2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

why do people mess with the OMP?

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Old Jul 19, 2007 | 07:11 PM
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why do people mess with the OMP?

srry if this is a little newbish, but i was just wondering, because many people do it...
Old Jul 19, 2007 | 07:15 PM
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Because, its a piece of **** that will **** up your car if it dies.

The fact of the matter is, a rotary engine should have run premix from the start, but selling a car that need to get oil in the tank while you fill up would not have been a great seller, so mazda had to find a way to mix oil in the cumbustion chamber without any hassle for the owner...hence, the omp.

When you dont mind the premix, block it off. You will ALWAYS get the right amount of oil at any rpms. It makes for no broke lines, no jammed omp (mechanic) or broken/non-working limp mode enabling electric omp.

Last edited by Spectator; Jul 19, 2007 at 07:22 PM.
Old Jul 19, 2007 | 07:17 PM
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from what i have read by SEARCHING and Rotary Literature:

Our cars are getting to be old enough where many of the mechanical parts will begin to fail (it's expected with age). IF your OMP FAILS you can kill your motor. By removing the OMP you're taking it upon yourself to do the OMPs job (search for PREMIXING). IF you're responsible enough to remember to add the oil after you fill up you will avoid the uncertainty: Will it fail soon? did it fail already? the failure killed my engine.

That's MY take on it. Others might have other reasons but that seems to be the consensus.

The S4 OMP CAN be removed and blocked off, because it is mechanical, without any adverse effects. The S5 is electrical and it might throw you some codes but i'm not 100% sure.
Old Jul 19, 2007 | 07:19 PM
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Does that effect the oil and filter in any way, other than halting consumption?
Old Jul 19, 2007 | 07:27 PM
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A failing mechanical (series4) OMP is almost non existant. If its working, leave it alone. If you have the time and skills, convert it to 2 stroke but you won't gain anything from doing that unless you are putting in a new engine.

You can put a mechanical OMP on a S5. You just have swap the OMP COntorl arm from the S4 TB onto the S5 TB. The HowTo is in my sig.
Old Jul 19, 2007 | 07:54 PM
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Originally Posted by nittoracer753
srry if this is a little newbish, but i was just wondering, because many people do it...

Because they're paranoid and don't know better.
Old Jul 19, 2007 | 08:09 PM
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i think its been discussed before that it costs more $$$ to rip it out because of all the 2 stroke oil you have to buy. but if my car was simply for racing or something like that id rip it out so i wouldnt be paranoid i replaced my oil injector lines and have driven my car around a bit and in one of the lines the oil still hasnt made it up to the injector. who knows how long thats been happening.

but yes in the end its paranoia
Old Jul 19, 2007 | 08:20 PM
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I also think that the OMP may not give even lubrication across the entire rotors' surfaces like premix will.
Old Jul 19, 2007 | 08:24 PM
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just a reminder, use the search for premixing. there are pros and there are cons (and don't say there aren't :P)

personally im going the 2-stroke route when i do my rebuild. new lines + s4 mechanical omp + 2-stroke oil = happy me
Old Jul 19, 2007 | 09:13 PM
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I also think that the OMP may not give even lubrication across the entire rotors' surfaces like premix will.
Actually it will. The small amount of oil atomizes in the intake which distributes the oil over everything.
Old Jul 19, 2007 | 09:19 PM
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pre-mix and lose that piece of garbage and all the carbon build-up that goes with it!
Old Jul 19, 2007 | 09:24 PM
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pre-mix and lose that piece of garbage and all the carbon build-up that goes with it!
? Premix is a royal PITA! The Mechanical OMP is by far not a piece of garbage. I can do without the carbon though. You also wont loose carbon by switching to 2 stroke.

Here are some in progress pics of my future setup, I have to add a grommet to the bottle where the tube goes into it. I had the idea of the OMP below. I just needed someone to weld SS tubing to it so I had TitaniumTT do the welding. Overall did a good job.



Last edited by RotaMan99; Jul 19, 2007 at 09:29 PM.
Old Jul 19, 2007 | 09:41 PM
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Originally Posted by RotaMan99
A failing mechanical (series4) OMP is almost non existant. If its working, leave it alone.
You're right.
The mechanical OMP almost never fails.
It's the OIL INJECTORS that fail.
They're supposed to have a built-in check valve that supposed to keep the oil in the oil injector / lines at all times.
Once that check valve fails, air gets into the lines, and you get periods where no oil is injected into the engine.

I've purchased brand new oil injectors that have FAILED in under 10,000 miles.
GO FIGURE.


-Ted
Old Jul 19, 2007 | 09:47 PM
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You're right.
The mechanical OMP almost never fails.
It's the OIL INJECTORS that fail.
They're supposed to have a built-in check valve that supposed to keep the oil in the oil injector / lines at all times.
Once that check valve fails, air gets into the lines, and you get periods where no oil is injected into the engine.

I've purchased brand new oil injectors that have FAILED in under 10,000 miles.
GO FIGURE.
The amount of air, if any, that can get in the line is so small you don't have to worry. The OMP will pump that air out in a second or two. I have also had the check valve fail but have never ever had an issue.

When you turn the engine off, the omp still injects oil which then wont be burned off so it will stick to everything. It my puddle up a little here and there but there will still be a thin layer of oil. So those couple seconds if needed to push any of the air out of the line, would be cover by the oil thats in the engine already.

Tell me how many engines failed due to a bad oil injector.

There is still nothing to worry about

Last edited by RotaMan99; Jul 19, 2007 at 10:00 PM.
Old Jul 19, 2007 | 10:33 PM
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In that case...

http://fc3spro.com/TECH/FAQ/premix.html


-Ted
Old Jul 19, 2007 | 10:45 PM
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I think removing the OMP is stupid and leaves you with no choice if you don't have 2 stroke at the time your filling up. I had a car with it removed and a few times I had to buy 2 stroke from a gas station because I fogot to fill my bottle up. But what if you were out in B.F.E. and they had no 2 stroke.

I now keep my OMP but run a little bit of 2 stroke to help and incase the OMP does fail then I should be ok, and if I forget to add 2 stoke then again I am ok.
Old Jul 19, 2007 | 11:32 PM
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I blocked off my omp and run premix instead. I have a 1oz pump attached to my bottle of Valvoline multi purpose 2 stroke, so it's a mess free operation. 1 pump = 1 oz.

I didn't feel like switching my front cover anyways. Maybe when I rebuild the motor I will.

Last edited by MaczPayne; Jul 19, 2007 at 11:39 PM.
Old Jul 19, 2007 | 11:39 PM
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Originally Posted by RotaMan99
The amount of air, if any, that can get in the line is so small you don't have to worry. The OMP will pump that air out in a second or two. I have also had the check valve fail but have never ever had an issue.
My car stopped burning oil at the last oil change, it was working before, S4.

Thankfully I was premixing 4-6 oz just for insurance, I've bumped it up to 8oz a tank as I am no longer burning oil, which gives me close to a 250:1 ratio which I hear is about what the OMP gives.

As you say it is not the OMP that failed but it seems it was the injectors. I would get news one to replace them but I am planning on a TII swap in the future as it is so doing so seems a waste of time/money for me.


I would recommend to premix a little bit for insurance for if/ever you stop burning oil, as in my case.

Also I believe that S5s throw codes and put the car in limp mode if the OMP ever fails.
Old Jul 19, 2007 | 11:49 PM
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The E6K won't run it ... and I feel better knowing the premix is going into the engine. Cheap insurance.
Old Jul 20, 2007 | 07:39 AM
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My car stopped burning oil at the last oil change, it was working before, S4.

Thankfully I was premixing 4-6 oz just for insurance, I've bumped it up to 8oz a tank as I am no longer burning oil, which gives me close to a 250:1 ratio which I hear is about what the OMP gives.

As you say it is not the OMP that failed but it seems it was the injectors. I would get news one to replace them but I am planning on a TII swap in the future as it is so doing so seems a waste of time/money for me.


I would recommend to premix a little bit for insurance for if/ever you stop burning oil, as in my case.

Also I believe that S5s throw codes and put the car in limp mode if the OMP ever fails.
If your OMP was still working then your oil injector(s) were clogged. There is nothing in the injector to stop the flow of oil unless they were clogged.

And.......

I now keep my OMP but run a little bit of 2 stroke to help and incase the OMP does fail then I should be ok
Mechanical OMP? The OMP its self won't fail. Unless it clogs up or the injectors clog up which shouldn't happen if you stay up on your oil changes.
Old Jul 20, 2007 | 08:03 AM
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I pulled my omp, I buy 2 bottles of premix at a time and keep 2 bottles in my car at 1.59 a 16oz bottle thats not bad...

I run 1oz per 1gal..

my s4 omp was not flowing any oil.. so I pulled it and I am super happy.. I will do this with every car I own.. I dont have any problems with mess its cheap insurance etc..

The way I look at it is this.. if u have 2-3-4K into yoru engine and car but u cant afford a 1.59 bottle of premix which in theroy should last for 2 partial fillups then yoru being a cheap ***
Old Jul 20, 2007 | 08:39 AM
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Originally Posted by SpooledupRacing
The way I look at it is this.. if u have 2-3-4K into yoru engine and car but u cant afford a 1.59 bottle of premix which in theroy should last for 2 partial fillups then yoru being a cheap ***
lol thats true.

Originally Posted by RotaMan99
If your OMP was still working then your oil injector(s) were clogged. There is nothing in the injector to stop the flow of oil unless they were clogged.
if the filtered air line somehow got clogged it would definitely inhibit the injectors too, or even pinched for that matter.


the more i think about it the more it makes me wanna premix.
Old Jul 20, 2007 | 09:52 AM
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on my 89 vert one of the omp lines was broken but I park in grass so I never knew this... it took me about 3 months before I had it in the air and noticed the hole in the line...

if I had been premixing the engine would have been gaurenteed fine.. however now the car starts hard and runs a bit rough.. has since I got it and the line was broken since before I had it..

omp all the way
Old Jul 20, 2007 | 10:35 AM
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if the filtered air line somehow got clogged it would definitely inhibit the injectors too, or even pinched for that matter.
Ok now you are just trying to find any reason why the OMP system may not work and are starting to get paronid. How the hell would that line become clogged?

Besides, the check valve is not there to stop air from getting into the oil injector line. The check valve is there to stop the oil from flowing back through the vacuum spider.

You guys are talking paranoia. There is no way for the OMP or OIL INJECTORS to fail to the point where no oil will flow unless they become CLOGGED!

The Oil injector lines are plastic and if any of you were smart about how britol plastic gets when it gets old, you would replace them ASAP with new ones and not worry for the next 15 years.

Look in the Lubrication Section of the Training Service Manual here and stop being paranoid!
http://wombat.sevarg.net/RX7/RX-7_Tr...n%20System.pdf

If you feel you are 100% correct, which you are not along with the other guy that actually thought the check valve was to stop air from getting into the OMP line, then replace the injector with a standard banjo bolt. The only issue with this is that no air will be pulled through the injector to atomize the oil with the intake air so the lubrication will be deminished
Old Jul 20, 2007 | 10:37 AM
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Originally Posted by RotaMan99
A failing mechanical (series4) OMP is almost non existant. If its working, leave it alone. If you have the time and skills, convert it to 2 stroke but you won't gain anything from doing that unless you are putting in a new engine.

You can put a mechanical OMP on a S5. You just have swap the OMP COntorl arm from the S4 TB onto the S5 TB. The HowTo is in my sig.
one idea on the subject is that since the OMP pumps your filthy motor oil into the chambers, premixing can extend the life of your engine no matter what since you get nice clean oil in with the gas. I buy into that idea, it makes good sense.



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