With TR 4 cylinder
When starting the engine on a cold start is the ISC closed and the fast idle valve works by it's self, and then when the engine is warm the ISC is released to star working??????????

Or is it that there is just extra air flowing through the fast idle valve and when it is open and as the engine warms up the fast idle valve slowly closes and slows the idle, and the ISC is open the whole time?????????????
Thanks to all that reply

second option is correct

Yeps. The ISC is an electronic stepper, controlled by the ecu.. whereas the fast idle valve is governed by coolant temperature.

I have two throttle bodies. I was thinking of doing some experimenting.
I have been sick of when starting the car when cold and it idles at 2000rpm for about 4mins or so. Putting the car in gear at 2000rpm is not good for the trans or the engine mounts. If your running late for what ever reason some times you might end up putting it in gear at high revs say 1500. I normally turn on the air and wait for a bit, but really I think the fast idle valve in these things is over the top.
I have been a qualified welder for more years than I can remember, and was thinking of either half welding it up or fully.
The car idles at 1000rpm in park anyway when warm, so as to achieve a 750 idle in gear.
It would be nice to start the car when cold and it only idled at say 1100-1200rpm.

This car is my daughters first car and she only has her L's and a couple of times she has just wacked it in gear at 2000 rpm reverse BANG!!
My nice new shiny mounts are taking a beating****

One other guy at work has a real ruffy TR magna and it idles on about 2500 when he starts it and he just slams it into gear. His mounts are that shot, when it idles in gear you have to wear your seat belt or you'll get thrown out the car.

2000rpm sounds way too high! My TS never ran above 1500rpm on the coldest of mornings, and dropped down to 1200ish after 20 secs or so. Definitely make sure the throttle stop screw hasn't been tampered with. Alot of mechanics who have little knowledge on the subject like to use the throttle stop to adjust idle speed. This messes with the tps, and also means that the idle air screw has to be wound in very far to compensate. The workshop manual describes how to re-set the throttle stop IIRC. Also remove the throttle body heater hoses and make sure there's no blockage inside the TB.

2000rpm sounds way too high! My TS never ran above 1500rpm on the coldest of mornings, and dropped down to 1200ish after 20 secs or so. Definitely make sure the throttle stop screw hasn't been tampered with. Alot of mechanics who have little knowledge on the subject like to use the throttle stop to adjust idle speed. This messes with the tps, and also means that the idle air screw has to be wound in very far to compensate. The workshop manual describes how to re-set the throttle stop IIRC. Also remove the throttle body heater hoses and make sure there's no blockage inside the TB.

* Yes you have a good point* the throttle body that is currently on the car is worn.
Not long ago I had Mitsubishi set the base idle to 850rpm in Park, just to see how it would run. To achieve this setting they had to have the idle screw turned all the way in.
I asked about the throttle stop. They said the throttle stop was correctly set. They told me that the throttle body it's self was just worn.

I have a newer throttle body in my shed when you hold this up to the sun no light shines past the butterfly. (Unlike the old one, not much, but still )

The old one that is one the car now I have pulled the whole thing apart and cleaned it.
The water channels that carry coolant to the fast idle valve are perfectly clear.

Thanks again for every ones replies. Some times it's a bit like a jigsaw puzzle and all the bits of info help you get a better under standing of what;s going wrong.