I just put a K&N filter and rice pipe intake on my SSEi a few days ago, and coming home from work the other night, I noticed a strange clicking / tapping sound coming from the engine bay. I'm not sure if it has been there since i put the intake on, but I am almost positive that it hasn't. It sounds almost like valves clicking on a cold day, fairly quiet but definately audible from inside the cabin. It gets louder is I approach boost, but then is hard to hear becuaes of the whine. This morning on the way to work I didn't hear it until I was about two miles away, so that almost makes me suspect that occurs at higher engine bay temps. Also, the intake is not cold-air yet, heat shield has not been built yet. Any advice as to what it might be or how to find out and fix it? The temp sensor in the filter is from a 97 and I did do kind of a shotty job at splicing the wire together, but I'm going to redo it today.

That is your evap canister purge solonoid, and is more obvious in cold weather.

Disconnect the electrical connector next time it does it. It'll stop. Just as confirmation. This is normal operation and has freaked out alot of members here in the past.

I agree with Willwren. If the noise is being caused by the fuel evap solenoid, it'* a high-speed clicking noise that doesn't change with engine RPMs...the noise sounds kinda like a high-speed version of the noise you'll hear when you shake a PCV valve back and forth to hear if it'* moving freely.

this sound does increase with engine rpms however...
i'll take a better hear of it on my way to grab something for lunch.
i don't think it does it all the time.

Ever hear of the clacking, ticking noise coming from the front, which was only evident when the car was moving, not the engine RPM? Come to find out, it was a radiator fan blade hitting something when the air was going through it. What make and model this dilemma was on, I don't remember. Just an idea.