Idle Air Control Valve (IACV), Bypass (IAB), Fast Thermo (FITV), HOW DOES IT WORK!??
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Idle Air Control Valve (IACV), Bypass (IAB), Fast Thermo (FITV), HOW DOES IT WORK!??
Alrighty, now I've searched... and I've read every single thread about the IAB valve and how to check it. I've read how to clean the screen, and how to cover up holes on in the TB 1 at a time to test it.
Does anyone know EXACTLY how the IAB works and how to test it OUTSIDE of the car? Or tell me what range of voltages it is SUPPOSED to receive from the ECU? I'm going to take it out and check the wiring going to it to ensure it is being SENT the correct voltage range. With the IAB OUT OF THE CAR, I'm going to power it directly to also ensure it is mechanically functioning.
Can somebody tell me what voltage ranges are sent to this unit and what the unit will do under different voltages?
Does anyone know EXACTLY how the IAB works and how to test it OUTSIDE of the car? Or tell me what range of voltages it is SUPPOSED to receive from the ECU? I'm going to take it out and check the wiring going to it to ensure it is being SENT the correct voltage range. With the IAB OUT OF THE CAR, I'm going to power it directly to also ensure it is mechanically functioning.
Can somebody tell me what voltage ranges are sent to this unit and what the unit will do under different voltages?
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From: Saint Paul, MN, USA
Re: Idle Air Control Valve (IACV), Bypass (IAB), Fast Thermo (FITV), HOW DOES IT WORK!?? (Black-LS)
Well, I do know that the IAC is a stepper motor that moves in steps. If you look at a Scan Tool, it'll read - IAC xx counts...
What it does is moves into and out of the Throttle Body. It helps with fast idle on cold start ups. It moves into the Throttle Body and rpm drops and vice versa..
Maybe someone else can shine some light on this..
What it does is moves into and out of the Throttle Body. It helps with fast idle on cold start ups. It moves into the Throttle Body and rpm drops and vice versa..
Maybe someone else can shine some light on this..
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Re: Idle Air Control Valve (IACV), Bypass (IAB), Fast Thermo (FITV), HOW DOES IT WORK!?? (Black-LS)
Doh... I forgot to look at the Helm book... 
The IAB (secondary runners in the intake manifold) are pulled closed by vacuum, & the vacuum valve is either open or closed. No intermediate positions... Like almost all valves in the car, it gets +12v always from the main relay; when the ECU wants to open or close it, it closes the ground side of the circuit to the valve.
If you want to test the IAB off the car, I guess you've got the intake manifold sitting on a bench?? You want the vacuum line from the secondary valves, & the solenoid valve on the end of that line. On the other side of that solenoid valve, hook up a vacuum source (MityVac?) Jumper 12v to the plug on that solenoid valve & see which way it works. Energize the solenoid to open the valves vs. energize to close the valves (I don't remember which).
I haven't messed with my FITV, but I believe it's just operated by the coolant temperature. There's no wiring harness to it, so if you want to test it you have to use some hot water...
The IAB (secondary runners in the intake manifold) are pulled closed by vacuum, & the vacuum valve is either open or closed. No intermediate positions... Like almost all valves in the car, it gets +12v always from the main relay; when the ECU wants to open or close it, it closes the ground side of the circuit to the valve.
If you want to test the IAB off the car, I guess you've got the intake manifold sitting on a bench?? You want the vacuum line from the secondary valves, & the solenoid valve on the end of that line. On the other side of that solenoid valve, hook up a vacuum source (MityVac?) Jumper 12v to the plug on that solenoid valve & see which way it works. Energize the solenoid to open the valves vs. energize to close the valves (I don't remember which).
I haven't messed with my FITV, but I believe it's just operated by the coolant temperature. There's no wiring harness to it, so if you want to test it you have to use some hot water...
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