ok electronics question here..

[black34v6]

i mean this seems like the right place for this, but i could be wrong.

here goes:

is the IAC (Idle Air Control) Valve a Resistance based sensor, or a Voltage based sensor?

discuss..heheh..
actually i just need to know for a project..if i can get it to work ill take pics and shove it up here for everyone to see ;) its 3.4L only unfortunately..but i could use any help that is offered [img]smile.gif[/img]

thanks.

-R

[predator5100]

Dealing with electronics for many year you more than liekly have a resistance based sensor most senseors consist of resistance for the fact voltage can be very hard to control without a zenior diode and a sorce of steady power and a stabilizer circuit. However not knowing electronics on cars only aircraft and well other things it';s hard sayign the ones on the aircraft are made up of two strands of metal material. One has a constint variable and the other adjust with heat to match this in return tells the compouter how much air is going in for it takes a ceartain amount of air to cool this starnbd i serioulsy doubt yours in the car are nothing more than a resistor just liek the diode in the key for your igntion

[black34v6]

umm...so i guess you are saying that you dont think its just a resistor?

it only has two wires going to it...

-R

(digs around for picture of the thing)

[Tiago]

I think he said he thinks its a resistor based sensor, I agree.

[TurboProject]

the IAC isn't a sensor at all. It's function is a valve. Inside the round case is a stepper motor controlled by a motor controller in the computer. The pendel attatched moves in and out of the throttle body to increase or decrease incoming air to control idle speed. It is probably diagnosed when the computer sends a signal to this stepper motor, it sees different MAP sensor signal as well as rpm change. I'm guessing on the diagnosis part, but I know it is just a stepper motor. But all the stuff about the sensors seems exactly right and is definatly educational to me. ;) So what are you planning?

[TurboProject]

Doh, I just saw you said it only has two wires going to it...the IAC valve has 4 wires. Are you talking about the intake air temp sensor? If that is, then yes, just like the man said, it is a thermistor, w/ a material inbtwn two electrodes that changes resistence with different temps. The computer sees it as a voltage change, a change from the voltage it supplys to the circuit. Good old ohms law...
If you're not talking about this either then I'm totally lost [img]tongue.gif[/img]

[black34v6]

i can admit it if im wrong.

this is a 1994 3.4L V6 Chevy Camaro..
so the 3.4L OHV engine.

i am talking of the little black solenoid attached to the side of the 3.4L Throttle Body. If i remember right it only has two wires to it...i could be wrong however. i am NOT speaking of the tube plugged into the rubber elbow.

anyway. right now i am looking for a way to:

have the ECM send a signal to one IAC, and when it reaches the one, it also gets sent to another at the same time, then the two convert it back to one signal and send it to the ECM. is it possible to do this simply..without a major degree in electronics? im hoping so. i was thinking that if its a resistor type system..then just add a resistor to one side so that each IAC thinks it is the only one..thats if its hooked in parallel..i could be totally off on this tho..

-R

[TurboProject]

I'm pretty sure it has 4 wires. I have the book infront of me and it has 4 wires, two going to two different coils in the IAC motor. Light lue/white is the "hi" of coil A and light Blue/black is the "low" of A. Light Green/white is the "hi" of B and light Green/black is the "low" side of coil B. I'm pretty sure there is a complicated way that the computer controls this motor, and being as I dropped out of the electrical engineering degree I was persuing I can't help you there. The only other thing on the throttle body is the TPS sensor which has three wires and it is a variable resistor which is powered by + 5 volts from the computer(which is one wire) and then there is a ground wire, and the last wire moves w/ the throttle plates and the computer sees the resistance change on that last wire. Hope this helps you w/ your indevor, I'm not trying to throw information in your face, just don't want you to make any mistakes that might harm anything.

[black34v6]

nutz. :(

4 wires eh? crap crap crap.

maybe i could just hook them in parallel?

i mean if its 4-wire, its probably just a voltage type sensor..in which case i could parallel them and it should be fine? yes no?

-$

[TurboProject]

From the looks of the diagram it looks like two wires power the motor windings to move it one way and the other two move it the other way. It's not a sensor, it's an actuator that puts more air into the intake at idle. It doesn't sence anything. The only thing the computer may know about it is the position the motor is in, but that's only for the sake of controlling it. Motor controllers count the revolutions of this electric motor to be able to tell how far it is in or out so it knows which way to move to get the desired responce. What are you trying to do? Why do you want to connect two of them? I'm guessing you could just splice off the wires in the same order to be able to have the 2nd IAC move in just the same manner the other one does. Or you could reverse some wires so one goes in and the other goes out. But then you might get into power problems since the current used to drive the motors would be halfed since you have two of them using the same power and they might not work as well. Is that what you want to do? Connect two IAC valves at one time?

[94-3.4]

So what do you plan to accomplish by doing this?

[black34v6]

you will all just have to wait and see ;)

dont worry. when i get it done ill post pics and stuff. [img]smile.gif[/img]

-R

[MidLifeSpeed]

Yeah ... the IAC valve is a stepper motor. There are two coils that are actuated in a specific sequence. The drive for these coils are voltage pulses, and they occur in a specific sequence. Adding another IAC in parallel with the stock one will cut the coil resistance that the drive circuit in the PCM see's in half and increase the required current by more than twice the stock requirements (remember it's a coil !). The timing of the pulses and duty cycles would need to be adjusted for the new coil impedances or the "stepping" action would not occur properly on either IAC.

You run the additional risk of blowing the drive circuits in the PCM (typically MOSFET drivers) as well .... PCM ==> $1500 ??? [img]graemlins/crybaby.gif[/img] as they are likely not designed with that kind of margin in mind.