below a certain temperature (such as on cold starts). This noise should be most noticeable if you listen down the air intake tubes behind the rear quarter windows. It is not an indication of a problem of any kind. The second noise could be several things. On my own 348, I had two small problems that caused symptoms like this. First, I had a broken bracket on the left side of the muffler (a right-angle bracket spot welded onto the side of the muffler). I fixed this by fabricating a new bracket and clamping it onto the pipe. The second problem was a loose "matrix" inside the catalytic converter. I fixed this one by drilling and tapping a screw into the body of the converter, which holds the matrix in position and keeps it from rattling. Others may have other suggestions.
I have read on here some where that they run an air pump for the first 30 seconds or so after start up, this might be what you are hearing? Some of the tech guys will no doubt drop by and offer advice. Edit: one of the tech guys beat me to posting, damn slow internet.
Here's a detailed thread that discusses your noise #1. It's perfectly normal. http://www.ferrarichat.com/forum/showthread.php?t=187143 - Eric
My air injection system was terrible-sounding... lots of rattling. I verified that was the noise by the fact it immediately stopped when disconnecting the vacuum line to each side. Both sides rattled. I have removed the system from both sides and will be plugging the head ports when I finish the major I'm doing (which is going pretty slow). Not sure if Drew has this rattling noise.. but it's very un-Ferrari-like.
