Car idles very high, and now they won't smog me..

A new motor was put in my 91 Vr-4 a few years ago. Forged pistons and rods, new head, shaft eliminator kit.. ect.. The car has always idled very high. On start up when it is cold it will start at 3000 rpm and as it warms up it will drop to about 1750. I have never had a problem getting it smogged, but today when I went to smog it they told me they couldn't smog it because they needed the Idle at 1250 at the highest. This has never been a problem the past few years. Anyone have any suggestions for me.

Thanks a lot.

 

If it's that high with the biss screw in all the way you might have the ttl plate stop adjusted wrong, or you have just enough of a vac leak to let it run up.

start by checking the ttle plate stop screw adjustment & see if that will let you adjust your idle w/the biss screw. if that won't do it start looking for vacume leaks.

 

I'll check it, but this isn't a recent thing. I bought the block and rods from a guy who had the motor in his car with almost the same exact set up and his car did the exact same thing. So I figured it was normal, because of the shaft eliminator kit and what not.

 

My guess is that the throttle cable is mis-adjusted and holding the throttle open with you foot not on the gas.

 

throttle cable seems to be adjusted fine. Not sticking, a little slack and only opening when the gas is pressed.

 

Do you have a logger? Can you verify that the ECU is seeing the "idle-closed" switch connection?

 

I do not have a logger.

 

Depending how how much stuff I have running I can get my idle down to 1500 with the headlights on, and the heater running full blast, still need it lowered by 250 though lol.

 

Try this If your idle was off you're going to need to set you timing again also.

 

[Terry Posten]

Are you running the ISC/FIAV part on your TB or is it removed?

I would put money on the ISC being fully "turned" out allowing to much air into the intake at idle.

If you have the ISC, remove the 3 screws that hold the top part of the ISC on. The ISC coils will come off. Turn the ISC shaft (turn the black part of the shaft not the silver bearing) counter clockwise until it stops. You have now fully closed the ISC idle control path.

Here you have 2 options:

Option 1 - If you want to use your ISC again, turn the ISC shaft clockwise 1/2 turn and reinstall. The plug the ISC harness back in, set BISS at 3/4 turns out from fully seated, start the motor and adjust idle once fully warmed up to desired rpm speed.

Option 2 - If you do not want to use the ISC, leave ISC shaft fully seated (by turning counter-clockwise) and reinstall the ISC coils. DO NOT plug the ISC harness back in. Turn biss 1 turn out from fully seated and start the car.

ISC coil looks like this:

ISC base with shaft looks like this:

 

The Biss had rattled loose over the years it appears. Did the stuff that needed to be done and adjusted it. Now Idles at 1000 on the dot. Need to replace the plug, because it was missing.