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ISCV is located under the number four throttle body and behind the plenum (Correct spelling just for JP's benefit ) chamber, bolted to the block from memory. See pic below.
The ISCV is adjustable but it's hard to adjust as you need to remove it to adjust it which is a PITA as you need to remove the whole plenum chamber and all the other crap in the way. It has two screws which locate the base. The screws run in an arced slot and loosening the screws and turning the base will adjust the base spring pressure which in turns sets the minimum valve opening and therefore the minimum idle. Since the idle control is closed loop the ECU can still override this and adjust the idle upwards a fair bit and even downwards slightly against the spring pressure.
Typically the problem with the 20V's idle (at least here in Australia) is that as a result salt residue / corrosion from the shipment of front cuts from Japan they tend to sieze up pretty easily (seen at least 6 siezed). Most people don't know this is a problem so they hook the engine up and drive it without any preventative maintainence beforehand.
The valve is operated by a simple electro-magnetic coil which is controlled by the ECU amplifying the signal to either side of the coil to either increase or decrease the idle as required. When the valve is siezed the ECU keeps amplifying the signal more and more to change the idle but as long as it's working against a siezed or stiff valve it will eventually burn out the amplifier / transistor which controls the idle. This is, more often than not, the cause of 20V low idle problems.
The ISCV is adjustable but it's hard to adjust as you need to remove it to adjust it which is a PITA as you need to remove the whole plenum chamber and all the other crap in the way. It has two screws which locate the base. The screws run in an arced slot and loosening the screws and turning the base will adjust the base spring pressure which in turns sets the minimum valve opening and therefore the minimum idle. Since the idle control is closed loop the ECU can still override this and adjust the idle upwards a fair bit and even downwards slightly against the spring pressure.
Typically the problem with the 20V's idle (at least here in Australia) is that as a result salt residue / corrosion from the shipment of front cuts from Japan they tend to sieze up pretty easily (seen at least 6 siezed). Most people don't know this is a problem so they hook the engine up and drive it without any preventative maintainence beforehand.
The valve is operated by a simple electro-magnetic coil which is controlled by the ECU amplifying the signal to either side of the coil to either increase or decrease the idle as required. When the valve is siezed the ECU keeps amplifying the signal more and more to change the idle but as long as it's working against a siezed or stiff valve it will eventually burn out the amplifier / transistor which controls the idle. This is, more often than not, the cause of 20V low idle problems.
Also consider:
Gummed up Throttle bodies. Some Carb and TB cleaner shot through there will help that.
Check adjustment of the TPS (I need to insert some kind of link here.)
Loose, Broken, Cracked, Incorrect Vac lines and A/C idle up.
And secondly here are some pics: http://4age20v.blogs.../2008/03/21/44/
