wierd idle problem

Here's a good one to troubleshoot
1992 metro conv. lsi
has head reworked, ring job, all sensors checked and i think rigged correctly
heres the problem, bare with me
cold start up idle increases to 1500-2000
after warm up idle does not change , stays high
after turn off engine with a small wait maybe a min later restart eng. idle is low down to 300-400 which i know why that is because i tried to adjust for the high idle by turning in the idle adj. screw almost all the way closed. so why is this ?
my engine coolant temp is holding steady at 1/3 of the gauge,
i know the two temp sensors ,Engine coolant temp sensor, and engine air intake temp sensor are the primary inputs to the ecu for the idle control. i would like to add when i unplug one of the sensors the Idle control valve response correctly by increasing the idle thinking the engine is cold, plug the sensor back up ,the ecu then lowers the idle but never goes to 500 rpm until engine has shut down and i think the sensors get heat soaked which then the engines thinks its warmed and closes the idle control valve. i have purchased one new sensor which are the same or have the same ohm to temp values , i suspect the wire harness plugs and temp sensor got swaped some time in the past , so i a going to swap them the other way and see what happens,
i need ideas please help

Sp:
You have a quite clear idea about how to start troubleshoot. Do the swap and tell us what you find.

MC.
:cool:

well i found out the harnesses for each sensor where backwards so i swapped them back to there correct position i then took the time and hooked a spare temp sensor to the ECT harness and heated it up with a heat gun at that time the idle dropped to the idle adjustment screw setting i then readjusted the screw to 700 rpm as of right know the idle is at 1000 rpm i still need to reset the ECM and go for a long drive and see what the idle does.

question! when does the ECM go from Closed loop to Open loop? i feel the ecm never gets out of closed loop

technically "open loop" is when computer does not rely on any sensor info, "nd closed loop" is when it relies on info. so if it never gets out of open loop, it is never getting info that is crucial to making it run correctly. not sure what would cause this though.

ok so when a car is in open loop the car is warming up then when it reaches a certian temp the car then goes to closed loop. so what temp does the car goto closed loop?

i ran the car today for a total of two 40 min trips and the idle is still high around 2000 rpm after being parked for a min or two the idle goes down to 1700 rpm
i still think the car is not getting hot enough to lower the idle? maybe not
i need to know what is a good operation temp. for a metro some say 180 degrees i need to know what temp my sensor thinks it is and what it really is

does your electric radiator fan turn on? if so, coolant temperature sensor is fine. if not, or you aren't sure, disconnect the electrical connector to the ECT sensor (engine coolant temperature) and put a voltmeter to the connector (not sensor). turn ignition on but not motor and see if computer is giving if reference voltage. if yes, then check resistance between terminals of sensor itself. the warmer the engine is, the lower the resistance will be. if it doesn't change, ECT is probably bad. hope this helps.