It is important to follow the following process to tune your PWM idle control:


  1. Tune the VE and ignition tables correctly.
  2. Disconnect/blank the idle valve and set the engine so it MECHANICALLY (via throttle stops/air bleed screws) idles at your desired idle speed (say 950rpm) when the engine is warm. Tune the VE Table so AFRs are correct. Do not aim for 14.7 at idle, usually slightly richer is better. If your engine wont idle mechanically set on the throttle stop, then idle control will be of no help at all!
  3. Reconnect your idle valve, and using idle settings, set your idle drive frequency and then set to idle mode to Manual Mode.
  4. Adjust the Manual idle duty (which takes effect even if outside of the idle conditions) up and down. Find the lowest number at which a difference happens (say 15%) and set that as your "PWM Min Duty". Then find the max manual duty that you hit your maximum required idle control speed, which might be 1400RPM, (and might be 55% for example) and set this as your PWM Max Duty.
  5. Set your Exit Idle Duty (under conditions) to the same number as PWM Min Duty. This means when the RPM/throttle etc are outside the idle zone, such as when driving, the idle valve returns to the "closed" state.
  6. Allow the engine to cool completely.
  7. Next set the idle mode to OPEN LOOP.
  8. Check your idle conditions are set correctly such that idle mode is normal when you run the engine. If it is out of range, adjust conditions, check throttle sensor etc.
  9. Now as the engine warms, adjust the Idle OL Duty table such that the engine idles how you want it. If you had a maximum of 55% and a minimum of 20% you may find that from very cold temperatures you start at 45% and taper down as temperature rises to the Min. PWM duty number. It is important to set the OL Duty Table correctly even for closed loop as it is used for startup and return to idle control.
  10. If you're happy to run Open Loop, then essentially you're done - enjoy - however if you wish to run closed loop which will automatically compensate for electrical load, oil pressure and so forth, then continue on below.
  11. For closed loop, we need to know the idle speeds you would like dependant on coolant temperature. Set these in the Idle target RPM table.
  12. Next, set the idle mode to Closed Loop, and tune the PID settings. The closed loop tuning example has more info on this.