IAC valve questions

[Turdle]

OK
I was pulling this adjuster plate Which SVO sent, I am now sending it on to Dreamr.
In the process, I decided to look real hard at my IAC valve.

In regards to this "issue" I am fighting

http://www.explorerforum.com/forums/showthread.php?t=167231&highlight=surge

I have a handle on the surging, however the idle hangs, as in when engine is revved, it hangs at about 1800 rpms for a few seconds, then settles back down--there is a video of this in above link

Ok it is a tuning issue.

On to a few thoughts and questions

I sprayed some electronics parts cleaner into my IAC valve-which of course has been replaced and replaced again, and questioned-

I noticed the valve inside rides on a shaft, which feels like it is on a diaphragm, rather than a spring. It also does not close all the way by itself.

I also experimented, thinking it was on backwards--nope, engine vacuum holds it open when reversed.
Does the vacuum hold it closed? ( when installed correctly)

Or
Is this a linear motor, with a variable polarity voltage operating in both directions?
See where I am going?

I am kicking myself for throwing my old one away--I would sure like to see one dissected-----

 

[BrooklynBay]

http://www.explorerforum.com/forums/showpost.php?p=1411250&postcount=9

 

[rangerwilly]

OK
I was pulling this adjuster plate Which SVO sent, I am now sending it on to Dreamr.
In the process, I decided to look real hard at my IAC valve.

In regards to this "issue" I am fighting

http://www.explorerforum.com/forums/showthread.php?t=167231&highlight=surge

I have a handle on the surging, however the idle hangs, as in when engine is revved, it hangs at about 1800 rpms for a few seconds, then settles back down--there is a video of this in above link

Ok it is a tuning issue.

On to a few thoughts and questions

I sprayed some electronics parts cleaner into my IAC valve-which of course has been replaced and replaced again, and questioned-

I noticed the valve inside rides on a shaft, which feels like it is on a diaphragm, rather than a spring. It also does not close all the way by itself.

I also experimented, thinking it was on backwards--nope, engine vacuum holds it open when reversed.
Does the vacuum hold it closed? ( when installed correctly)

Or
Is this a linear motor, with a variable polarity voltage operating in both directions?
See where I am going?

I am kicking myself for throwing my old one away--I would sure like to see one dissected-----

I took an IAC apart. You have to use a die grinder to cut small slots on the crimped circular section. I did not take pictures. Clean every part. Put back together. Tested and works like new. There are some very small holes (in the diaphrgm part) that were semi-plugged w/ soot, et al...

 

[matt98sport]

Common cause of that particular IAC failing, is too much backpressure. Take that how you will, but my customers usually report a plugged exhaust system causing exceptionally high carbon build up in the intake. My truck had the same problem, and at the advice of one of the local shops i supply, i changed my muffler, cleaned my IAC (countless times before) and this time it hasn't given me a problem yet and i have about 9500k's on the muffler now, still no problem. Before i did this, the iac would mess up nearly every fill up.

Just my thoughts.. Matt

 

[cgriffin_5139]

Common cause of that particular IAC failing, is too much backpressure. Take that how you will, but my customers usually report a plugged exhaust system causing exceptionally high carbon build up in the intake. My truck had the same problem, and at the advice of one of the local shops i supply, i changed my muffler, cleaned my IAC (countless times before) and this time it hasn't given me a problem yet and i have about 9500k's on the muffler now, still no problem. Before i did this, the iac would mess up nearly every fill up.

Just my thoughts.. Matt

So how does the carbon from the muffler back pressure get all the way to the upper intake manafold?

 

[flya727]

I have to ask, where do you find the IAC valve? I need to do a little cleaning it looks like!

Thanks,

Rick

 

[BrooklynBay]

The IAC is located on the top of the intake manifold just a little past the throttle body.

 

[34Ford]

So how does the carbon from the muffler back pressure get all the way to the upper intake manafold?

Im guessing the EGR valve.

 

[flya727]

Found It!

Thanks for the info. I took off the IAC and sprayed some carb cleaner all around the inside. Let it dry and re-installed. So far it fixed my idle problem, mine idled bad on initial start up until engine warmed up some.

I never have that luck, usualy it takes me to the 3rd, 4th part till I find the problem.

Rick