engine idle speed

[jerry50]

is there mechanical adjustment raise engine idle speed 2008 5.3

[MikeNH]

No. Engines haven't had mechanical idle control in probably 20+ years. All controlled by the computer.

[Doug_Scott]

I wouldn't say it cannot be adjusted mechanically. There is a throttle stop on the throttle plate. The adjustment is not just simply turn screw in to speed engine up, loosen screw to reduce idle speed. Changine the amout of air getting past throttle plates will change the idle speed, but, be aware that the computer will attempt reduce speed on its own. This would cause issues and will likely trigger the check engine light. Computer can only adjust the IAC motor(controlled vacuum leak) in order to contrill idld

 

Remember that when you adjust the throttle plate position, that changes the TPS sensor setting, which will spawn other events with the ECU.

 

"Drive by wire" engines will be harder to get the idle speed to stay changed.

 

If you are having idle speed issues, try cleaning IAC motor and passages in the throttle body,

[kstruckcountry]

Why would you want to raise idle speed? If it's idling below the regular speed, there's something wrong. If you want a higher idle than regular, there's really no good reason for that...