On a gen3 ECM changing the cylinder volume (displacement) will automatically change the VE table(s)

 

On startup, my wideband reads 12 or so. After it idles for a minute, it starts leaning out and bounces between 14.7-15.7. I even see 16 sometimes. Why does it bounce so much?
How do I add fuel to the tune? Why can't I get the timing to smooth out? It bounces regardless of where I set it.

 

You're not going to get a rock solid 14.7 idle because of overlap contaminating the exhaust that's being read by the wideband. I asked Kyle (Goat Rope Garage) this question about "overlap contamination skewing the wideband reading at idle" on his live feed. He smile and said "yes most definitely".

Your spark has that saw tooth look because of the "overspeed" & "underspeed" settings in the "Idle Adaptive Spark Control" that 12- & 12+ is the correction when idle drops RPM or gains RPM. Those big numbers cause the see saw effect.

I've played with the overspeed underspeed settings at 12 -12 and it makes my truck sound off cam wise but it shook the truck side to side which I got tired of and set it back to a more sensible numbers.

Frost did my mail order base tune and here are the settings for the over & under. This will straighten out that saw tooth on the log

The 13 goes all the way to the left of the underspeed table <<<<<<<<<<<

 

Ok that’s fine. At idle, if the closed loop is active and there are no intake and exhaust leaks, the afr will be regulated by the O2 sensors. The same goes for driving as long as closed loop is active. The % of change needs to be in the data log so the trims can be applied to the ve table correctly. I’ll look over your data this morning. I’ll change the displacement tables if you like.

 

The log needs to be longer than that to really tell anything. here is the displacement change.

 

My wideband reads 12 in the beginning and then drops down to like 17 or 18 iirc. It bounces a bit but I never feel like it is a probably. You are just idling imo it can be lean but what do I know