IDLE SPEED VALVE, CLOSED Options

[timdog1720]

Quick question I know the idle speed is suppose to regulate the air flow when throttle is closed, But does it stays somewhat partially open when boosting?
in other words when I take the hose off from the air filter and place my finger near it to feel for vacuum during idle , I get a good vacuum... NOW when I rev the car I'm thinking I should get some kind of boost ooooor nothing ... for me it maintains a vacuum even rev it to 5000rpm.

i ask this cause I want to know if this serves as some sort of boost leak cause technically when the throttle is open and pressurizing the system, if the idle air control stays somewhat open wouldn't it just leak out through the valve back to the turbo which would seem like a leak?....

Please help me out on this one one and a half year going and still trying too figure out why my car is dumping super amounts of fuel.....

Thanks always guys

[Box]

Dumping lots of fuel could be either a ruptured diaphragm in the fuel pressure regulator, stuck open injectors, or possibly heavily fouled O2 sensors telling the ECU it's running lean and therefore enriching the mixture. Those are just some things off the top of my mind.

There is a way to test the operation of the IAC. Here it be: http://www.autozone.com/autozone/repairgui...900c15280074e35

About midway down the page for the 5S-FE.

[timdog1720]

Dumping lots of fuel could be either a ruptured diaphragm in the fuel pressure regulator, stuck open injectors, or possibly heavily fouled O2 sensors telling the ECU it's running lean and therefore enriching the mixture. Those are just some things off the top of my mind.

There is a way to test the operation of the IAC. Here it be: http://www.autozone.com/autozone/repairgui...900c15280074e35

About midway down the page for the 5S-FE.

yea butttt, fuel pressure regulater new installed, new fuel injectors (all 4), and its a 3sgte

[lagos]

Quick question I know the idle speed is suppose to regulate the air flow when throttle is closed, But does it stays somewhat partially open when boosting?
in other words when I take the hose off from the air filter and place my finger near it to feel for vacuum during idle , I get a good vacuum... NOW when I rev the car I'm thinking I should get some kind of boost ooooor nothing ... for me it maintains a vacuum even rev it to 5000rpm.

i ask this cause I want to know if this serves as some sort of boost leak cause technically when the throttle is open and pressurizing the system, if the idle air control stays somewhat open wouldn't it just leak out through the valve back to the turbo which would seem like a leak?....

Please help me out on this one one and a half year going and still trying too figure out why my car is dumping super amounts of fuel.....

Thanks always guys

I just got done taking mine apart and cleaning it due to a boost leak issue, and here is what I learned.

The valve can create a boost leak, but only through the valve to throttle body gasket or the back of the screws that cover the plastic housing. Mine was leaking boost there so I replaced the gasket and put rtv on the back on the screws to seal all that up and it fixed the problem.

As for the operation of the valve, there are 3 wires that go to the valve. The middle wire gets 12v. If you supply a ground to one of the other wires it will either fully open or fully close. My understanding is that once the ecu sees boost, it supplies ground to the correct wire and closes the valve.

Now it is possible that yours is not working correctly due to carbon build up. It might be worthwhile to take the valve apart, clean everything with carb cleaner and reassemble with a new gasket and rtv around the bolt holes that I mentioned.

[Box]

Ahh, ok. I just went to your profile and saw it was a GT, sorry. Testing procedure should be similar though I'd imagine, since they're both S series engines. I'll try and find out for sure though.

[lagos]

Those same instructions for the autozone link apply to the 3sgte and are exactly what I did. I think the valve is the same part number for a lot of toyotas as well.

This post has been edited by lagos: Sep 5, 2012 - 9:14 PM

[timdog1720]

Those same instructions for the autozone link apply to the 3sgte and are exactly what I did. I think the valve is the same part number for a lot of toyotas as well.

I did that yesterday cleaning the throttle body and the idle air got a good seal on everything ... but when turn the car on, not started it seems as if the valve closes if you try blowing threw the hose however starting the car i was saying if you place your finger during idle there's a good vacuum but if you rev the engine it maintains the vacuum threw the hose i was figuring that the IACV would close completely when throttle opens so it doesn't leak

[lagos]

Those same instructions for the autozone link apply to the 3sgte and are exactly what I did. I think the valve is the same part number for a lot of toyotas as well.

I did that yesterday cleaning the throttle body and the idle air got a good seal on everything ... but when turn the car on, not started it seems as if the valve closes if you try blowing threw the hose however starting the car i was saying if you place your finger during idle there's a good vacuum but if you rev the engine it maintains the vacuum threw the hose i was figuring that the IACV would close completely when throttle opens so it doesn't leak

I think it only fully closes when the ecu sees boost. Only real way to know for sure is to run a long hoes into the cabin and see what its doing under boost.

[timdog1720]

yea i guess just wanted to know if it fully closes when revving

This post has been edited by timdog1720: Sep 5, 2012 - 9:42 PM

[timdog1720]

ok wait another quick question where should the idle air control line go to ... from what section on the fmic line should it be getting its air from

[delusionz]

I posted something about this before with pictures

There will be an ever slight boost leak through there, if you pull it apart and see what its made of, you'll see that the valve has no way of sealing (two metal surfaces) only just by ultra tight clearances, so if any oil/grit/gunk is stuck in there, the valve wont operate properly.

yes, i was able to blow through it while holding the door completely shut even after cleaning it, so what I did was put a large one way valve to go back to my air filter pipe.

this small leak wont matter if its securely attached to a pressurized part of your system, but i have mine going back to the non pressurized part, hence the one way valve.


taking air from the pressurized pipes isnt a bad thing, it can be a good thing,

would make less tututututututu on throttle liftoff

AC idleup takes air from pressurised pipes...

[timdog1720]

I posted something about this before with pictures

There will be an ever slight boost leak through there, if you pull it apart and see what its made of, you'll see that the valve has no way of sealing (two metal surfaces) only just by ultra tight clearances, so if any oil/grit/gunk is stuck in there, the valve wont operate properly.

yes, i was able to blow through it while holding the door completely shut even after cleaning it, so what I did was put a large one way valve to go back to my air filter pipe.

this small leak wont matter if its securely attached to a pressurized part of your system, but i have mine going back to the non pressurized part, hence the one way valve.


taking air from the pressurized pipes isnt a bad thing, it can be a good thing,

would make less tututututututu on throttle liftoff

AC idleup takes air from pressurised pipes...

ok kewl