Idle control valve

[George M. Dailey]

At 10:38 AM 10/24/96 -0600, you wrote:
> 
>
>Greetings All.
>
>I have a question concerning the idle system used in EFI. How fast and what
>factors are involved in the closing of the idle control valve once the 
>throttle plates have opened ?
>
>Thanks in advance
>Joe
>
>
>Joseph D. West
>Electronics Lab. Supervisor
>College of Mechanical Eng.
>Ohio State University
>
>(614) 292-2845
>Fax (614) 292-3163
>
It has been my observation that the stepper motor used in GM systems goes
full open to full closed in about 2-4 seconds. I think when the speed is
above 25mph the ecm either closes or opens the IAC valve. Probably to keep
the stepper motor and associated parts from locking in place. I know for a
fact that at some point the ecm will comand the IAC to shut and ecm will
count the steps from the reference to establish the correct idle position. I
guess it's forgetful, (second thing to go with age).

GMD

GMD