HP Tuners Tutorials

[Gregski]

Idle Tuning - Idle Spark Advance

And as Neal pointed out this behavior is perfectly normal the PCM is monitoring and making these adjustments, you will not see your idle RPM be a flat line at the desired number say 550, it will oscillate above and below it (within reason, more on this soon).

This brings us to the second item of the Holy Trinity: Timing. Let's open up the VCM Editor and see how the PCM uses Timing advance to keep the RPMs in line. We find the Idle Spark Advance under:

Engine \ Spark \ Advance tab \ Idle Spark Advance section