Simple question; are these lines seeing vacuum at any time? or are they just used so there's no unmetered air entering the engine?

 

The suction comes from the rotors intake stroke. It sucks air from the front of the throttle body. Metered air it is.

Suction never comes from the direction of the throttle body.

 

Because of the source's location (front top of the TB), I'd have to guess they're seeing at least some vac...or maybe it's actually a positive pressure, compared to the manifold vac the actual injectors see???

 

Wha? Open vac lines are variably a bad thing... The more vac on the manifolds from the n/a engine, the better. No open vac lines = better vac (everythign has to pull from behind the plates.)

There *are* however a couple of nipples on the TB that pull from in *FRONT* of the TB plates. These lines are meant for fuel injector bleeds and will lessen manfiold vacum because they can't be "shut off" via the TB plates closing.

However... don't ask which ones they are-- no one seems to know. I ended up making my own spider rack on the intake tubing before the plates to make nipples for the injector bleeds as opposed to figuring out which nipple goes stock before the plates.

Anyway, all vac lines after the TB plates will have vac anytime
1) engine is running
2) not at WOT

At WOT (in theory anyhow) the TB plates restrict no air vac from the manifolds and hence there is no vac. When the plates are closed however, the TB plates restrict air and vac, causing a suction on the back of the plates, this suction is what the vac is.

You'll see the most suction (generaly) on decel of a high rev if the plates snap closed. (Plates will not snap closed stock however-- they are made to close slowly, even if you instantly let your foot off of the pedal).

I think I ccovered this topic pretty well-- can't think of anythign to add.

Oh open vac lines = lelss vac, less power, higher idle (to a point to which the car has so much unmetered air that it can't idle.)

Vac lines before the TB plates (fuely bleeds) raise idly right around 25rpm per nipple in my experience.

 

you covered the topic well, but you didnt' answer the question directly.

I'm talking about the nipples on the back of the oil injectors, that connect to the same pipe that the AWS Solinoid connects to. With the AWS closed, as it is after the warmup; it seems to me they'd be seeing almost no vacuum.

 

You seem to have missed everything posted above. They don't ever see vacuum from the manifold! The vacuum comes from the engine itself, and the "vac" lines are where the air is sucked from. The lines are connected to passages in front of the throttle, so there is always air being sucked through them, because the engine is always sucking air. The AWS has absolutely nothing to do with any of this.

 

I thought I answered the question very well indeed. Liquid....your making me lose my self confidence.

The suction comes from the threaded side of the oil injectors. Thats from the intake *stroke* of the rotors. The air being pulled into the rotors comes from infront of the throttle body.

Light up a good Havana and blow smoke into the nipple on the intake where the oil injector spider connects. You WILL SEE the smoke exit the approx 1/4 inch hole in front of the throttle body. Been there, done that. This answer is very similar to my first answer.

 

long post short; the vacuum lines that go to the back of oil injectors are there so the motor takes in metered air.

-post over-