I have a 2006 M6 GTO that's mechanically completely stock. With HP Tuners I have it tuned to run E-85. The problem that I'm encountering is that no matter how I set the Idle>Idle Airflow>Airflow Final Minimum or Idle>Idle RPM>Target Idle Speed I cannot get the car to drop under 800 RPM. I did a scan post flashing the tune with the lower Airflow Final Minimum and Target Idle Speed and the Idle Desired RPM is still 800. However, if I use the VCM controls to set the idle speed the Idle Desired RPM will move and it will idle as low as 650.
I'd really like to be able to slow the idle down on my car. 800 at idle seems a little high and it uses 1 gal/hr on E-85. Most of the time when I scan I drop it down to 650 and have never had a problem with driveability.