PWM Idle Voltage Compensation
 

So, In my 2002 Miata running MSPNP-Pro I have an issue.

When I turn my headlights on I need an extra 2-3% duty on my IAC valve. Not a big deal, my closed loop pid reacts fast and gives it the extra duty it needs. The problem- Now all of my initial duty table values are 3% under what the car needs so as I let off the gas and come to a stop from moving the idle dips to 600 then closed loop pid raises the value again and it idles normal at 900 rpm.

From my understanding this is what the PWM Idle Votlage Compensation chart is for. However my voltage never moves no-matter what I do even though its obvious that the car looses voltage as I turn on the headlights. Thoughts?

From where I stand now I either have crappy idle with my headlights on or I raise my entire initial value chart by 3% and deal with the car not coming back to idle as smoothly as it could when the headlights are off, both are band-aids and worse than the oem ecu did it and that is not what I want.

Increase your PWM initial values to be able to compensate when your lights are on. Set them to whatever PWM value you need to keep a steady idle with the lights on, plus maybe an extra 1 or 2 percent. The car can still come back to idle, but it will first idle slightly higher then normal and PID will bring it down to your target. You can tune how long it takes for PID to reach your idle target. It should be somewhat smooth. Mine isn't OEM perfect, but don't really have problems with it.

That is what I was thinking as my second option in the original post but that is more of a band-aid, when I ran a piggyback on the same-setup with stock injectors the stock ecu handled it perfectly and I want my tune now to be just as good if not better than the stock ecu did it. I didn't spend big money on a real ecu to have worse idle characteristics. I'm sure there is something were both missing that is the real solution to this problem that doesn't involve having a good idle in one situation but an idle that stops at 1200 then to 900 every-time I come to a stop. Its these little things that really make a tune IMO.