Sharing vaccum lines?

[JeepsAndGuns]

OK, so my intake manifold has a extreme shortage of vaccum fittings. I have 4 in total. 1 is connected to the PCV vale (I think its the one originally intened for the vac booster, but since I have hydroboost, its free) I then have the 2nd one connected to the MAP sensor. 3rd one I have the fuel pressure regulator hooked to, then last one is the CCP and heater controlls connected with a T fitting.
So I'm needing to install a MAT into the hole in the intake where the fuel pressure regular is hooked to now. So my question is can I "T" into the MAP sensor hose with the FPR? Or will it cause wonky MAP readings? I figure since I already have the ccp and heater doors hooked to one, its the only other option I have. I dont really want to pull the intake to drill/tap it for some more ports.

The port the MAT would go in is on the upper part of the #8 intake runner. I know on the 7730/tpi it threads up into the bottom of the upper intake. SO the only other option I could think of would be to install it in my air intake bonnet. I could remove it and drill/tap easy. BUT, would it throw off the MAT readings since its not in the actual intake? I was thinking possiably on the bottom at the intake of it as close to the TB as I could get it.

What do yall think? Pic of the intake bonnet (from when I was installing it)

[EagleMark]

T ing into MAP is what is done on TBI with vacuumed referenced FPR.

Where exactly is your PCV plumbed? It can't go into a single intake runner or it will cause a lean cylinder.... ie WB V shaped dips...

[RobertISaar]

GM spliced a LOT of lines together... and for good reason, it still works normally.

i'd just splice certain types together... i.e.: MAP and FPR together are fine since neither should be transporting fuel vapors(CCP) or crankcase fumes(PCV). just keep the sensitive stuff away from potentially corrosive lines and you'll be fine.

[gregs78cam]

Also remember the PCV more than likely has some "air" flowing through it, so it won't give a full vacuum reading, if any at all if your PCV is set up like a stock TBI where fresh air is drawn from air cleaner through engine and into intake.

[EagleMark]

What they said... I don't think he was thinking of T ing into PCV, it won't work, it's not vacuum above the PCV valve, just air flow.

The reason I wanted to know where the PCV was plumbed was do to an issue he has in another thread.

[Six_Shooter]

GM T's the FPR and MAP sensor together in many applications.

when connected to a MAP sensor or FPR, the vacuum is not flowing, but more of a spring. Many people have a hard time visualizing just how the air is not flowing, but only at most shifts a little bit back and forth with in the lines, much like a spring that that is pulled apart will want to close when the tension is released (provided you use the correct type of spring).

[EagleMark]

Good explination!

Also the reason some cheap vacuum lines colapse.

[JeepsAndGuns]

I knew how vaccum works and doesnt "flow" per say. I just was unsure if the moving diaphram in the fpr would cause any strange readings on the map, I know they are sensitave. Glad to know it will be ok, saves a little headache.

The port I am using for the PCV is on the top center of the intake, just behind and below the throttle body. About a inch to the side, is the line for the map. The other two are in the # 6 & 8 runners. Here is a couple of pics showing the intake. These were taken right after I bought it. You can just barely see the two drilled holes on the backside of the TB opening. Center one is pvc, the one next to it is the map. The ones in the two runners, the large hole is where I will be mounting the mat (currently used by the fpr) then the smaller one is for the ccp and heater controlls.

[EagleMark]

I can't see where MAP and PVC are outside but looks like the openings are inside under throttle body/rear? That is good.

The spot where FPR is and where MAT is going is good, Actually moving the FPR to T in line with MAP would be a good thing! Single intake runner vacuum can and usually do pulse vacuum ie.. not steady/solid. You may have found some data issues.

[JeepsAndGuns]

I can't see where MAP and PVC are outside but looks like the openings are inside under throttle body/rear? That is good.

I didnt have any actual fittings installed into the intake at that time, but yes, you can see the holes on the inside rear under the the TB. They are just straight through holes.