Vacuum ports / EVAP setup

[the_nayton]

There's three vacuum ports on the intake manifold of my 4.0. Two have connections on them; one is open.

1) is it safe for the one to remain uncovered, or should I put something over it?

2) the middle one is for my EVAP cannister, which I removed recently, but am uncertain if I got it & the vapor valve reconnected correctly. Did I get it right?

 

[KennethS]

Do not leave a vacuum port open. Cap off all unused ones.

 

[Rickyd]

Is the line running through the firewall to power the hvac connected?

 

[the_nayton]

Is the line running through the firewall to power the hvac connected?

There is no AC in my Jeep. The tube for the heater controls is connected & functioning.

 

[the_nayton]

Do not leave a vacuum port open. Cap off all unused ones.

Why does covering or uncovering the vacuum ports affect the RPMs of the engine?

 

[KennethS]

It’s called a vacuum leak. The air from the uncovered port is creating an overly lean air/fuel ratio.

 

[Rickyd]

It’s called a vacuum leak. The air from the uncovered port is creating an overly lean air/fuel ratio.

And it is unfiltered air going into the motor