How To Repair: How to Set the Idle Stop Screw on a Saturn

Saturday, October 15, 2011

Article provided by wikiHow, a wiki how-to manual.

If you are experiencing odd idling problems or your idle stop screw has been manipulated, you may want to try adjusting it.

This procedure assumes the IAC valve and throttle butterfly are free, clean and working properly.

Steps

1
Remove the air intake from the throttle body.
2
Start the car and wait until it is fully warmed up. This is usually indicated by the cooling fan coming on and going off.
3
Plug the IAC port in the throttle body. This is the small hole visible at the bottom of the inside of the throttle body.
4
Open the stop screw (CW) or close the stop screw (CCW) to adjust idle speed RPMs up or down respectively until you attain an idle between 450-650 RPMs.
5
Unplug the IAC port and allow the computer to reassess the proper settings.

Instead of plugging the IAC port, you may choose to unplug the IAC valve before turning on the car. The IAC valve should be completely closed after the car has been off for 10 seconds. If any air is leaking in the port after disconnecting a closed IAC valve, the computer may be unaware of the IAC valve's true position, or your throttle body and IAC valve may need cleaning.
If the correct RPM range is unattainable, there is another issue.
Try blocking off the IAC port slowly.
To open the stop screw (tighten) turn it clockwise.
To close the stop screw (loosen) turn it counter-clockwise.
If the screw is loose, you may wish to apply some locktite.
You may try turning the car off and disconnecting the battery for at least 30 seconds before attempting to run with an unblocked IAC port.
The car should be in neutral or park for manual or automatic transmission cars respectively.
A more precise method

As most instructions involving cars, this can be dangerous. Use caution!
Do not disconnect the IAC while the engine is running. This may cause the computer to lose track of the IAC's position.
Article provided by wikiHow, a wiki how-to manual. Please edit this article and find author credits at the original wikiHow article on How to Set the Idle Stop Screw on a Saturn. All content on wikiHow can be shared under a Creative Commons license.