Technical Idling problems when cold

[familyfarrugia001]

I've got a Cinquecento Sporting whose engine is not idling properly when cold and the engine dies away. In order to get the car running, I've got to keep the engine revving until the engine warms up. When it warms up slightly, it idles at around 500rpm with difficulty. Once it is properly warmed up, it revs at 900rpm with no problem whatsoever. Even starting from warm is no problem at all. I've checked all the usual stuff ie vacuum pipes and cables, connectors etc and all seems fine. Any ideas pls?
jf

 

[Pep0]

borrow a multi meter set it to resistance...
remove the plug on the coolant temperature sensor and measure resistance cold
it needs to be near to nominal value which value lurks on site somewhere...

 

[fingers99]

Sounds likely.

The coolant temp sensor is the blue coded one, near t5he throttle body.

 

[familyfarrugia001]

Thanks for your help guys. Will keep you posted on outcome.

 

[familyfarrugia001]

Hi guys. It appears that it's not the temp sensor that is causing the problem. I checked the sensor's resistance at various temperatures as you suggested and the resistances that i got match pretty well with the values that I found on one of the threads of this forum. I'm suspecting that the culprit could be the idling stepper motor. It appears that a supply is coming on it but i'm not sure whether it is functioning properly. I intend taking it out of its housing and check for proper operation. What do you think please?
F

 

[fingers99]

Checking and cleaning costs nothing. Worth a shot.

After that, my next move would be a dry and wet compression test.

 

[Pep0]

I'd do the compression tests first and check the oil cap for 'mayo'.

 

[rallycinq]

All the sensors are earth switched, it makes it easier to control.

De-coking the solenoid will do it no harm and might cure the problem.

Cheers

D