OMP Injectors vented or not?
 

I came across a few single turbo vacuum diagrams and wondered what the best way to set these up?

Capped?

Connected before turbo?
-filtered or not?

Connected after turbo?
-before Throttle Body?
-after TB?

Looking at the factory diagram it seems they are connected before the turbo and filtered. After reading a few threads about it, it seems people have connected them a few different ways.

Timely...


I've been thinking about this recently as well. All the stock setups have them plumbed in before the throttle body to see constant vacuum. I've never capped them. Either pull them altogether and pre-mix or hook them up like they're supposed to be. But why....

What pullzes me is that the only check for them in the FSM is to be able to blow through the nipple but not be able to suck air through the nipple. So what's the point of putting a constant vacuum on it? And if the vacuum is applied to keep the check valve closed at all times, why put a check valve in the injector?

https://www.rx7club.com/showthread.p...light=metering

we spent a day or so playing with em, if you hook it up wrong, the car uses a lot of oil and smokes. i'm a little foggy about the why's of the setup though.

so the car smoked with it hooked to vacuum in front of the turbo, and when its just open to atmoshpere, its fine....

When you look at any of the FSMs (S4, S5, S6 turbo or NA) they show them being connected pre-turbo or pre-TB (NA). I'm foggy on how they function as well. Even more curious about your results.

I'd say choice #2, between the air filter and compressor housing like stock. I've been told that they definitely should not see boost. You can see where I sourced the constant vacuum in my sig picture, I just drilled into the comp housing inlet and used a 1/8 NPT nipple.

Rich is correct, #2, between the air filter and turbo compressor inlet.
Stock is that way and so are mine.

I was reading on a past thread that they were designed that way so when the engine was shut off it would not pull the remaining oil through the line into the motor; thus on start up it would not smoke badly. The vacuum caused by the turbo seals one part of the oil injector so that the oil can be pumped through the injector line. When there is no vacuum or little vacuum from the turbo (right after engine shutoff), the vacuum inside the engine from the rotors, as they make their last revolutions, is not going to pull the oil from the oil line but instead pull air from the line connected before the turbo. Having them capped off just reenacts what having them connected before the turbo will do; except you will get smoke on start up. Hope that makes sense. Like i said i read this on a thread here. And as far as i'm concerned there is no right way to do it. everyone has their own setup.

well a few have mentioned about the second gen setups and that is how i am going to see about running them so if i can find a pre T/B port i will let you guys know, that should be an alternative for those who have large single with a filter right at the turbo.

One of the vacuum ports right behind the throttle body on all the 2nd gens actually is ported to a source in front of the TB. The port entry is right between the secondary butterflies. It's an easy matter to take some light compressed air and blow into that port and feel where it comes out. That nipple is where you'd hookup you line to the injectors. Or if you have the plastic spacer out you can easily identify which port it is.

i already know which are vacuum and which are pre T/B air on second gen models but never needed to know on 3rd gen models until now so i think it would be beneficial for this reason to find out which/if any of the ports on the 3rd gen UIM are ported before the throttle plates for the OMP bleeders to function properly without having to hack up a intake duct or lose that small amount of vacuum from the engine for tuning reasons.

though this whole issue probably is being over thought out, with the stock configuration is vented to pre tuned air in the engine so they probably draw in such little air it hardly is even worth the thought but i just prefer to do things the way i think is right.

this is any interesting thread for me because i have had a problem with my car lightly burning oil on startup. i replaced the turbos, and as far as i can tell, the oil rings on the rotors are all fine (doesnt smoke on decel, and light smoke for one minute or so when starting stone cold)
i looked into this a little and found that the stock oil injectors have a diaphram in them that can tear and the oil can leak out in either direction: into the motor, or back out through the vac line into the primary turbo inlet...
anybody heard anything about this?

I too have thought a little about this. I am currently going from a 85 13b -se motor which is NA to a Cosmo 13b in my FB. I noticed on the Cosmo setup that they had the OMP vacuum lines plumbed into the intake castings before the turbo. I was thinking on hooking them back this way when I go with my single turbo setup.
I too was thinking that this might cause too much vacuum as Jacobartmill is mentioning in the sense of them pulling the oil up into the vacuum lines, or just pulling too much oil through all together?
Maybe this is over thinking in some sense...but sharing thoughts about such a general idea allows you to think outside the box. ;]

well with this single project am working on there is no where to place a line prior to the turbo so i figured i would hunt it out some. i wound up tracing all the ports on the UIM and none of them are port or "fresh" air prior to the throttle body, so... i wound up pulling a breather cap off a spare solenoid and ran the oil injector air lines to that, not much else of an option aside from drilling and installing another port on the T/B, not worth the effort for no real noticable difference though.

They need to be hooked up to filtered, metered, open air pressure.

before the turbo is NOT vacuum.

Putting vacuum or boost on them will make them not function properly.

They ensure that the oil metering pump is actually doing the metering insted of the motor vaccume sucking in extra oil. When the motor is on it's intake stroke their design allows fresh air to be sucked through the nozzels insted of the motor sucking in extra oil.

This may also help atomize a small amount of oil in the nozzel to help lubricated the rest of the chamber.

metered air applies to second gen models, seeing how this is not generation specific and second gens have fresh air ports it doesn't apply to third generation models with no AFM metering the air so the air prior to the turbo is just filtered unmetered air which in the stock configuration wouldn't affect the tune of the engine or mazda would have put an extra nipple on the UIM.

So I got bored and curious today and cut an oil injector open. Pics below. Basically there is a check valve in there. It will only allow air to flow from the vacuum nipple into the injector, sealing against air moving out of the injector. But we new that from the FSM injector test right?


http://www.ludwigmotorsports.com/rx7...r/assembly.jpg

http://www.ludwigmotorsports.com/rx7...assembly_3.jpg

http://www.ludwigmotorsports.com/rx7...assembly_2.jpg

http://www.ludwigmotorsports.com/rx7...checkvalve.jpg

http://www.ludwigmotorsports.com/rx7...eckvalve_2.jpg


This last pic is of the injector bottom with the check valve removed.


http://www.ludwigmotorsports.com/rx7...r/injector.jpg

^ I completely agree. I looked into this about a year ago and spoke to Rob @ Pinapple and Jim Medero (sp?) at Racing beat. Both said that it should see filtered air and that is all.

thats interesting.

maybe i'm missing something, but what i am wondering what happens when the check valve sticks (open or shut)...


is it possible that the vac source for the oil injector could pull the oil out of the injector through to the vac source?

here is the FSM procedure for testing the FSM, btw. not too complicated :)

https://www.rx7club.com/forum/attach...hmentid=218632

well then what was the point of mazda putting constant vacuum on the oil injectors from the factory?

Like Drago correctly pointed out a pre-turbo source is not vaccum. It's atmospheric.

+1

if you have it hooked up to a vacuum source then oil is being pulled out of the injector and into the manifold whenever vacuum is present and not being metered in small amounts into the rotor housing as intended.

the compressor inlet doesnt create a vacuum?

i'm not trying to allude to some super-hidden point -just curious, because apparently i'm a little confused

No. Ever mistakenly hooked a vacuum/boost gauge up to a pre-throttle blade port? No vacuum.

So let's expound on this a bit...

Last week I found an injector that failed the FSM "blow" test. It worked exactly backwards. Would not allow you to blow into the vac port but would allow you to blow from the injector end out through the port. The injectors, as they were installed on the engine, had vacuum caps on them. What should the result of the failed check valve and the fact the inejectors were capped be?

i would think it wouldn't let any oil to the chamber and blow it backwards up through the vac line if the check valve was broken.

now capping them, i'm not sure what that would do, probably just stalemate everything, or blow the oil back at the mop

I spoke to Don at Marvel Speed, Keith at KG Parts, and Ari at Rx7.com. They said to just connect them to a vacuum source on the upper intake manifold. I can't recall if it had anything to do with my 3mm seals.

The vac lines on the OMP injectors need to be plumbed to a filtered source that doesn't see positive manifold pressure. That means either in front of the turbo or to their own dedicated filter. Here's why.

Some other good info in this thread:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/omp-how-works-modification-amecu-discussion-regarding-premix-60867/

Unfortunately there's some bad info in that thread as well ;) Always seems to happen when an OMP discussion comes up.

i am going to go do the blow test on my oil injectors momentarily to see if they could be the reason for my small smoke on startup

my oil injectors allow air to flow through them both ways... no bueno

unfortunately they gave you bunk info then. it is quite surprising how many people don't know how the oil metering system really works, alot of guys opt for pre-mixing and omit it and never really took the time to understand it.

Ok well for the omp, would be ok to just tee of my wastegate signal line coming from my intercooler pipe just out of the compressor housing?

not sure that that would be a wise place to tee into because if your injectors are faulty or the natural pressure being forced back into that line then it could cause your boost level to be erratic. the injectors really should have a port all to themself.

teeing into the wastegate line is always a bad idea, most people do not realize the importance of that one single line.

I have ran them capped and uncapped and made no difference in oil consumption or burning. We have worked on many cars with them capped and didnt see any issues.

Jason

i generally trust in mazda's engineering and try not to question the people they paid to actually test the setup that was installed in all series of 7's. i would think over many years they would think, "hey, do we really even need these injectors to be vented?"

anybody know the mazda part # for the stock fd oil injectors?
i did the blow test on both of mine last night (at the same time with the vacuum tee) and they let air in AND out of the housing :(

I would definitely not do that for a few reasons. Best to do it the way the factory does, and source atmospheric (not vacuum, lol) air from between the air filter and compressor housing. I just drilled my comp housing (11/64 bit I think?) and tapped it for 1/8th NPT, then threaded in a brass bung bought from pep boys along with some teflon tape. Works like a charm :)

Thanks Rich....you gotta pic? I know I'm a caveman, I like pictures! :-P

i'm assuming you drilled it on the inlet and not the compressed side? :)

N3G1-14-631

About $25-30 from your neighborhood dealer.

You can kind of see the nipple with the blue vacuum hose coming off the compressor inlet in my signature.

Jacob, yes, as I mentioned, to source atmospheric air you'd have to drill into the inlet, if you drill into the compressed side you'd be making a nice pressure source for your wastegate, but not a good choice for OMP injectors or oil filler neck :)

should i have my oil filler neck breathing through the stock turbo inlet? i have it hooked up to the UIM with a check valve

There are 2 nipples----the horizontal one goes to the UIM with a PCV valve inline, and the vertical one (pointing down) goes to a hardline, which then feeds to the black plastic elbow bolted to the front compressor inlet.

the three methods all work fine i would say though, you can either put a port prior to the throttle plates, vent them with a vent cap off a spare solenoid or place a line prior to the turbo that is filtered. obviously with the FD and the MAP sensor based system it doesn't necessarily need to be plumbed back in anywhere so long as it has filtered air. on second gen models the metered air is very important which is why they plumbed it back in but why not do it like the FD setup and hook it in prior to the turbo? my guess is either setup works they are relatively similar.

So what are the consequences of running a vacuum signal from the upper intake manifold to the omp injectors instead of the compressor housing?

i ordered a pair of new oil injectors today from ray @ malloy mazda 24.50 a piece.

jacoh

haha.... this is only the beginning LOL !!!!!

I am truly amazed by the longevity of this thread!

hey i actually thought 24.50 was pretty cheap :)
its not often that i will actually buy parts from MAZDA.

If you'd ever bother signing up with Mazdaspeed you could get them cheaper.