There is a vacuum tube that comes out of the passenger side valve cover and connects to the passenger's side of the throttle body. I'm assuming that it is used to recycle vapors from the engine, but does it do anything else? Does it have to be connected? I'm asking cause onthe inside of the valve cover where this tube connects there is some kind of screen orn splash guard to keep oil out of the tube. This must have become blocked or damaged because my Iroc developed a whining niose st normal operating temperatures and the rpm's started jumping around while driving. I found that by disconnecting this tube the noise goes away but the idle rpm's drop. When I plugged this tube and drove my camaro, it has never drove better. For the first time since I've owned the car, the engine light has gone off. Will this hurt anything by keeping it plugged or should I look into what's actually causing the problem? Thanks

 

That tube supplies fresh, filtered air to your crankcase on the passenger side. The bad air is removed by the PVC valve on the drivers side. Yes you need it. You might want to check your PVC to see if it is operating correctly, which may have been the problem in the first place.

------------------
Mike Metzler (Desert86Roc)[*] Webmaster: SpeedWorldMotorplex.com[*] Click Here For 86 IROC 305 TPI (406 build in progress) Page

ET's @ 1250 ft[*] 14.28 @ 95.461 mph (uncorrected, NOS, no headers)[*] 15.365 @ 86.785 mph (uncorrected, headers, no NOS)
<><

 

Would a "breather cap" work just as well? I have Moroso die-cast aluminum valve covers with the round breather in the pcv hole on the passenger side. I would use the correct pcv valve on the driver's side like factory, just the passenger side would have the breather. Is this going to be a problem? This is on a brand new 350 engine & TPI system with zero miles.

------------------
'92 RS, ZZ4 10:1 350, Edelbrock 6085 heads, Crane 208/214* 467/482" 112* cam, GM/LT4 1.6 roller rockers, Edelbrock Hi-Flow TPI base, runners & 52mm TB, SLP/Jet-Hot 1-5/8" headers, Catco 3" cat, Flowmaster 3" catback, Hughes 2500 stall converter, stock 700R4, 1LE driveshaft, Auburn Pro posi w/3.42, 17x9" SS rims w/BFG tires, Medium Quasar Blue w/white SS stripes, 48,000 miles....

 

The PCV valve was just replaced in the fall so it should still be good. I'm confused on how the tube supplies air to the crankcase since the air flow is coming from the valve cover and going into the throttle body.

 

It's like (or is) a CCVO (Crankcase ventillation hose) on a bike...yes you need it for the fresh air.