MSefi.com read only forum (Jan.15,2018)

the higher my control authority gets the worse my engine rpm chases back and forth a few hundred rpm under cruise or any load. even idle. why is this? i moved it down to 3% so it wouldnt do it anymore.

Too much controller authority will do just that - it overcorrects and oscillates back and forth. The closer to correctly tuned the VE table, the less oscillation you get, but you still don't want more than 10% authority or so.

Basically, your O2 sensor is getting a reading that is way out of whack with the desired target in the particular AFR table entry or entries you are operating in. The ECU tries to adjust the pulsewidth to bring the actual reading closer to the desired target. The amount that the ECU will adjust based on the O2 reading is the percentage selected in the controller authority setting. So, if the actual reading is 20% richer or leaner than the target, but the controller authority is set to 5%, the maximum the pw will be changed will be only enough to result in a 5% correction toward that goal. As you can imagine, a target AFR and an O2 reading that are very different, combined with a high controller authority percentage can result in quick and dramatic changes that are not always desireable. As Matt pointed out, the closer the target AFR is to the corresponding VE table entry (which results in the actual AFR and therefore, the O2 reading) the less rapid variation that takes place. This is great way to tune. By watching the O2 correction percentage at different loads/speeds you will see how close the two key tables are. When there is little correction, and the engine is running well, you are there.
Paul

could it also just be a side effect of my big behind cam (236/248 duration) 113lsa 600+lift?