Oh, and regarding the temp sensor in the dynamic chamber:



That's why you can unplug that sensor and drive around with no effects - it only corrects the BAC duty and seemingly nothing else.

 

What a great response!

While first going over all this information I was blinking thinking, it's so obvious, ( The vacuum source for the diaphragm comes off of the secondary throttle bores. )

This is one of the missing pieces I now have! The primary and secondary intake are completely separated!
So, selecting the secondary intake manifold for a vacuum source would change when the vacuum that the diaphragm receives. (just a summary.)

I'll need to go over it all, this is just the level I was looking for!

 

There's a ton of useful information in the training manual. It's available (free) at Foxed.ca along with the service manuals and a bunch of other documentation.

The Training Manual is underrated. The FSM is good and all, but given that FCs have a complicated EFI / emissions system, understanding what behaviour the car should be displaying under various conditions is a big help when troubleshooting. The FSM shows you how to test / replace parts, but doesn't really explain the rationale behind why everything works the way it does.

The only weird quirk with the training manual (that I mentioned before) is that the default NA they are showing looks like the EU model (with butterfly valves for the AUX ports and a single ignition coil). So the "Australia Only" model corresponds to the US / Canadian FCs for some reason.

 

I never knew a training manual existed until today! Thanks!
I will reference it going forward.

 

After going through the training manual, I found out what the double throttle does!

It is for preventing hesitation during acceleration when the engine is warming up. (Coolant below 140 degrees F).

It does this by gradually opening the #2 secondary throttle valves even if the #1 secondary throttle valves are suddenly opened!
This prevents a lean air/fuel mixture during rapid acceleration. (Hesitation)

So, if your diaphragm is leaking or you wire the valves open you will experience hesitation if you floor it while the engine is warming up.

One less thing to be worried about!

 

Hi everyone,
I finally got around to taking apart a diaphragm to see why they fail.


#2 secondary throttle diaphragm.
These need to be able to hold vacuum, if they don't hold vacuum, they are not functional!



Free height of spring, this shows that the internal spring is not under much tension.



Interior parts. There is the spring, and the rubber membrane attached to the arm.



Membrane and arm. This side of the membrane seems to be covered in a reinforced mesh layer!
Probably because this side is open to the outside atmosphere where debris can enter.



Vertical cut in membrane. This is the only faulty area on either side of the membrane.
The cracks that run at random directions do no go all the way through!
Only the vertical cut shows light through it but does not go through the reinforcement mesh!

I have concluded that the only part that would cause a vertical cut is the sharp cut end of the spring.

Does anyone know of a way to cleanly open and close the crimping on the housing!

I am going to try to seal the cut and cracks in the membrane using water thin cyanoacrylate glue.
This glue will be flowed onto both sides of the membrane using gravity to evenly coat them.
A few drops at a time, swirl them around a bit then let the glue dry overnight.
Then test to see if it holds vacuum. Once it does, I will apply another coating then install it onto the throttle body.

How long my fix will last is debatable, I would have to test it with my vacuum pump every two months to see if it holds up!

What do you think of my idea?