I decided to try to solve my high idle problem today after an unusually difficult short throw shifter installation.

When I gave up and went to put the intake back on, I bumped this green thing which opened up.



I could not find ONE mention of it in my Haynes manual. So I checked the online manuals through the FAQ and I think its a vacuum delay valve.

Is this going to be a pain in the *** to find a replacement for, or would somewhere like an Advance or Autozone have this?

Could this be the cause of my high idle (2000-2500 rpm)?

 

That's just a check valve for that particular vacuum line. The diaphragm that it runs to is supposed to open the outer set of secondary throttle plates gradually when you mash the throttle. The thing is, they're almost always broken anyway. It's supposed to keep the plates closed if vacuum is not applied, and I can see yours are open.

This is not going to affect your idle at all. The only thing you may feel is a little bit of bogging if you open the throttle too quickly. I never really did though. Just for reference, this is almost the same thing as the "throttle body mod" people talk about. Except there, the outer plates are removed.

If your idle speed is too high, check throttle cable tension and tighten the air bypass screw a bit (top of the TB under a blind cap).

 

If the valve is split enough, it will affect idle as a vacuum leak. If you need a replacement, PM me.

 

Mine also has the same broke piece. I have notices when you mash the throttle, it does bog. But I also notie a lack of power. It accelerates very slowly. Could this broke piece casue that problem. I am guess not, but I figured I'd ask.

 

The check valve is just there so the diaphragm only sees vacuum. It is not responsible for the movement of the secondary throttle plates. If it's broken, remove it and stick in a solid hose for the time being. If the plates are open by default like in the OP's picture, then the diaphragm has failed anyway, so it's not going to make a bit of difference.

 

I thought it has a spring that makes it open up, but with a vacuum on the tube, it closes until the rmps raise up. Am I incorrect in this assumption?

 

Sorry, I should restate that. I said it backwards in my first post. If the plates are open while the motor is idling (you won't be able to see the plates, but you can see the actuator arm), then the actuator has failed. With vacuum applied, the plates should be closed. When the engine is put under load, manifold pressure will reach atmospheric pressure, and the plates will open. You can also test yours by sticking a vacuum hand pump on it and watching for movement.

It's really a bad activation method though since it seems to fail so easily. The S5s and jspec throttle bodies use better methods.

 

Ahh... I see. Ya they are pretty brittle if they haven't been changed.

 

Ok, I was fiddling around with this. I don't know what its called, and yes I've looked in the manuals. I see it in the diagrams, but it doesn't label it.

When I push as indicated by the red arrow (counter-clockwise), my revs increase. When I push as indicated by the green arrows simultaneously (clockwise), my revs drop. It takes a lot more effort to twist clockwise, than counter-clockwise.

When I do twist it clockwise, my revs sit at 750 just like they should.





I guess my question is Is this normal? If not, how can I get the thing to go "back to zero", so to speak?

 

http://mazdarx7.iougs.com/index.shtml You should read that page. It really helps out. It explains all th diaphrams and what the do.

 

Amgine, that opens/closes the primary throttle plate. Turning clockwise is the same thing as pressing the gas pedal.

 

Ok. Should it be able to turn the other way? Because it does, and when it does, my revs go to where they need to be.

 

The plastic cap is there for a reason, to not mess with it. That's what sets the TPS. Since you've most likely changed it, download the FSM from sig line and set the TPS correctly.
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Yes, you can move it a tiny bit the other way, but what you're doing is causing the throttle cable to bind up a little. The effect will go away once you step on the gas pedal or rotate the assembly clockwise by hand. If the throttle cable is too tight however, you can loosen it a bit and you may get the idle speed where you want it. You should jumper the initial set coupler (green plug by leading coil) before doing this to be sure the ECU doesn't try to correct with BAC air.

I thought that too at first, but it looks like he just meant that he was rotating the throttle open. That's the first time I've seen the TPS screw with a plastic cap on it too. I guess it's commonly lost/thrown away.

 

Yeah, I just meant opening the throttle. And also closing it more than it sits normally.

Although, I think I might have rotated the TPS a bit, too.

 

It is in your Haynes. Page 227. Fig 13.87 shows it as a delay valve. Also on page 277 fig 13.111 and fig 13.113.