Should my 5.0 hold vac after it's been shut-off?

[Booksix]

Just re-did a bunch of old, plastic vac lines and picked up a vac gauge to check what I had (16-17 at idle - about 750-800 rpm i believe) and I was just wondering if the engine should hold vac after it's shut down... When I shut my car off, I immediately hear all the vac escape is a loud whoosh and the gauge drops to zero instantly... Just wondering if this is normal.

Also, when I give my gas pedal a quick-tap (about 1/2 throttle) and right back off I hear the air suck in through the filter and then a brief second later the engine revs... It's a bit of a hesitation (currently pull no KOEO codes)...

 

[BigHairyMonkey]

sounds about right.

 

[cjones]

if you are teeing off between the vacuum reservoir and the check valve it should not leak.

if you're tapping to the intake manifold then going to 0 is normal

 

[Booksix]

No, I'm pulling from the blank spot on the tree... thanks guys...

 

[HISSIN50]

I have my gauge on the same spot (I'm SD so I have a permanent gauge in the car). The vac does drop off as fast as the needle can fall (once the car is shut off).

The noise you hear at the TB can be normal, esp if you have the silencer removed and a gauze element.

Good luck.