Ok so now that the weather is cooler, the noise is now gone from cold start up? Does the SAI only turn on during start up when the weather is warm? Good that the noise is gone but annoying that I can't bring it in to a tech to replicate the noise.

 

The SAI should run even in cold weather, make that especially in cold weather. I can always tell when the fall driving season is upon the land as the posts asking about some kind of fan running when I start my car in the morning start appearing on the forums.

Generally, the car is noisier in colder weather, too, not counting the contribution the SAI makes, so I'm at a loss to explain why you no longer hear the noise at a cold start. One WAG is the pump is no longer working but I would expect the CEL to be on because of this.

Or the noise could have been coming from some other source. Maybe an AOS? A split or crack in a hose or bellows or even in the diaphragm inside the unit? With the colder temperature this has resulted in the AOS hose or bellows or even the diaphragm in the unit becoming less pliable and the split or crack is no longer allowing air flow?

Admittedly a long shot. Not impossible mind you but a long shot.

 

Macster I really appreciate the help. What's WAG? Is that the water pump? I guess the only thing for me to do is wait until the weather warms up and see if the whistle appears again. It won't do be any good to bring it in since I can't replicate the sound anymore.

 

WAG? Sorry, I thought you knew. Short for wild assed guess.

 

SAI system is very finicky, maybe because it doesn't do much. May of had some light corrosion build up while inactive causeing the squeal when 1st operating & gradually went away thru operation. It will probably return next autumn.