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.