I recently installed a CAI on my '97 RS and I have been hearing a funny vibrating sound when I start the car. It doesn't sound exactly solid, more like something hollow (My guess is the tubing from the filter to the MAF). However; I can't seem to find out where it's coming from. The rattling sound goes away after driving for a bit, or when the engine warms up. Has anyone else had this issue?

EDIT: Forgot to mention that the CAI is a 3" aluminum tubing with couplers at the MAF and at the halfway point of the tubes, and the filter is under the engine compartment above the splash guard. Picture for reference:

 

With that type of open intake, it makes it a lot easier to hear the TB sucking air. And it may sound a little weird with a cold engine when it's running richer, then mellows out after the engine warms up. Is that maybe what you're hearing?

 

TBH, I was thinking the same thing. I just wanted a second (Or third, or fourth, etc...) opinion. Is there any way to eliminate that sound that you know of? My car sounds like absolute poopy when I first start it up, and I want to try to mitigate that as much as possible.

One question, however: If it is indeed the TB sucking in air, why does the sound eventually die down after running for a while instead of being a constant?

 

I've had that same thing before, and presently with my Jeep Cherokee with a CAI. The intake sounds a little crackly when the engine is cold. Seems to be a characteristic of what sound it makes when the engine is running rich (cold). Which is why the sound would go away after the engine heats up (leans out). The stock air cleaner box has a muffling effect on the intake. Does it bother you that much? Then put the old setup back on.

 

Darth Vader NO! - YouTube

 

with the cai you can hear the air going through the aic valve better, once warmed up the iac closes some to bring the idle down. that may be why the noise is less when warm. it does look like the tube is against the body, that would cause a rattle. maybe try wraping with some tape to see if that stops it.

 

Or door edge moulding on that one side would do the trick!

 

 

Not sure what you mean by the smiley there? Do you know what I'm referring to?

 

I know what you mean by the moulding, but not a damn clue why you said it