Intake Manifold Vacuum

[SethChr16]

I have a 1998 Explorer, 4.0 SOHC with the VIS. The CEL is on but I have not checked the codes yet. I think there is too much vacuum in the intake manifold because the hoses from the manifold to the PCV valve are being sucked shut! I checked the PCV and it was moving freely but I cleaned it anyways. Thought maybe there was negative pressure because of an intake leak so I replaced both the upper and lower intake gaskets but that didn't fix it. I have cleaned the IAC and that hasn't changed anything though I have not been having any idle problems. Anybody have any ideas?

 

[2000StreetRod]

pressing against the firewall

I doubt that your intake manifold is experiencing excessive vacuum. My hoses were flattened and worn due to pressing against the firewall for many years: SOHC PCV Valve Mod thru 2000