right, i changed my temp sensor to try sort my idle but its only made a difference when its cold, now it idles at 1200 cold but its going crazy when warm, 2000 2500 rpm? anyone shed any light on this?

 

The fact that it made any difference shows you something was faulty.
Just wait till it gets fully warmed up, disconnect the ISCV, then will all electrical loads of apart from the engine running adjust to around 900 rpm, reconnect the ISCV, it will probably raise a little bit to start with, then settle to the base idle you just set to 900rpm.
The engine can only attain such speed that is has air for, so has to be getting in somewhere, most likely scenario is that it had a dodgy cts previously so people been fiddling about with base idle screw, on underside of the throttle housing to bodge it, but of course in the process not rectifying the actual problem.
tabetha

 

ok so is it the screw below the throttle housing thats the big one with a lock nut on it? what would happen if the car was run with the ISCV unplugged?

 

It is a fairly common problem with the cosworths. What might also help if cleaning out the ISCV as they can get crap in them. It might actually be the ISCV causing your problems. Turn the car on and unplug it and you will probably notice the revs drop to what they should be. However it does serve a purpose and not running it might cause other idle problems.

I have had a couple of problems with idling but they seemed to be short lived. It is certainly something to do with the throttle body and or it's surrounding parts.

 

yea the car seems to idle perfect with it unplugged. tried cleaning it out also but it has not made a blind bit of difference

 

The fact that it idles perfect without ISCV plugged in, shows you the base idle is correct.
The FACT that the revs are raised to 2500 rpm shows you the iscv is WORKING.
The iscv is there to ONLY RAISE the revs, it cannot lower the revs.
Now you need to find out WHY the iscv is being told to do what it is doing.
My best guess would be the CTS, but you would have some seriously rich running problems if it was, so I would get CO looked at next, then if no joy, check all sensor values.
tabetha

 

co2 was looked at today and is perfect... sensor values?

 

has anyone been at the throttle position sensor,incorrect throttle position sensor setting can give very high idle when warm, as i found out many moons ago thanks to a very knowledgable person on here
can remember the values for the 2wd, its either 5 ish volts at idle or zero volts at idle as its the opposite for the 4x4, but might be worth checking

 

they could wll have been, i've not had the car long and was off the road for 6 years so findin a few running in issues, can the tps be adjusted atall? are they all usually red?

 

Most 2wd tps are red, yes they can be adjusted, as they have elongated holes where they fix to the throttle housing.
At idle you should see around 4.6 volts, and at full throttle around 0.6, or it could be the other way around, as I've forgotten!!
Is the car modded at all ?
Although the co is perfect, I would look at CTS try unplugging it and see if any joy.
tabetha

 

4.4 Closed, 0.35 wide open on a PF01. They come in red and black, so do PF09s.

If you have a hugely high idle when it's warm, it could be a knackered TPS telling the ECU to dump fuel in, or a split gasket or hose on the inlet after the throttle body. My inlet manifold gasket split and had an idle that crept up as it warmed up - right up to 2500.

Image from bigturbo.co.uk:

 

as a ballpark adjust the sensor to the middle of the slots on the sensor housing where the two screws secure it to the throttle housing,to see if it makes any difference, but you will need a volt meter to ensure it is correct in the end

 

Its a brand new CTS i have just fitted in the last few days.....


cozmeister

its doing exactly what your describing, creeping up the warmer the car gets... i'll check the inlet gasket tomorrow

 

It will creep up the warmer it gets, like I said to start with it needs air to maintain rpm, either something is telling the iscv to be open that much, or the CTS was faulty, the cts appears from the co not to be faulty.
I would have though a boost leak might have been heard if this bad, saying that it only takes a minute amount of air to do 2500 rpm with no load.
Just spray eezi start around the joints, cleans your engine nicely as well!!
I'm surprised a dud TPS would make that much difference, but I don't use the weber mareli anymore.
These things annoy me, it's just so much easier with the "patient" in front of you, fancy a drive to Norfolk!!
tabetha

 

Tabetha...

Ah i understand what your saying now.. i'll give that a try this weekend, got some free time sunday so gunna double check hoses etc all again,
if it would mean it would end up fixed i mite've just done that!

 

Well I've been to Shetland, and Orkney islands, and it's too cold for me!!
tabetha

 

it certaily is that indeed! been blowing a gale force 8/9 for the last 3 days! that and lashing it down rain....

if you dont mind me asking what brought you up to here?

 

An aeroplane? That's a long way to go just to get away from Norfolk for a while, tabs.