Around 6 weeks ago I had major crash on oil injector theory and unfortunately everyone look at them a simple nozzle.
Based on service manuals and my tests I made my conclusion and colour this pages.
My initial take was that the oil injector works like power valve carburettor, where the air works as brake to prevents over flow.

However, I wasn't totally satisfied till I cut one open and make this pics last night. ( yes I do have OCD, by product of technical work is OCD)
Note on pics are note to my future self











Normal flow





air inlet






back flow





wrong

 

Nobody looks at them as a simple nozzle. Rather, you keep assuming nobody but yourself has any idea what goes on in this engine. Which all that is explained in various technical documents. And now you proved it for yourself that the documents from Mazda are accurate. Congratulations. That’s why they have a test to ensure whether it’s working properly or not.

Otherwise you should get OCD on improving your English grammar and word skills because your comments are difficult to follow, if not completely incomprehensible. That’s not an insult or criticism. You might actually be a pretty smart guy, but nobody can make heads or tails what it is you’re trying to say. I have the same problem with my Japanese skill.

 

Mazda test is very simple Black and White, put this much xxx Hg/mm vacuum for that xx time, If it doesn't hold, then replace.
No word for cleaning nor how its works.


The reason I dig it this deep is lack of info about them, I searched this very forum to sub-cellular level and any other places.
only one guy on youtube opening them and two other person DYI barb part to be "cleanable" .

I didn't explain it in this topic and just drop pics here, as the parameters are unchangeable.
Beside, it has simple and effective design.
as far I can understand two changes would improve them.
1- adding longer house and moving collector away from oil injectors
2- adding quality ball check valve to each injector air feed to separate air pulses
Thanks for advice My English is IELTS academic 7.0 however, I believe it would never becomes like my mother tongue as my Hungarian never did.


So far I manage to move air collector away and used equal length houses.
Perviously, on test both front rotor injectors failed on holding vacuum and changed to S2.

 

you’re adding check valves to the check valves, you’re head isn’t on straight

this is classic mad scientist 101; you’re magnifying and elevating cause & effect in your head way beyond the actual reality and not accomplishing anything useful imo

 

It is not 2+2=4 to say there is one check valve other would do nothing. Ball in check valve is heavier than diaphragm and have
differs frequency of work.

If additional check valve site way after air feed line, it would even worsen it, as it would increase dead space( vacuum volume).
So far I am happy with my setup as it feeds sohn clean oil to OMP .
One last thing the dirty oil wont cause air leak injector as far I can say, the diaphragm would lose its flexibility. Further more if you try to
clean injectors with harsh/ corrosive chemical it would dry out rubber diaphragm and make it worsen for future, only thing I might give shot is ATF or liquid paraffin in situ.
Those they made serviceable injectors failed big time

 

it makes you feel good, but in reality you have no clue about the value of your efforts. The same goes for the Sohn device. There’s not one lick of proof it adds any value or that the engine lasts any longer. Just opinionated feel-good fluff.

 

Derp. And Team is right about the SOHN adapter.

 

And further, there is not a lick of proof that it has no benefits. Or does damage in some way. Let’s give a complete thought since we are talking about “proof”.

nobody yet has been able to clearly explain why there would be no benefit.

it’s always “ There’s no proof” etc, but not any coherent reasoning as to why not.

So, into this void of information, and this cornucopia of opinion, I will state my opinion:

The sohn allows a greater quantity of 2 stroke oil to be injected if the owner dials up the omp settings.

It is proven that 2 stroke oil burns better than 4 stroke in a combustion chamber. It is designed to.

if you choose to inject more oil, it then follows that 2 stroke oil will be better to inject
than 4 stroke, if only for deposit control. But there could be better lubrication as well, especially with greater quantity.

Injection has historically been better to use in total loss engines, than simple premix, because it is able to deliver a wider range of oil quantity based on load, and deliver more oil to the correct areas in the chamber. Premix takes more oil for the same results, and is a fixed fraction, so it is optimized for only a small sized load characteristic, and sub optimal everywhere else. The owner can set omp tables to advantage at any load really.
But even with greatly enhanced omp output, premix is still advised in my opinion, since the factory set up may not give adequate lubricant in certain areas. It is important also to remember lubricant is a coolant also.

Dirty oil has less lubricity in the stock quantity omp settings, since the amount is so minimal, any solids or non-oil liquids would further impede already marginal lubrication, in my opinion.

So again, it’s true no one can prove the Sohn has benefits, but it’s also true those who chime in likewise cannot prove it doesn’t.

Plus, there is no argument against using the sohn, that makes as much sense as using it, in my view. Most arguments against are weak compared to those in favor of.

While it is true to state there is no proof the sohn works, that is not the whole story at all, but usually it ends there on this forum. It shouldn’t in my view. Again, there is no proof it doesn’t work, and there is no quality statement of theories as to why it wouldn’t work. Conversely, there are reasons to believe there is benefit especially when combined with omp output recalibration.

 

Mazda recommend 0W-20
I am using sohn because it just let me to pure full synthetic 10W-60 in engine "safely".
In my book OMP system design needs low viscosity 0W-something and have problem with 10~ 15W-otherthing,
so in conclusion people have to use heavier oil to save bearings or use lighter oil to save apex seals, and mostly chose former.
Currently with 10W-60 and 43,000 mile on clock, baked hot engine lowest oil pressure is 1 bar, tab on oil sandwich.

 

 

I dunno what type fo crack you smock but change your dealer ;d

 

Heisen, I'm a rank amateur mechanic compared to the other guys on this topic, but I'm with Team on the check valve stuff. I don't believe the engines are failing due to lack of a 2nd check valve with different ball check specs, nor do I think the oil injectors are an inherently faulty design. Test them, if operating correctly you are all set, if not clean or replace.

Kevin, good set of comments on Sohn. As I was saying in B@W thread I'm thinking about adding a Sohn, but need to check my injectors out first.

If this engine was being engineered in 2020 I'm thinking a different oil injection method might be used, can picture actual injectors that are computer controlled by load and rpm. But it was engineered quite a few years ago at this point.

 

Devil is detail like any other complex system, I am not here to spoon feeding, those pics are great cheating note.
Cleaning will cause failure, I did experiment over 4 sets of injectors, total 16. subject from S1 and S2.
Initially leaky injectors showed 80% improvement after cleaning, holding vacuum way over few min suggested Mazda.
So far so good ? nope as soon as they went thought working cycle they start to fail. all of them
You think they didn't clean up enough ? wrong, I open them they where as clean as waxed crunch of Swedish model. problem is with
elastic diaphragm material.
When they fail they must be replaced no cleaning or opening can treat them, there is no permanently remedy.

 

My thoughts ...FWIW . For those that change their oil regularly ...there is no measurable benefit in using the Sohn. Where we see premature wear in the housings is as a result of poor oil change habits combined with inner city (grandma) driving ....................... IE contaminated oil getting confined to the areas around the injectors due to low rpm/low throttle operation.

 

I have had no issues cleaning the check valves either. If you use an ultrasonic with A rubber friendly solvent you will have good results.. just don't let your DA catch you with them in the one at work 😁

 

.

 

It not about cleaning, the elastic diaphragm fails. I don't have acc to part numbers, but based on my personal tests they changed some thing about spring and/or elastic diaphragm on s2.

My recommendation is to re-test oil injectors after they worked for while and cycled.