Installing IAC Valve

[Lazzman]

When installing a new IAC valve do you have to re-set the Curb idle, Or is it just ok to disconect the battery and bolt on the new valve?

Thanks much.

 

[MONMIX]

it should just relearn on its own.

Plug and play is what I am saying.

 

[Lazzman]

Yes, that is what I thought but the new one is acting the same as the old one. Maybe I will try setting the curb idle just for the heck of it.

 

[spindlecone]

Yes, that is what I thought but the new one is acting the same as the old one. Maybe I will try setting the curb idle just for the heck of it.

How will you re-set the curb idle

 

[BrooklynBay]

There is a set screw that is like a stop screw for the throttle. It should be adjusted with an RPM gauge. Ford recommends an average idle of 750-850 RPMs, and OTC recommends 900 RPMs. These are the specifications on the 88. I don't know if your model is the same.

 

[spindlecone]

There is a set screw that is like a stop screw for the throttle. It should be adjusted with an RPM gauge. Ford recommends an average idle of 750-850 RPMs, and OTC recommends 900 RPMs. These are the specifications on the 88. I don't know if your model is the same.

DO NOT DICK with that adjustment,It would seem that it is an idle adjustment, I do not think it is, more info from those that know pls

 

[BrooklynBay]

It is better not to play around with it, but according to the OTC/Ford fuel injection repair manual, they do mention adjusting it. Most of the time, it's not necessary to adjust it. Maybe there is a vacuum leak, or something else that is throwing off the idle.

 

[spindlecone]

It is better not to play around with it, but according to the OTC/Ford fuel injection repair manual, they do mention adjusting it. Most of the time, it's not necessary to adjust it. Maybe there is a vacuum leak, or something else that is throwing off the idle.

It will adjust the idle,But only for a short time,used that adjustment to increase my idle from 650 to 750, all is well, drive it for an hr, is back to 650, I think a PCM correction, Dunno, always marked the adjusting screw, always end up turning it back to the orig position, not a clue as to what it is for or why it is there.

 

[dogfriend]

It will adjust the idle,But only for a short time,used that adjustment to increase my idle from 650 to 750, all is well, drive it for an hr, is back to 650, I think a PCM correction, Dunno, always marked the adjusting screw, always end up turning it back to the orig position, not a clue as to what it is for or why it is there.

I'm pretty sure that you are correct, the idle speed is set by the PCM and adjusting the throttle body will not have a lasting effect. The PCM adjusts the duty cycle of the IAC to try to maintain the idle speed. If it can't maintain the idle speed using the IAC, that means that the IAC is not working right or there is some other issue (fuel pressure, MAF, etc.)

 

[ExplorerDMB]

when your throttle is "closed" it really isn't fully closed. This adjustment keeps it from going totally closed which would be like sticking your hand over the throttle body. Idle is controlled by the IAC and computer.

-Drew

 

[Lazzman]

There are some articles on here about setting curb idle, which involves disconecting the valve and starting the engine, then adjusting idle witht the screw to 675rpm. Then you reset the computer and plug the vavle back in.

Sounds like a good way to re-set the idle. Don't have the link though.

 

[celly]

There are some articles on here about setting curb idle, which involves disconecting the valve and starting the engine, then adjusting idle witht the screw to 675rpm. Then you reset the computer and plug the vavle back in.

Sounds like a good way to re-set the idle. Don't have the link though.

I had to do that when I had the Ford Racing TB for a V8 4.6L on my '00 Sport (SOHC V6, still for sale btw). It came in the box with no adjustment. You pretty much nailed it on how it's done.

However, I disagree that you need to mess with it after an IAC install.

 

[aldive]

When I want to adjust idle speed, I do it via the PCM; reprogramiing the computer tune via SCT's Extreme Tune Software.

 

[DeathsArrow]

I noticed right after I did my IAC the engine was idling a little on the high side, but it's since come back to normal.

 

[BrooklynBay]

The computer just had to learn a new pattern of operation for the new part.

 

[azthermal1]

About how long does it take for the computer to learn after installing a new IAC valve? Installed mine last night.......

 

[Jefe]

Yes, the PCM controls the IAC, in turn controling idle speed. But the IAC can only do so much. With the IAC disconnected and engine warm it should idle around 500-600 rpm. You can adjust the idle screw to get it idling correctly. check for vacuum leaks first. Once you plug the IAC back in it should relearn, and idle at the PCM set speed.