Car idles very fast.i had it scanned but showed nothing wrong.

lots really,
scan it yet.
no year car told
no country told
answers will be hard, wrong or generic, all not good really.
what does WON"T IDLE mean
idles too fast hot or cold
idles too slow hot or cold.
stalls hot or cold.
does engine make full power hot and cold both?
??????? tell the good and bad or answers will be wrong or wild guessing./

this 17 years old a good run. nothing new here on failures this old.
all car fail that is what they all do eventually. (entropy etc)
let me guess never fails in others hands
and scans show nothing wrong, but sure too late then, they are gone.
so is and engine problem, so we focus there.
engines (gas, in order fail for 3 ways)

1. engine is bad, or cat melted (no) and egr stuck open (no)
2. bad spark (fuel can not burn lacking spark so why skip #2?)
3. bad fueling. too much or too little

in that order,

not enough evidence stated.
RPM's sink on start sometimes dies then usually it catches itself, idles high a few seconds then lines out.

runs great hot engine, so I guess fails only cold engine.
so bad spark plugs, bad spark coil boots or bad COPS
or bad CKP or CMP
why not just put in new plugs and new boots,
17years old those are NEVER GOOD.

ENGINE IS: 3.0L 2v or 4v (means 6x2 =12valvs or 6x4=24vavle heads.???? it has COPS, coil over plugs(spark)
6 cops ,6 new spark plugs and 6 new boots.
or learn now scan and drive,
or scan in the morning dead cold as the RPM go nuts
and does it misfire going nuts the RPM> misfire is spark first
or flooding 2nd the cold fast idle speed is wrong (IAC)

all I here is almost STALLS at cold start means why below 800 rpm hot and 1500 rpm cold so stalling is what MISFIRE?
can you prevent the too low RPM and stall with fast right foot action?
I say bad spark if not bad spark that is leaking injector or pair

learn to listen and feel for misfire,
and to use the right foot , adding throttle extra air to make it burn clean. Misfire s mostly violent. felt , heard, and see if you view the engine shack.
that is all I have but scanning it failing is how you fix cars

nobody can fix working car delivered a work car...
I have scan tool that logs and then play them back and bingo
GOTCHA. (P0306, and number 6 injectors is bad) see?

What engine does yours have ? 3.8 or 4.6 Do you have a professional type scanner that will show sensor data parameters ? Is the check engine light on ,or anyother light's ? Wrench symbol .
012 Idle Speed Problems Idle Speed Wrong I know yours only dies when put into gear , idles fine in park an neutral . Just showing what scan data is , if your not familiar with it. With the problem your having it's a necessity to have a scan tool that can view data pid's . You could spend a lot of buck's just replacing part's on recommendations from people on here . Testing an not guessing is the way to find the problem .

I think should be around 750.

Code for high idle is different,are you sure was 245?could be 225

good post. very good (what country or USA state?)
0F or 0C?? big difference, 0F is very very cold ,is that true?
this is international forum so do use the F or C so everyone knows.
so i bet the engine coolant temperature is out of control
on frigid days.
I use a scan tool see this engine, coolant do same its bad
The scan tool shows ECT it must rises to 180F (or more) and hold.
if not you have 2 problems, (either) the thermostat is bad, as below graphic shows. or you need to block off 1/2 the radiator with cardboard, ask any one in Canada that or Alaska.
it say thermostat is bad.
you might notice the cars heater is weaker, or if its weak all the time. not.

here is a classic bad Thermostat, slow and low.
it never reaches 180F ever.
and was insanely slow... 20miles to get this .......
the blue line is ECT (engine coolant temp sensor)
http://www.fixkick.com/my96-16v/TP-MAF-VSS-ECT-FUEL.JPG

this is just 1 step. if the coolant is at 180F or more
then you have IAC/ISC issues. if RPM is 1200 HOT, and hot is really HOT. then the ECU idle controls are INOP !
this can be 2 things, Bad ISC/IAC or fueling way wrong.
I have no idea at all what engine you have what size and cylinder count
or TOY name /num for engine???????
so can not guess which fuel system , so i stop here.

if EFI is map based, all air leaks to the plenum cause fast idle.
but i can only guess engine type.

the IAC is a thermal fast idle device, if coolant is warm, its closed.
that leaves the ISC< to control hot idle, either valve can fail.

May be a cooling sensor issue . If you can hook a scan tool to it and watch the coolant temp pid while idling high it may show a fluctuating reading .

A good Tech and a good scanner should be able to access the ' freeze frame ' thats shows a history of the components when the problem occours. This should give you a direction on which way to proceed, Guessing can very expensive fast.

You probably have a bad Idle Air Control Valve (IACV). In fuel injected carburetors when the throttle valve is closed the IACV opens and closes to control the idle speed. If it malfunctions the engine may rev up allowing the car if in gear to accelerate on its own . When I had a bad IACV in my Mitsubishi Lancer it would drive down the road at 50 mph with out touching the gas pedal. Fortunately, it could be slowed down by using the brakes (unlike the Toyota stories).

I would have a look at your coolant sensor, if it's reading the wrong temperature, it will cause a idle problem. If you can, get a scanner on it to verify it's operation.