T Sport very high cold start idle

[Dan H842]

Firstly hello to everyone, I’m new to this site, have just bought a 2003 Yaris 1.5 T sport for my sons first car. 

Seems a great little car, yet I’m concerned about the idle during a cold start. Have read that they run at 2000 revs on start normally however ours is Reving at 2600 revs which sounds extremely high in the morning. Stays at 2600 for a few mins then it does slowly drop down to 750 eventually. 

Have cleaned the Maf sensor but no change.
Have put a basic code reader on ECU and no faults logged. 

Has anyone every had this issue or have any suggestions as to what could cause this. 

Cheers in advance Dan

[Madasafish]

There is an engine temperature sensor involved I think.. But the throttle body could be very dirty -...try cleaning that .

[Johan Damitha De Silva]

Our cars are getting on a bit. Pehaps I am clutching at straws here but I would certainly run some V-Power through it for the additives.  As the car is designed for low RON fuel they would have for years been running on fuel with only a little cleaning agent. Short trips would then hurt petrol engines (even worse in a diesel engine). This resolved issues with my faulty sensor and on cold mornings resolved issues with accessive white smoke. Its a shot in the dark with a small but significant chance of success. V-Power failed to resolve another car I had with a diesel engine so it is hit and miss.

[stantheman1]

Had this on a Corolla gti in the mid nineties, fault traced to a faulty temperature sensor.

 

Edit:

Seem to remember the technician telling me that the wax in the temperature sensor melts when the coolant warms up which in turn operates a switch to tell the ecu to reduce the revs to idle speed. Well it was something along those lines anyway!