Good day all ,
Thanks for taking the time to read this. I have a 4x4 97 blazer 4.3.

Lately was struggling to start. Then this am she fired up and it's very high idle and alot of hissing air sounds coming from driver side firewall area. Then after 15 seconds it stalls. Repeated and she stayed running but very rough. Put into reverse and stalls out. Can any one point me to what I can look at?

 

This shows the top of the engine, driver side:



#1 is the PCV valve
#2 is the vacuum line going to the PCV valve
#3 is the fitting that attaches to the plenum
#4 is the vacuum line that feeds the 4WD & HVAC systems

Any one or more of these can leak vacuum and cause a hiss sound, and increased idle speed..

 

Thanks for the reply.
Question. Is #1 and 3 supposed to come out of their respective spots so easily? Under the hood they both are wobbley and I noticed upon pushing them back in she's running normally and stays running. Should this piece be replaced?

 

Where the pcv valve connects to the plenum it is loose. Should this make a solid connection? and not be loose? I'm afraid if I hit a bump or something it will pop out and stall

 

If #1 doesn't stay in tightly, (it just slides in) the rubber grommet needs replacement.

If #3 doesn't stay "locked" in, it may have come loose, or broke. It pushes in and turns a bit to lock it in place. There is an O ring that seals it so it doesn't leak vacuum. Auto parts store should have it. Not sure if this is the correct one for your 97, so check with the store. Dorman - Help PCV Valve 47026: Advance Auto Parts=