I installed Chickens Stage 3 CAI over the winter, as well as cleaned the SC and aftercooler, installed plugs, eliminated the EGR, FTVB and installed an oil seperator. Today I took a quick drive down the road and back. When I pulled into the garage I could hear a high pitched whistle. The truck seamed to run fine. Can't tell if any codes were thrown as I have the service engine light on from the EGR delete. When I shut the engine down, the whistle continued for maybe a second or two after the engine stopped. I checked hoses and bolts without finding anything. Has anyone noticed this after installing the Stage 3 CAI? Just wandering if this could be air sucking through the new tubing or air box with the stage 3.

 

You're building vacuum in your crank case, and when you shut the motor off, you get that noise for 2-3 seconds. I have it too. Reason is, I plugged the driver side hose coming from the valve cover on the end that leads to the intake boot. I also had a Moroso vacuum pump on my Mustang, and it would do the same thing, make a noise (like a low pitched squeal) for 2-3 seconds upon shut down. In the end I wouldn't worry about the noise.

 

I didn't plug the driverside vent, I ran a hose around the rear of the SC and T'd it into the oil seperator then from the clean side of the seperator back to the bottom of the throttle body boot. Unless this isn't good enough and it is pulling a vacume on the block.