I set the N-bias term to 255 on my latest bin. If I drive it around, stop, and put it in park it idles ~1200 rpm with an IAC of ~45. From what I understand the N-Bias is a post-kickdown, pre closed loop function.

Maybe there's something else I'm missing?

Another question: At $5D9 there's an IAC park/nuetral offset. I have all the hacks I can find but none of them say whether this value is added or subtracted in park/nuetral. Does this offset apply in open loop? Closed loop?

 

In park/neutral there isn't any closed loop idle control. There is a lower limit from the desired idle table and an upper limit from either $5E1 or $5E2 (I don't remember which). Also watch out for the term at $5F3. Below that temperature there isn't any upper idle RPM limit unless in gear.

The term at $5D9 is subtracted from the current steps while in park/neutral.

RBob.