you can test it.
Im pretty sure it is a simple analogue sensor so connecting a multimeter across the two terminals should indicate a resistance, now put the tip of the sensor in hot/boiling water and the resistance should change.
From the manual 60Deg C should have 70-90Ohms resistance. 100Deg C should have 21-24Ohms.
These are pretty cheap to replace anyway.
Coolent temp is a major factor in compensation for cold idle (warm up idle) most ECUs have a compensation table for coolent temp.
But ultimatly, as indicated a couple of years ago, if you remove all the other idle up gear, you won't get a good idle with this engine, you can increase the idle speed but it won't be as good as when all the gear is connected.

Bryan

!!UPDATE!!!
I bought the ute off of bugsie. It still had a cold start idle problem. I did the diagnostic mode on the ecu and code 13 came up which is engine temp sensor. What should I do replace it or can you test it?????!

i took the iac on the plenum off as i had spoken to a few people who said u don't need it with a standard ecu. i was told it was an idle up sensor for when the air con compressor comes on ans since no air con , no need for the sensor. I WAS TRYING TO TIDY THE ENGINE BAY UP A BIT. its not that it idles slow when cold its like it doesn;t get enough fuel..... just like a cold carby motor, and u have to puLL the choke out for it to run right when cold.. it has always done it and not changed since taking the sensor off so now i'm confused.....AND ONCE ITS WARM IT RUNS FINE :(:(:(:(:(:(:(:(:(:((:((:(:(:(:(:

PIGDOG,
The AAC (located under the throttle body) has a bimetal strip that controls a slide, the bimetal strip is heated slowly on startup, as it is heated the slide moves to close off bypass air, this occurs within approx 60sec of startup. There is no further feeback with the ECU with this item, essentially this is a dumb idle up on start item.

The Idle control valve (IAC i think it is called), the thing attached to the inside of the plenum is constantly controlled by the ECU via Pulse Width Modulation (PWM), this will change the open time of the valve to meet a set RPM target, the longer the valve is open the more air bypasses the throttle body = greater idle speed, this is the closed loop idle control.

If you have disconnected this item then you have no closed loop idle control. You can change the throttle stop screw to stop the butterfly from closing completely, thereby increasing your idle speed, but this is just masking your idle problem.

Bugsie,
As waz1200 has said, if you are running a air flow meter and have an air leak between it an the intake your ECU could calc injector pulse time for the amout of air. A faulty coolent sensor (there are two on the CA, one for the ECU and the other for the dashboard, they are located just behind the thermostat housing) could also trick the ECU into thinking the engine is colder/hotter then it actually is and this will also change the injector pulse time.

Thats my two cents worth anyway.

Bryan

So you have removed the TPS and coolant temp sensor? Why?

The sensor under the plenum is the knock sensor. In my experience this can be disconnected without any noticeable difference in performance. All that happens is that it reverts to the secondary map.

Might be time to spend some coin and get a professional to sort this out for you mate as it sounds like a bit of a mess.

I can recommend a couple of places in Brisbane. PM me if interested.

Matty

thanks for the help guys. the auto elec said he cleaned the injectors when he fixed it last time. it does blow some black smoke and smells a bit too tho. maybe one is faulty!!!! the 2 sensors on the side of the plenum are now removed but was doing it before i took them off recently. the sensor under the plenum is still there i haven't played with it at all. the other thing is the standard temp gauge in the silvia cluster doesn't work properley. it always reads about 1\3 once warm and doesn't go any higher..... which caused me to overheat it once so a new gauge with an inline temp sensor was installed and the old one stayed. maybe this is the problem. i will try your suggestions and see how my limited electrical knowledge serves me. do those sensors on the side of the plenum have to be there??????? i thought they could come off even with the standard ecu. how do i do a diagnostic check on the ecu. there is so much stuff not hooked up from standard it would probably give me a million faults..... i know red flash is worth 10 and a green is worth 1 but not sure how to do it

acc is your idle control valve im pretty sure (or its the iac), you will still need this if your running a standard ecu. in the manual it tells you how to adjust idle there's a little screw inside that valve and if the valve gets clogged with #OOPS# it will affect cold start and obviously idle speed, your sposed to clean it every so often. i would make sure your temp sensor is working properly and that there is no vacuum leaks, i wouldn't be touching the tps

i had this problem as i had neither the AAC of the one on the plenum connected, but what i want to know is what both of them do exactly

is the plenum one for just normal idle controlling, and the AAC for when its cold?

also have a look at ur idle up motor AAC Valve air bypass valve located under throttle body, usually a faulty coolant temp sensor will cause high idles, usually a vaccum leak will cause problems constantly rough idle, intercooler piping popped off will cause black smoke out the exhaust n stalling, n leakin injectors will cause smell out of exhaust of unburnt fuel and rough idle. they could be leakin over night foulin the plugs, take ur plugs out check them clean them start it n see if improves, blow through AAC valve see if opening. lots of things look around for the obvasious first

Also during cranking, CA18s batch fire the injectors for more fuel.
Bad idle is likely a leaky or stuck injector, unless you know the injectors are brand new.

Vaccuum leaks are also a killer for and MAFM equipped engine and their idle..

If you haven't moved the TPS.. I wouldn't necessarily start moving it now. Unless you follow the factory manual, to confirm that the 'off-idle' position is accurately set. This is the function for which the TPS is most important.