Fuel trim at idle.

[Andrew Bagwell]

Using my SCT X4 to monitor a few things I'm noticing that my fuel trims at idle are lean. While driving around they hover right around "1.00" +/- .03. However when I come to a complete stop they nosedive to "0.80" , then go back up once I start driving. 1999 Explorer 4.0 SOHC, Car is running great. Is this normal? Thanks in advance.

 

[Blown]

If it is not stumbling off idle I wouldn't worry about it.

It's probably getting a bit more air through that throttle body and IAC combo at idle. You could richen the very bottom of the MAF curve to make it go away.

 

[Andrew Bagwell]

Thanks for the reply! I had a custom tune done and it helped a lot.... still in the low 90s at idle but I'm not getting a CEL and the car runs fine. Thanks again!