Iac relearn

[el chevy]

if I’m able to close the Iac by jumping obd1 and it idles perfect after relearn process then when I turn it off and later turn it on right back to high idle it’s a 1987 chevy r10 5.0 automatic .do I need to drive it for it to change

 

[fast 99]

Do you have a scanner? What are the IAC counts at idle? Check vacuum leaks especially at the base plate. A high idle is most commonly caused by the computer not being able to control the speed. If the anti-tamper plug has been removed from the driver's side of the TBI body, suspect base idle needs to be set.