As the title says. high idle speed on 99 SS ive changed the ICV and have replaced all tubing with pcv. Exept the port in the manifold( little plastic nipple in the rear). Any ideas to why i would have a high idle. Also it does not like to idle down when i pull it out of gear while goin down the road. Kinda scratchin my head on this one

 

I think I have read somewhere about a way to calibrate the Idle control sensor but I can't find it. Could you possibly still have a vac leak somewhere?

 

Only thing I can think of would be tb gasket or the vac port on the back of the manifold is cracked or loose sum how

 

Whats your idle speed at? Sounds like a vac leak to me

 

have it scanned fot trouble codes. could be a number of things.

 

ive scanned it for codes and it comes up with a high idle speed code once in awhile. the only other vac tubes or spots it could leak is the rear manifold nipple and the TB gasket. Ive changed every other vac tube. Also ive changed the PCV and the icv. It does sound like a vac leak to me. But i cannot find it for sum reason. It is starting to really **** me off LOL. It also could be a bad MAP sensor or bad MAF. Am i correct on this???? I still think its a vac leak sumwhere tho. It idles at about 1000 and when i pull it out of gear while goin down the road it stays at 1500 till i completly stop.

 

Did this happen out of the blue, or did you just recently work on something before this started happening?

 

There is a procedure for resetting the iac(idle air control)valve for a LT-1 but dont know if it works on LS-1.
.Depress accelerator slightly
.Start engine,then release accelerator pedal,run engine for 5 seconds
.Turn engine "OFF" for 10 seconds
.Restart engine and check for proper idle operation