Just found this post from 2009!

Just figured out another bit of useful information I thought I'd pass along. The AC Delco part number for the IACV-Stepper Motors on '94 & '95 -DI's is:


Almost all mid 90's GM's have this part
AC Delco #217-437
NAPA part # CRB 21738 $47

 

in your pic that shiney nipple on the right is what gets cleaned and the hole it goes into in the plenum, if you turned it the iacv is going to be off

 

Cleaned it up good, no change. going to try a couple from my friends upull tomorrow, if that doesnt work then I'll fork up $50 for a chevy truck one.

 

got to the upull that my friend owns. He had 2 icav waiting on me. Installed them in parking lot. 1st one same results. 2nd one presto 725 rpm on the button. Drove to the gym, worked out, went out and cranked up, back to 1000 rpm again! Damn this thing is tempermental!

 

Tom what do you mean, if I turned it?

 

It turns , its on a screw that's how it moves in and out to meter the air

 

ok you mean the plunger looking pointed metal piece with the spring. No i didnt do anything but spray it w carb cleaner.

Weird how it went to correct rpm for 5 mile drive, then reverted back to 1100 again. I took the newer one out once I got home and cleaned that one too. Nothing. I guess I can try another used one. I hate to go buy a new one and not know for sure that is what is causing it.

 

Tried 6 different IACV's so far. None improved over about 900 rpm cold idle. Took air box off and sprayed some cleaner in MAF again just for giggles. Same. I don't think throwing a $50 new IACV at it is the answer either since none of the used ones made a difference. Noticed the two lines that run into the ram housing are dry rotted. I'll try that next.

 

I have a 96' 4.0 disco. I am currently having the issue of my idle hovering around 1200-1500 rpm on startup. When I put it in gear though, idle will always drop to normal and won't try to take off on me. I suspected my TPS was going bad. It is 18 years old. I removed the TPS, but left the connector plugged in and my idle will drop to 750, which is normal. I put the sensor back in while the engine was running and it will either stay at idle or search around a bit. I don't see a leaky vacuum line, but who knows. Right now I am set on TPS. Also, sometimes it will start at normal idle.


I just ordered a used one off an old RRC for 25 bucks on Ebay. Best deal I saw. There are others on there for much cheaper then 150 bucks. I figure I'll test my theory out for 25 bucks.

 

Let us know if that fixes it. I just learned to live with it. Mine will idle at 1200-1550 but drop to 900 in gear so I just said well if thats the worst thing that can happen Im happy!