Vacuum gauge diagnostic question

Nissan11

Well-Known Member
Joined
Nov 29, 2005
Location
Marston, NC
Iim trying to diagnose a running hot issue in my Nissan frontier crew cab.
I hooked a vacuum gauge up to a port on the back of the intake near the firewall. It was my understanding that a healthy motor will idle between 17-22" and when the throttle is blipped, will drop to 3-0, then return back to its original position.
My truck shows 17 at idle, but when I blip the throttle it only drops to 15-16, then returns back to 17.
Here is a pic at idle.


Port

ai130.photobucket.com_albums_p275_nissan11_Mobile_20Uploads_IMG_5298_zps5a8c8b87.png



Idle

ai130.photobucket.com_albums_p275_nissan11_Mobile_20Uploads_IMG_5422_zps3e9b5a82.jpg









What does this mean? Am I hooked to the wrong port?
 
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