Curiosity Question

[fivespeed3.0]

Under Wide Open Throttle conditions, does the IAC solenoid fully open as well? I'm asking about a 2000 3.0. Just curious.

Thanks

 

[Big Jim M]

Not me!!

Under Wide Open Throttle conditions, does the IAC solenoid fully open as well? I'm asking about a 2000 3.0. Just curious.

Thanks

I don't know for sure. BUT on a carbed engine the fuel delivery DEPENDS on that small amount of fuel from the idle jets.
My guess is that when opened, the butterfly directs incoming air away from the idle port and the idle system stops working in a fuel injected engine. I don't know for sure but I'd think that is what happens.
Big JIm

 

[RollinWOT]

I assume it wouldn't because the IAC is essentially a computer controlled vacuum leak in it's most simple form. I don't think it would, in fact it would probably close most of the way because air would be going into the throttle body most, and not the IAC.

 

[99RangerBoss]

i believe i read somewhere that you A/C clutch disengages and your IAC fully opens

 

[Rearanger]

My understanding is the IAC bypasses the throttle plate when the throttle plate is closed so the computer can more accurately control idle speed as well as emissions when the throttle plate is closed abruptly as in de-accel. Before there was an IAC there used to be a dash pot that closed the throttle plate gently to set idle position. The flow through the IAC still would pass through the MAF - I would guess. The TPS has a set-up adjustment to send a signal to the ECM when the throttle plate is just open (off idle), sooooo, I would say, without first hand knowledge, the IAC is closed when off idle, including WOT. But, it may be easier to handle the operating smoothness of crossover from idle to throttle plate and back, to just leave the IAC open. Hmmmmm?

 

[fivespeed3.0]

In my mind, it would be logical for the IAC to be fully open when at WOT, giving that extra little bit to support the fact that you are demanding all she's got at WOT. The extra incoming charge from the IAC would still be measured by the MAF. I also have read somewhere that the A/C clutch gets disengaged at WOT. This also supports the notion that if you are at WOT, you are demanding all she's got, and the A/C, when on, is a power draw.

Does this sound logical???

 

[JP02XLT]

My understanding is the IAC bypasses the throttle plate when the throttle plate is closed so the computer can more accurately control idle speed as well as emissions when the throttle plate is closed abruptly as in de-accel. Before there was an IAC there used to be a dash pot that closed the throttle plate gently to set idle position. The flow through the IAC still would pass through the MAF - I would guess. The TPS has a set-up adjustment to send a signal to the ECM when the throttle plate is just open (off idle), sooooo, I would say, without first hand knowledge, the IAC is closed when off idle, including WOT. But, it may be easier to handle the operating smoothness of crossover from idle to throttle plate and back, to just leave the IAC open. Hmmmmm?

Rearanger, I think you description is spot on, with the exception that I do not believe the IAC fully closes, I think it returns to or very near the last previously know idle position, then if needed makes another adjustment as the throttle closes, the reason is, if you just crack the throttle really fast there would not be enough time to allow the IAC motor to fully close then open again for anywhere near a correct idle speed, so I think it goes to a last reference point. I have seen IAC count numbers fluctuate on a scanner reading real-time data that tends to support this. It would be a worse situation if the IAC went to full open on WOT, not anywhere near sufficient time to return for proper idle. I know on my ranger all the air flow passes through the MAF 1st so the IAC circuit uses the data on idle as well. As for killing the AC on WOT, some vehicles do & some do not, cant say I have ever tried it on the Ranger.

JP02XLT

 

[Rearanger]

Does this sound logical???

I wonder if you could check this by disconnecting the intake from the air filter to the throttle to allow access to the IAC inlet. With key off use a little compressed air put into the IAC inlet and see if you can feel flow at it's outlet to confirm closed position. Then turn the key to ignition on (no start) and use the compressed air again to test for flow through what should be open idle position of IAC. Then have someone depress the gas pedal to open the throttle plate to various positions and see if you get continued air flow through the IAC. This may not work if the ECM needs to sense flow through the MAF to initiate this process. On a 2000 A/T I would think the A/C compressor would turn off at WOT.

 

[JP02XLT]

That sounds like a good test procedure, especially if you can feel the presence at the outlet

JP02XLT

 

[Rearanger]

This may not work if the ECM needs to sense flow

Now I would think ECM would need to sense RPM not air flow?? But anyway, maybe worth a try.