3rd Generation Specific (1993-2002) 1993-2002 Discussion including performance modifications and Technical Support Sections.

How much Vacuum do OMP Nozzles Need to Open?

Old 06-16-09, 09:25 PM
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I'm getting confused now... I thought I had this lol.

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Old 06-16-09, 10:18 PM
  #27  
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Originally Posted by arghx View Post



The above pic is incorrect in both ways. For one, the factory has your blue air nipple to the OMP nozzle attached to the pre turbo inlet (constant vacuum source) not after (which is both vacuum and boost). The location in your pic will subject the air line to boost. You should never have boost pressure at the OMP nozzle nipple. The only way the OMP nozzle is subjected to pressure is when the combustion chamber itself is under boost. When the combustion chamber in under pressure (I'm talking pre compression event of the rotor), everything in the intake track (except pre turbo inlet) is under boost pressure.



Edit: I just notice that you were referring to the 2nd gen setup. I don't know the routing of that set-up but your explanation of having a vacuum in a pressurised environment is wrong. You can't have pressure and a vacuum in the same location. Example... The water main to your house is under pressure. Every line it's attached to is under pressure (bathroom, kitchen, exterior line etc). When a turbo is making boost pressure, everything in the turbo outlet becomes pressurized.
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Old 06-16-09, 10:39 PM
  #28  
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arghx the FD in stock form has the oil metering injectors air line connected before the turbo. This is the source they refer to as fresh air. The amount of vacuum created by the turbo at during idle is not enough to offset the vacuum created by the engine. The only significant amount of vacuum created by the turbo would be under boost, but in this case the check valve would be closed.

I don't think the air port is for atomization. The nozzles mostly just dribble oil out much like a chainsaw blade receives lubrication. Also I never noticed the compression stroke having an effect on either the oil metering air ports, in which I had a check valve in 1 fail, or on the injector atomizing line. There is no check valve for this line and it will draw a constant vacuum when not plugged or connected to the boost pipes. There is no pulsing of air between intake and compression stroke. But under boost there is definitely pressure from the other side. Both these lines seem to behave similar to any other connection on the UIM or LIM nipples. Positive pressure generated under boost and negative pressure under deceleration and idle.

So the options available are:
Like a Stock FD: Which is right before the turbo inlet
Vented: nothing connected but could allow unfiltered air to enter under vacuum situations
Vented with small filter(s): Allows them to vent without sucking the oil out of the lines keeps air clean

Connected like T2:....? I never knew the T2 was connected to the hard pipe before the throttle body, did these models have a check valve built in? If not this might explain this method. Sounds like this is another option though mazda did away with this design for some reason?
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Old 06-17-09, 12:11 AM
  #29  
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Regarding the T2,

From the factory, the OMP lines are connected to a splitter which connects to a nipple on the UIM. That nipple is a passageway that goes before the throttle plates. It sees boost all the time. In fact, that line blew off on my car and cost me a motor. There is absolutely nothing wrong with the OMP ports seeing boost. Mazda does it from the factory.



On the FD under boost (according to a gauge),

Follow the green arrows from the precontrol and wastegate actuators. The air starts in the compressor outlet (boost), feeds the wastegate and precontrol actuators (there is always air passing through at least one of those actuators), and then goes into a chamber of some sort ( I've never looked at it closely ) that distributes it to the OMP injectors. The final stop is at the compressor inlet. As you can see, the air is being pushed into OMP injectors. There is no major difference among the series 4 through 8 in the atomization design.



a 2nd gen routing diagram. The OMP has a 4-way splitter for the 4 OMP injectors. The splitter is connected to the UIM. That port never reads vacuum, but I can attest to the boost that comes out of it as it blew off, causing a bad MAP sensor reading and serious detonation.

I don't think the air port is for atomization.
I disagree.




Also, I am hesistant to use the terms "vacuum" and "boost" because it leads to confusion. I don't want to get caught up in semantics and terminology. If the way I explained some of that seems contradictory, just ignore it or don't otherwise let it obscure my point.
Attached Thumbnails How much Vacuum do OMP Nozzles Need to Open?-omp.jpg  

Last edited by arghx; 06-17-09 at 12:32 AM. Reason: diagrams etc
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Old 06-17-09, 12:17 AM
  #30  
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Do you know if the T2 OM nozzles have a check valve built into them?
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Old 06-17-09, 12:33 AM
  #31  
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Originally Posted by Dudemaaanownsanrx7 View Post
Do you know if the T2 OM nozzles have a check valve built into them?
Attached Thumbnails How much Vacuum do OMP Nozzles Need to Open?-omp2.jpg  
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Old 06-17-09, 12:43 AM
  #32  
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Okay I wasn't sure if that was a description for the FD or the T2. I wonder why they changed the design on the FD and gave it just filtered air rather then pressurized air like it's predecessor. Maybe they were kinda learning as they went too. Which is why everyone is now so confused. lol

Screw it, just hook them up to something....... anything, including nothing haha.

Just make sure the check valve works or you will have a mess.
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Old 06-17-09, 12:49 AM
  #33  
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I wonder why they changed the design on the FD and gave it just filtered air rather then pressurized air like it's predecessor.
They do receive pressurized air, that's what I pointed out when I edited my last post which you may have missed. The OMP atomization ports are connected after the precontrol and wastegate actuators in terms of the flow of air. The pressurized air flows from the compressor outlet to the wastegate/precontrol actuators, to the wastegate/precontrol solenoids, and then either to the OMP injectors or back to the intake. It's no different than the charge relief valve venting pressurized air back to the intake. If anything were to be hooked in with the charge relief recirculation it would also be receiving pressure.

The overall design is the same between the 2nd and 3rd generation cars. But like everything on the FD, it's just more... confusing.
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Old 06-17-09, 01:08 AM
  #34  
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My car hasn't been stock for awhile but i'm fairly certain it connects to the plastic elbow on the front of the primary turbo, which would be filtered but not pressurized air
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Old 06-17-09, 03:36 AM
  #35  
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Yes even in the diagram you can clearly see the teal colored line connects to the plastic elbow on the primary turbo, this elbow doesn't have pressure the filter connects to this elbow. I don't know what the turbo control solenoids are doing on that line, either they vent back here somehow or the labeling is not clear, but I clearly remember the oil metering lines going to that plastic elbow which definitely does not have positive pressure.
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Old 06-17-09, 08:00 AM
  #36  
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^^Correct.
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Old 06-17-09, 10:32 AM
  #37  
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nevermind.
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Old 06-17-09, 02:35 PM
  #38  
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Ok good. arghx was confusing me lol. Thanks.

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Old 02-18-19, 09:03 PM
  #39  
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I read this and am confused. I just installed single turbo. I want to keep my omp. Do I route these lines to the turbo filter? Open to air with filter? Or just connect it to one of the unused ports on the UIM? or..other?
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Old 02-18-19, 10:52 PM
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From the factory, these OMP 'breather' lines get filtered air from the turbo filter. Running a new line to the turbo filter on your new setup should be fine.
Many people, myself included, have connected them to atmosphere using small breather filters. Doing this should be fine also.

Routing them to the intake manifold will cause problems, don't do that.
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