I did the search and came up empty.

Here is the gig...2000 Expy 4.6 with 220k miles.
Cleaned the TB and EGR ports and it runs nice and smooth, but.... It idles high on start up and comes down slow. So I said "self you got a sticly IAC". Bought a new one and it still idles high but now I have a howl in the intake tube .

The EGR passes the suck test, so I don't think that is the source of the noise. When I put a stethascope to all the suspect parts it sounds like the noise is comming from the DPFE, is that even possible?

Did I maybe just get a junk IAC?

Need a little help here cuz it's Mama's car, and when Mama aint happy-nobody is happy.

Thanks in advanced, Jim

 

Round 2

Put the old IAC back on and the noise is gone, but I still have the high idle and slow to come down.

BTW it idles about 1000 in park and about 1500-1800 on start up. It takes about a 10 to 15 count for it to come down.

 

Sounds like the new IAC may also not be closing/opening all the way. Stuck partially open or would make a howling noise I would imagine. Or the diaphragm is not sealing all the way. I would take it back since it is making noise and see what another IAC does. Mine, on cold cold starts takes about 10 second to come down from 1000-1100ish. On semi cold starts (sitting for an hour or so) it only takes about 4-5 seconds to drop down to idle speed.

Does the plunger in the IAC move freely on the new one compared to the old?

 

Yes, the plunger does move smoother on the new one. The thing is, it is open just a tad. I thought that the plunger should be all the way closed until it gets an electrical signal....But what do I know, I have a growling truck!

Thanks for the reply Toyz.

 

Is the IAC horn still in place? IE, -black box.

 

Yes it is. Completely box stock except for the K&N Air filter (came with the truck).

I took the "new" IAC back and exchanged it for another one, and all seems to be well. It dropped about 50 to 150 RPM's at idle in park and the RPM's seem to come back down quicker now.

The only other thing that it might need is the elbow that comes out of the lower port on the "black box", just haven't looked too hard for another one. No codes and it runs well for 220k miles!

BTW the IAC was from Auto Zone......I know, I know

Thanks for checking jbrew.