NEW PARTIAL Rat's nest removal mod...
 

Things to keep in mind:

1. I'm far away from my car right now so all of this info has been sources and constructed from forum info/ Mazda FSM's...(Being deployied in Afganistan leaves me lots of time to think about what I'm gonna to do my 85 12A R-x7)
2. This setup assumes the user will install a header or bypass the catilytic convertors some other how...
3. This setup also assume an aftermarket air cleaner is installed.(Hance the need for breathers)
4. Please provide feedback so I can perfect it and in 2 months when I get back to AK I will do it...
Purpose: To delete uneeded emissions items and keep those the promte MPG. This is intended to be a hybrid setup between full rats net and full without.
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THis first Image is a diagram of the current no emissions config(Carl and Matts idea):
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The second image is the proposed idea:
1. Allow the computer to control timing which will boost MPG
2. Allow the stutter valve to remain since mazda claims it increases MPG by 20%
3. I'm not sure if the stutter valve will work corretly without #2 AAB so it stays also(More Research Pending)
4. All other emissions items removed(CATS, ACV, Airpump, RELIEF Valve, Switching Valve... )
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The Third image is the proposed idea: if the shutter valve will work without AAB #2 the just plug the stutter valve in to manifold air of any kind. Since I'm not in front of my car to find out if the removed items are manifold air(RELIEF Valve/Switching Valve) I'll need someone to do the research form me.

There is no "computer" that runs timing on an FB. It is done within the distributor via vacuum and weights. Keeping the timing stock with the vacuum advance hooked up to the stock position will provide the best fuel economy.

Can't really comment on the shutter valve hypothesis.

Not in the sense of a modern fuel injected car would, but in the sense that it can cut advance during deceleration

In another thread I read that with the soliniods
"At idle, there is no vacuum present.
At 1000-1200 RPM, the leading vacuum solenoid opens applying leading vacuum advance.
At 2900-3100 RPM, the trailing vacuum solenoid opens applying trailing vacuum advance.
If throttle is released past 4000 RPM, both trailing and leading vacuum advance is cut.
"

UPDATE: I have attached 1981 tech data which explains mazda's original intent

So basically, Vacuum advance could be hooked up to port air, as mazda does for CA emssions models.
But the computer control part is that Vacuum advance is cut when cold or with the choke on in any tempature. Base timming without advance would be better when cold...

Interesting project. I can attest to the fact that with a stripped rat's nest, best performance is with ported vacuum to the advance (although I run leading/trailing advance together).

Keep up the good work man. :)


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The diagram on the far right looks correct.

Update
 

update: I have determined that #2 Anti Afterburn valve is not require for shutter valve operation... THe coast and shutter valve work with each other and #2 AAB has to be closed to allow the shutter valve to work with the original config...

ok i want in on this
 

so very interesting this would seem to be the best for fuel economy and performance if u need any help just ask man if u need pics or anything i have a 83 gsl and am very tempted to remove the the rats nest but wanted the shutter valve function

can you follow the rats nest and tell me which port the yellow and soliniod connects to so I can be sure I have the diagam is correct...

ok, Ive figured it out... Here is a new diagram

Cool idea, looks awesome. I will keep tabs on the thread until I see it has come to fruition. I actually just bought the silicon hose to redo my rats nest in all blue - I like the custom look under the air cleaner with the blue hose, and I want it back on the car. Not trying to start the debate, there are plenty of other threads for that.