I had this problem a few times in the past. Sometimes my 1992 Buick Century will shut off for no apparent reason while idling. When I restart it, the engine will race for a few seconds before slowing down to normal idle speed. Could this be caused by a glitch in the car’s computer? Any ideas or answers will be appreciated.
It sounds like the Idle Air Control valve is hunting for the proper position while the engine is idling.
The IAC valve controls the engine idle speed under all conditions.
Does this only occur once the engine is warmed up?
Tester
+1 for Tester. Easy to clean or replace. Cheap to replace.
+2 for Tester. +1 for MY 2 CENTS.
It happens when the car is warmed up.
Then the IAC valve is being effected by the engine heat. And cleaning it won’t help.
As the windings in the IAC valve get hot it changes the resistance in the windings. And this will cause the IAC valve to hunt for the proper idle position.
Replace the IAC valve.
Tester