General Fiat Uno 1.1ies Stalling Problems

[JCV]

:bang:

Can anyone technical help?

What gives the stepper motor unit the signal (4 pin plug)?

The problem that I am having is the car is cutting out when slowing down at trafiic lights etc, on a couple of occasions I have lifted the bonnet and noticed the stepper motor is not out and therefore the car will not tick over. Normally switching off the ignition and restartting clears this and the engine ticks over ok until next time.

Any help would be appreciated.

 

[andre79ge]

Hello! Stepper motor (idling control) is useful at cold start: ECU regulates the quantity of mixture opening the air intake a little bit more at cold than at hot engine. Then, during warming up, ECU slightly closes the air in order to give the correct idling rpm as soon as the engine ìs warmed up (I know my English is terrible... I don't know technical language...). Hwever...

You can check stepper motor in this way: you have to individuate stepper motor and push its leverage with a finger. At the same time you have to turn the acceleration control in order to accelerate the engine: keeping the control pushed you'll cause the ECU to think to be at idling (but you're artificially rotating acceleration command). So, ECU sees idling position to be incremented. If stepper motor and its system are properly working, you 'll see the stepper motor to arretrate its control, in order to take the accelerator position back. I'm not sure to be clear in my explanations...
However try to do it and try to see any movement.
You can also do another thing: try to start the car without push accelerator, only by inserting the first gear and slightly raising the clutch. Or you can keep the car stopped by handbrake and try to raise the clutch with a gear innested. Wait two or three seconds and then fastly push the clutch: if sepper idle control is working you'll listen to idling r.p.m. which is incremented respect to the normal condition. Then it'll return to its normal value in 1 or 2 seconds. Infact by raising the clutch you cause the r.p.m. to diminuish, and so ECU tries to increment it by opening accelerator via stepper motor.