Just to clarify... Your PCV valve is still connected, isn't it? That's where the vacuum is applied.

In theory, the tube you're referring to is there to supply filtered air to the crankcase that the PCV valve is sucking through into the intake manifold.

However, as you've probably noticed from the residue left behind, oily crankcase vapors often go the other way into the opening of the throttle body and muck it up.

One solution is to use an oil catch-can. Another is to use a separate small air filter instead of having the tube you're referring to connected to its factory location.

kharmata wrote: I am not convinced that this should be disconnected.

I certainly wasn't trying to convince you. Mine's connected.

This mod that Kevin has, has been done to Mine, Brian's, Tims and several other Fiero's including Nigel's before he left.  It keeps the engine from inhaling HOT Oily air under WOT situations. It saves the IAC from getting mucked up and improves both throttle response and gas mileage.

Kevin's issue comes from the fact that he has fairly extensive amounts of blow-by from bad compression rings in his engine.   Its a catch 22, the blow-by is so bad that it is making the engine run poorly, so it should be removed to make the engine run better, but on the flip side, the smoke is now exiting the K&N Filter connected to the valve cover as well as allowing a small bit of oil from the crank case to build up in the small valve cover breather filter. 

Short of rebuiding the engine, sounds like an oil catch-can installed in-line with Kevin's breather hose is the route to go then.

I made a catch-can years ago and used it on a 1970 Nova that was puking copious amounts of oil into the air filter housing. Worked great.

Thanks guys.

I am currently trying a middle ground.  Sort of what Patrick mentioned but without the catch can.  I installed a "t" section on the breather tube and connected my K&N filter so now the smoke is sucked up but the engine is paritally vented as well.  Not sure if this completely minimizes suck on the bad rings but I am sure it helps and also keeps the smoke exit to a minimum. 

Any other thoughts?

kharmata wrote: Not sure if this completely minimizes suck on the bad rings...

Honestly, there is not enough "suck" on that breather tube to affect crankcase vacuum at all.

It's the other tube, the one that's connected to the PCV valve and the intake manifold that supplies all the "suck".

kharmata wrote: With the breather open to free air the pcv will never provide any vacuum to the crankcase...or am I wrong here?

It sounds to me like you've got it wrong.

The intake manifold is sucking air from the crankcase (through the PCV valve) whether you've got the other breather tube connected in front of your throttle body or not.

The following is taken from  http://autorepair.about.com/library/faqs/bl616h.htm - Here .

SYSTEM OPERATION:
The PCV system prevents blow-by gasses from entering the atmosphere by routing blow-by gases into the intake manifold through a vacuum controlled ventilating valve and a hose while allowing proper crankcase ventilation.

Blow-by gases mix with the air/fuel mixture and are burned during combustion. When the engine is running, fresh air is drawn into the crankcase through a tube or hose connected to the air cleaner housing.

This system is still the same as it was when it was first used in 1961.

PCV VALVE OPERATION: The PCV valve consists of needle valve, spring and housing. When the engine is off: the spring holds the needle valve closed to stop vapors from entering the intake manifold. When the engine is running: manifold vacuum unseats the needle valve allowing crankcase vapors to enter the intake manifold. In case of a backfire in the intake manifold: the valve closes, stopping the back flow and preventing ignition of fumes in the crankcase.

During certain engine conditions more blow-by gases are created than the ventilator valve can handle. The excess is returned through the air intake tube to the air cleaner and carburetor where it is burned in the engine.

A quick check of the system can he made by pulling the end of the PCV valve out of the valve cover and placing a finger over the end of the valve to block the air flow, while the engine is idling.

• A vacuum should be felt and the engine speed should drop approximately 50 rpm if the system is satisfactory and no further testing is necessary.
• If there is no change in engine speed a clogged system is indicated, proceed to the next step.

To isolate the problem, remove the PCV valve from the hose and note vacuum felt and any change in idle speed.

• If the ventilator hoses and carburetor passages are clear, a strong vacuum will be felt and the engine idle will change drastically or the engine will stall when the end of the hose is uncovered. If this occurs, the trouble is in the valve.
• If the engine continues to idle approximately as it did before the hose was uncovered, the hoses or carburetor passages are blocked.

As for the other end, the air intake side, there is little that can go wrong. As long as the hose or breather filter is not clogged, air has to enter the system.

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Kevin, I've indicated in red the part that especially applies to your situation.

kharmata wrote: Patrick, I get that part. But internally (crankcase) are they not both opening into the same big space (crankcase)...? I think our perspectives are slightly different here. (In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure) Yes I get this part.

I've added to my earlier post to try and make my point(s) clearer to you.

kharmata wrote: I maybe getting it finally!

About time!

Don't feel bad. It's a very simple system which is often completely misunderstood.

Kevin, if I had excessive blow-by which was resulting in the fouling up of the inside of my throttle body (TB), this is what I would either make or buy to install between the front valve cover (on a 2.8) and the fitting in front of the TB.

It's what I mentioned earlier, an oil catch-can.

In my home-made version I used years ago, I used plastic pot scrubber pads to provide the surface area for the suspended oil particles in the crankcase air to condense on. The oil then drips down and collects in the botton of the container. You'll notice the tube directing the oily air goes right down into the mesh material whereas the tube directing the "clean" air draws this air from the top of the container.

You require a way to drain/empty the collected oil out of it, but the container needs to be airtight while in operation.

On a properly operating PVC system (healthy engine), many people install a catch-can like this between the intake manifold and the PCV valve. This is to prevent a lot of the suspended oil in crankcase air from being sucked into the intake manifold/combustion chambers, yet still providing positive crankcase vacuum and the burning of crankcase gases.

On your worn engine, installing the catch-can where I've indicated instead would help reduce/eliminate your TB from being mucked up with oil due to excessive crankcase blow-by.

Very creative - So far I am just doing the breather thing and live with a bit of oil lube.   Cool idea though.
Best of all I wanna new/rebuilt motor and trany so I will suffer until it dies or gets replaced.