I've been trying to tune out a rough idle and low speed cruise. After reading all of the proportional gain threads I could find, I decided try changing the PRP tables to see how that affected the o2 voltage. I ended up setting all of the prp tables to zero and was surprised to see the pattern still looked normal. What am I missing?

It does still look normal, are you sure you flashed it in and are running that BIN?

What occurs when there is no proportional gain is that the ECM ends up using the INT to create cross-counts. So the O2 still swings, just not as fast as when the proportional gains are being used.

RBob.

That does sound like something I would do. But I just plugged in and read the active BIN . All of the PRP parameters are zero.

Check the data log to see what the INT is doing. Without prop gains it should be rising and falling to create x-counts.

RBob.

INT and BLM are not moving much. It is running good and wide band stays about 14.7. I'm trying to understand how it can oscillate rich/lean without prop gains or the INT moving.

My guess is that the AFR is so close to 14.7 that the O2 sensor is flicking back and forth between rich & lean. The screen shot shows that the injector PW is barely moving.

RBob.