Idle set.

I know it says in big block letters that idle and air mixture are factory set and cannot be adjusted.Can anyone tell me why not.There is an idle adjustment screw on my 92 topaz.Is this an environmental issue
or mechanical. Thanks
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 25 Sep 2003 20:50:58 GMT, darrell darcy

The idle speed is controlled by the ECM. The screw you see is to set the base idle which is not necessarily the idle speed that the ECM is going to want. If you set the idle speed too high, you may start getting fault codes and erattic engine performance. The only thing you can do in that area unless you know exactly what you are doing is to clean the throttle body which will usually correct any problems related to the physical adjustment of the throttle. Bottom line is to leave it as is unless you know both why you are making an adjustment and exactly how to do it.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The Idle speed and mixture are controlled by the processor. The "idle adjustment screw" you see on your Topaz is what is called the throttle hard stop. It's job is to prevent the butter fly valve from closing too far and binding in the throttle body at closed throttle. To a lesser degree it sets the lowest RPM for the engine in the event the air by pass valve closes completely.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.