When I turn off my 97 F150 I hear a motorized
noise from the engine for about 30 seconds.

Any one know what that is?

 

I could swear this was just posted ? Well , anyway it's your EGR Vacuum Regulator. Right after shut down while the noise is apparent - put you hand on the EVR - you'll feel it vibrating. It's totally normal and isn't hurting anything.

It's round on top with a little hole in the middle and right next to the TPS sensor in this pic. -



Also , if you can't feel it vibrating, you can unplug the green line from the EGR valve while the EVR is sounding off, it will quit making the noise right away. Just do that to confirm that's where the noise is coming from. - Then plug the EVR to EGR Green Vac line back in.

 

Thanks,

I thought I posted it yesterday also.
But when I looked it seemed to be gone.

 

LOL - you did!! - If you click on your user name, a drop down appears - find all posts by corvetteguy and there it is