i have 89 gtu, i was wondering what the double throttle diapragm does, what it's for, and how does it exactly work? I'm asking because i don't kno if mine is working rite or not. if it does work, how high does the engine have to rev for it to work? any help will be appreciated. thanks.

 

it controls the 2ndary choke plates during cold temp operation so you dont over rev the engine when cold. the plates close when the engine is cold. Vacuum is applied to the diaphram controled by the water thermo valve on the back of the tb

Look at where the rod is when the engine is off. Then look at where the rod is when the engine is running cold. If the rod is in the same place, disocnnect the vacuum line to make sure there is vacuum. if not, check the water thermo valve to make sure is working properly.

 

I was under the impression that the plates were closed during low load operation to increase intake velocity, and then were opened as the velocity/load increased.

 

I think they're refering to the No.2 secondary throttle valves. The outer set. And talking about a non turbo RX.

They are spring loaded wide open on a non turbo. They close if the engine water temp is cold and gradually open as the water warms up.

If the diaphram in for the double throttle is busted, then they stay wide open all the time. Talking about the No.2, secondary outboard throttle plates, not the No.1 set of secondary throttle plates.

I think J-Rat is talking about the No.1 secondary throttle plates. The inboard ones.

I've never seen a working Double throttle diaphram. All my na cars had the No.2 secondary throttle plates wide open all the time.

If the thread owner wants to see if his non turbo diaphram is any good, just pull its vacuum hose off and with another piece of vacuum hose put it on the diaphram and see if the diaphram will hold a vacuum when you suck on it.

 

If you go to this site http://wombat.sevarg.net/RX7/RX-7_Training_Manuals/ and download the section called Fuel and Emissions, there is a section dedicated to explaining the double throttle sys.

 

How did you find those training manuals, Hailers? Awesome find.

 

thanks a lot u guys. I'm going to go check it right now. thanks again.

 

THANK NZ CONVERTIBLE for the manuals and SYNOK for the site to download them from. The section on the ECU is the fun one.

I misread this thread a little. The double throttle diaphram gets a source of vacuum when the engine/water is cold. The vacuum acts on the diaphram which pulls a lever and closes the seconday outer plates.

When the water warms up, the waterthermo valve closes and the source of vacuum is removed from the double throttle diaphram. Then the secondary throttle plates are spring loaded open. That's on a non turbo only. Turbo is different.

 

And, NZCONVERTIBLE wants others to mirror the manual. Sounds like YOU to me. Others are already doing it. Sorry, I don't remember names very well. Thanks to all for posting the manuals. Helps me. Should help others. At least those that don't know it all already.

 

Syonyk is the correct spelling. And it's very bizzare to see a link, and go "WTF, that's my server?" and then remember what I posted there. Yes, mirror the damn things!

As near as I can tell, the double throttle diaphram serves as a small vacuum leak in all FCs at this point. It did something productive at one point, but no longer. Even when it worked, all it did was keep people from whomping on the engine when it was cold.

-=Russ=-

 

Ok, they are now mirrored on my site (See sig).

I'll try to put the FSMs too in there one of these days.

Cheers.

 

I saw what some would call trivia in that ECU emissions section. It's been asked before on this forum why is the water hose attached to the side of the BAC. The answer in the manual you mirrored says it's there for anti icing purposes and for the coil in the BAC to have a constant temperature.

I think I've seen the anti ice as an answer in the past but not the constant temp for the BAC coil.

There's also a graph on the fuel injection during STARTING. That should get some attention. It shows the time the injector is on in MS for a given temperature and it's constant during starting. So you take that info.....think about the flooding on this forum..........and say *then why not cut down on the time in MS that the injector is on during start................OR how to make the ECU not know it is in the START mode thereby cutting down on the time the injectors are open during the start cycle.

I played around and by using a fuel cut switch and a digital meter with a Duty Cycle function, I see that during start with a warm engine the duty cycle is approx 16-17 ms.

If I depin pin 3B on the ECU, the ECU no longer knows that it is in start mode and the duty cycle is in the 4ms range. A lot less fuel during start than the standard 16-17 ms on a normal car.

There's a hitch though. The car will start if it has been warmed up but won't start is the engine is stone cold. Not enough fuel. Sorta no choke function or accelerator pump type action like that.

Just FYI.

 

And the geeks go to work...

I'm glad the training manual was able to be scanned & hosted. It's a wonderful source of information that many of us have been guessing about until now.

-=Russ=-

 

those Factory service manuals? if so you can find those on alot of sites. even mine wich has a link to where they are stored.

 

No, these are the factory TRAINING manuals. See my sig. They're more "This is how stuff works" instead of "This is how to fix stuff."

-=Russ=-

 

Ya those are nice i just looked at them after I was able to get them working. I like em.

My question is. Looks like they mainly deal with S4 rx7s. How about S5 rx7s?