PCV barb connected to IM plenum?

[Ceddy]

Was going to use PCV barb for MAP Sensor connection.

But it seems to be clogged.

Does anyone know if the PCV barb is plumbed differently then the other vacuum ports on the Intake Manifold?


Thanks.

 

[andy4g63]

I don't know for sure, but it shouldn't be. The way it works/PCV, it closes under boost and opens under vacuum, so it should be a decent source for MAP sensor.

 

[Ceddy]

The PCV Valve on the valve cover does the check valve thing.

I would like to use the PCV barb because it is big in size, and I'm running out of vacuum ports.

But not sure if they plumbed it some strange way for PCV use.


I have a Cyclone IM [No EGR], on a 1G Head in a 2G, so possibly something could not be lining up. Or maybe some RTV is clogging this barb or something.


Wondering if anyone else has used the PCV barb for other things beside PCV use, with no problems???


Thanks.

 

[Calan]

The only difference is in the size of the ports, and where the vacuum is felt. It would probably work, but personally I would get as close to the TB (straight off the plenum) as possible for the fastest response with a MAP sensor.

You could always drill and tap the IM for another fitting.

EDIT:

This is for the stock IM...I have no experience with the Cyclone so I don't know how it's set up.

 

[snowborder714]

I'm not sure if there's any great spots on a Cyclone to drill/tap as there is on the 1g manifold. I looked at mine and didn't see any place that really said "Put a MAP sensor here".

 

[romeen]

The vacuum nipple which connects to the PCV valve is tapped into a rail which runs the width of the IM and connects to each IM runner individually (pic #1) as opposed to the other nipples which are tapped into the plenum.

In pics #2 and #3 the small openings which you can see directly above each of the runners without a flapper are for the PCV system. The ports are located between the middle and last sections of the IM so whether you are using a 1G or 2G head should have no effect on it. In pic #4 you can see the "U" shaped grooves which the ports match up with.

I can easily blow through the nipple on my Cyclone and air comes out of all 4 runners. So it does sound like you have some sort of obstruction. Those ports are pretty small so they may be gunked up. Or if too much RTV was used on the gasket it might have squeezed out and blocked the ports. One other possibility is if someone made a DIY gasket that goes between the middle and last sections of the IM but didn't cut out the "U" shaped portion in turn blocking the ports. Pic #5 shows my DIY gasket compared to the oem gasket.

Hope this helps.

 

[Ceddy]

Thank you very much.

I knew there was something weird with the PCV port, but its been a while since I put it back together.

I bet some RTV got in the first opening and is blocking the rest off.


It looks like there could be some artificial, venturi vacuum, using the PCV barb, probably not best for a MAP sensor.