Pulling PCV kills engine

[feedthemonkey]

I went to check/replace PCV valve on my 93. Haynes (1-20) says, "start the engine and allow it to idle, then disconnect the PCV hose. If vacuum is felt, the PCV valve system is working properly."

When I pull the hose, the engine immediately dies.

What does that tell me? (I think I felt some vacuum as I started to pull the hose, but once off, the engine shuts down)

 

[BrooklynBay]

A sudden large vacuum leak causes it to stall. It might not start with the hose unplugged. Try the same test while raising the idle to 2,000 rpms.

 

[J_C]

If it's the original or very old PCV, I'd just go ahead and replace it, considering inexpensive part and you're already in there.

 

[feedthemonkey]

If it's the original or very old PCV, I'd just go ahead and replace it, considering inexpensive part and you're already in there.

for sure. The part was like $3. I replaced it. ...but, I still want to hunt down the reason for the engine stall when I pull the hose in light of the Haynes manual suggesting it will not stall. Per @BrooklynBay I will try with a warmed up engine and at a higher RPM before reporting back.

 

[J_C]

Haynes manuals, they tend to describe generic procedures then copy/paste them into every vehicle manual to generate # of pages. I've found them less and less useful as the years go by, especially the physical books with rather crude little drawings. I"m more hi-res. picture, oriented... or youtube videos, if the producer knows how to do it well.

One thing you could do is hook up a scan tool capable of live data and look at the long term fuel trims. If it's already running too lean and more than single digit positive trim to correct it, you might have a slight vac leak elsewhere, or dirty MAF sensor, or low fuel pressure, and then the extra air from the PCV disconnected is just enough to stall it, OR could just be Haynes didn't really test this on the particular engine if cold will stall anyway.

If nothing else seems wrong, I wouldn't worry about it.