Iac Valve Question

[Johnatthebox]

The iac valve in my bbk throtlebody is whistling loudly and my idle is really high. I actually have been driving around like this for a long time( I thought the BBK just sounded like that....lol) . Someone finally clued me into this. My question is this:
Is there a big difference in the assortment of gm tpi iac valves? Some are 20$ and some up to 150$ but they all look the same. What's the difference between them? I gotta pick one.....

 

[Grumpy]

http://garage.grumpysperformance.com/index.php?threads/adjusting-your-tps-and-iac.168/

http://garage.grumpysperformance.co...usting-your-tps-and-iac.168/page-2#post-90493

http://garage.grumpysperformance.co...8mm-throttle-body-on-your-tpi.290/#post-54181

http://garage.grumpysperformance.com/index.php?threads/my-current-corvettes-383-combo.430/


I also have a 1000cfm rated BBK throttle body on my corvette
if your iac (IDLE AIR CONTROL) valve whistles there's surely a vacuum leak,
or improperly sealed gasket
you most likely just need to take it off, inspect it, replace the gasket,
clean the IAC and throttle body and clean them carefully before re-install
read the thread and sub linked info above.

 

[Johnatthebox]

Ok thanks! If I were going to replace the iac valve is there a huge difference between the stock ones and the "high performance " ones? I can get a corvette one for 20$ but a BBK one is several times that....

 

[Johnatthebox]

I took it off took it apart ,sprayed it out, put it back on, and still the loud whistle. If I plug the iac hole on the thrittlebody with my finger. It shuts up and my idle drops about 150rpm down to where it probably should be.

 

[Johnatthebox]

But when its sucking air making the whistle is when I'm at 14.7( more like 14.5 really) ....and that's the target ratio. Right?

 

[Grumpy]

can you post a clear picture of the "HOLE" your plugging with your finger that results in the idle rpm dropping 150 rpm?
there should be a air cleaner to throttle body hose connecting the throttle body to to the maf sensor and the air cleaner housing and this muffles any whistle
btw its common for an idler fan belt coaster wheel or an alternator bearing or power steering pump bearing to whistle or make a good deal of noise on these older c4 vettes